A 4-month-old girl is brought to the physician by her father because he is concerned that she appears sickly and lethargic. She has always had a pale complexion, but it has been getting worse over the past month. She was delivered at home at 36 weeks to a 26-year-old woman following an uncomplicated pregnancy. She has not yet been examined by a physician. She is in the 2nd percentile for head circumference, 10th percentile for length, and 8th percentile for weight. Physical exam shows a pale infant with facial features of micrognathia, flat nasal bridge, and microopthalmos. The eyes are set widely apart and strabismus is present. She has a high arched palate and there is fusion of the cervical vertebrae with flaring of the skin around the neck. A 4/6 holosystolic murmur is heard best on the left chest. Laboratory studies show:
Hemoglobin 6.6 g/dL
Hematocrit 20%
Leukocytes 5400/mm3
Platelets 183,000/mm3
Mean corpuscular hemoglobin 41.3 pg/cell
Mean corpuscular hemoglobin concentration 33% Hb/cell
Mean corpuscular volume 125 μm3
This patient is most likely to have which of the following findings?
Q42
A 1-month-old boy is brought by his parents to an orthopaedic surgeon for evaluation of bilateral club feet. He was born at term to a G1P1 mother but had respiratory distress at birth. Furthermore, he was found to have clubfeet as well as other extremity contractures. Physical exam reveals limited range of motion in his arms and legs bilaterally as well as severe clubfeet. Furthermore, his face is also found to have widely separated eyes with epicanthal folds, a broad nasal bridge, low set ears, and a receding chin. Which of the following conditions was most likely seen with this patient in utero?
Q43
A 1-month-old male newborn is brought to the physician because of poor feeding, a hoarse cry, and lethargy for 1 week. The boy was born in Mozambique, from where he and his parents emigrated 2 weeks ago. He is at the 95th percentile for head circumference, 50th percentile for length, and 70th percentile for weight. Physical examination shows scleral icterus, an enlarged tongue, and generalized hypotonia. The abdomen is distended and there is a reducible, soft protruding mass at the umbilicus. Which of the following is the most likely cause of these findings?
Q44
A 6-week-old girl is brought to a pediatrician due to feeding difficulty for the last 4 days. Her mother mentions that the infant breathes rapidly and sweats profusely while nursing. She has been drinking very little breast milk and stops feeding as if she is tired, only to start sucking again after a few minutes. There is no history of cough, sneezing, nasal congestion, or fever. She was born at full term and her birth weight was 3.2 kg (7.0 lb). Her temperature is 37.0°C (98.6°F), pulse rate is 190/min, and respiratory rate is 64/min. On chest auscultation, bilateral wheezing is present. A precordial murmur starts immediately after the onset of the first heart sound (S1), reaching its maximal intensity at the end of systole, and waning during late diastole. The murmur is best heard over the second left intercostal space and radiates to the left clavicle. The first heart sound (S1) is normal, while the second heart sound (S2) is obscured by the murmur. Which of the following is the most likely diagnosis?
Q45
A 26-year-old woman with poor prenatal care and minimal antenatal screening presents to the emergency department in labor. Shortly thereafter, she delivers a baby girl who subsequently demonstrates symptoms of chorioretinitis on examination. A series of postpartum screening questions is significant only for the presence of multiple cats in the mother’s household. The clinical team orders an enhanced MRI examination of the infant’s brain which reveals hydrocephalus, multiple punctate intracranial calcifications, and 2 sub-cortical ring-enhancing lesions. Which is the most likely diagnosis?
Q46
A 2-year-old boy is brought to a pediatrician because his parents have noticed that he seems to be getting tired very easily at home. Specifically, they have noticed that he is often panting for breath after walking around the house for a few minutes and that he needs to take naps fairly often throughout the day. He has otherwise been well, and his parents do not recall any recent infections. He was born at home, and his mom did not receive any prenatal care prior to birth. Physical exam reveals a high-pitched, harsh, holosystolic murmur that is best heard at the lower left sternal border. No cyanosis is observed. Which of the following oxygen tension profiles would most likely be seen in this patient? (LV = left ventricle, RV = right ventricle, and SC = systemic circulation).
Q47
A child is born by routine delivery and quickly develops respiratory distress. He is noted to have epicanthal folds, low-set ears that are pressed against his head, widely set eyes, a broad, flat nose, clubbed feet, and a receding chin. The mother had one prenatal visit, at which time the routine ultrasound revealed an amniotic fluid index of 3 cm. What is the most likely underlying cause of this patient's condition?
Q48
A 3-day-old female newborn delivered vaginally at 36 weeks to a 27-year-old woman has generalized convulsions lasting 3 minutes. Prior to the event, she was lethargic and had difficulty feeding. The infant has two healthy older siblings and the mother's immunizations are up-to-date. The infant appears icteric. The infant's weight and length are at the 5th percentile, and her head circumference is at the 99th percentile for gestational age. There are several purpura of the skin. Ocular examination shows posterior uveitis. Cranial ultrasonography shows ventricular dilatation, as well as hyperechoic foci within the cortex, basal ganglia, and periventricular region. Which of the following is the most likely diagnosis?
Q49
A 9-year-old boy is brought to the physician because his parents are concerned that he has been unable to keep up with his classmates at school. He is at the 4th percentile for height and at the 15th percentile for weight. Physical examination shows dysmorphic facial features. Psychologic testing shows impaired intellectual and adaptive functions. Genetic analysis shows a deletion of the long arm of chromosome 7. Which of the following is the most likely additional finding in this patient?
Q50
A 4-year-old boy is brought to the physician by his parents for a well-child examination. He has been healthy and has met all development milestones. His immunizations are up-to-date. He is at the 97th percentile for height and 50th percentile for weight. His vital signs are within normal limits. The lungs are clear to auscultation. Auscultation of the heart shows a high-frequency, midsystolic click that is best heard at the fifth left intercostal space. Oral examination shows a high-arched palate. He has abnormally long, slender fingers and toes. The patient is asked to clasp the wrist of the opposite hand and the little finger and thumb overlap. Slit lamp examination shows superotemporal lens subluxation bilaterally. Which of the following is the most appropriate next step in management?
Congenital defects US Medical PG Practice Questions and MCQs
Question 41: A 4-month-old girl is brought to the physician by her father because he is concerned that she appears sickly and lethargic. She has always had a pale complexion, but it has been getting worse over the past month. She was delivered at home at 36 weeks to a 26-year-old woman following an uncomplicated pregnancy. She has not yet been examined by a physician. She is in the 2nd percentile for head circumference, 10th percentile for length, and 8th percentile for weight. Physical exam shows a pale infant with facial features of micrognathia, flat nasal bridge, and microopthalmos. The eyes are set widely apart and strabismus is present. She has a high arched palate and there is fusion of the cervical vertebrae with flaring of the skin around the neck. A 4/6 holosystolic murmur is heard best on the left chest. Laboratory studies show:
Hemoglobin 6.6 g/dL
Hematocrit 20%
Leukocytes 5400/mm3
Platelets 183,000/mm3
Mean corpuscular hemoglobin 41.3 pg/cell
Mean corpuscular hemoglobin concentration 33% Hb/cell
Mean corpuscular volume 125 μm3
This patient is most likely to have which of the following findings?
A. Triphalangeal thumb (Correct Answer)
B. Exocrine pancreatic dysfunction
C. Mild neutropenia
D. Target cells
E. Spherocytes
Explanation: ***Triphalangeal thumb***
- This patient's presentation with **macrocytic anemia**, **growth retardation**, **cervical vertebral fusion** (Klippel-Feil anomaly), and distinctive **facial features** (micrognathia, flat nasal bridge, microophthalmos, widely set eyes, strabismus) is highly suggestive of **Diamond-Blackfan anemia (DBA)**.
- **Triphalangeal thumb** or other **thumb/radial abnormalities** are present in 30-50% of DBA patients and are a characteristic feature of this condition.
*Exocrine pancreatic dysfunction*
- **Exocrine pancreatic dysfunction** is characteristic of **Shwachman-Diamond syndrome**, which also presents with bone marrow failure but typically involves **neutropenia** and skeletal abnormalities different from those seen here.
- While both can cause anemia, the specific constellation of features in the patient (macrocytic anemia, craniofacial dysmorphisms, Klippel-Feil) points away from Shwachman-Diamond syndrome.
*Mild neutropenia*
- Although **neutropenia** can be seen in some bone marrow failure syndromes, **Diamond-Blackfan anemia** is primarily characterized by isolated **red cell aplasia**, leading to severe anemia with normal leukocyte and platelet counts initially.
- The patient's **leukocyte count of 5400/mm3** is within the normal range for an infant, indicating no neutropenia.
*Target cells*
- **Target cells** are typically associated with **thalassemias**, **hemoglobinopathies**, or **liver disease**, which cause microcytic or normocytic anemia.
- This patient has **macrocytic anemia** (MCV 125 μm3), making target cells an unlikely finding.
*Spherocytes*
- **Spherocytes** are characteristic of **hereditary spherocytosis** or **autoimmune hemolytic anemia**, conditions that cause hemolytic anemia.
- While these can cause anemia, they do not typically present with the specific congenital anomalies and macrocytic picture seen in this patient.
Question 42: A 1-month-old boy is brought by his parents to an orthopaedic surgeon for evaluation of bilateral club feet. He was born at term to a G1P1 mother but had respiratory distress at birth. Furthermore, he was found to have clubfeet as well as other extremity contractures. Physical exam reveals limited range of motion in his arms and legs bilaterally as well as severe clubfeet. Furthermore, his face is also found to have widely separated eyes with epicanthal folds, a broad nasal bridge, low set ears, and a receding chin. Which of the following conditions was most likely seen with this patient in utero?
A. Oligohydramnios (Correct Answer)
B. Polyhydramnios
C. Maternal hypertension
D. Intrauterine infection
E. Chromosomal abnormality
Explanation: ***Oligohydramnios***
- This patient presents with the classic features of **oligohydramnios sequence (Potter sequence)**, which results from prolonged oligohydramnios in utero causing fetal compression.
- **Key features present**: bilateral club feet, multiple extremity contractures (arthrogryposis), respiratory distress at birth (from **pulmonary hypoplasia**), and characteristic **Potter facies** (widely separated eyes, epicanthal folds, broad nasal bridge, low-set ears, receding chin).
- The **respiratory distress** is particularly significant, as oligohydramnios prevents normal lung development, leading to pulmonary hypoplasia—a life-threatening complication at birth.
- The **facial features and limb contractures** are direct consequences of mechanical compression from insufficient amniotic fluid, not intrinsic developmental defects.
*Chromosomal abnormality*
- While chromosomal abnormalities can cause multiple congenital anomalies, the **specific constellation of findings** in this case—particularly the **Potter facies, pulmonary hypoplasia with respiratory distress, and compression-related deformities**—is pathognomonic for oligohydramnios sequence.
- Chromosomal abnormalities typically present with a different pattern of malformations depending on the specific syndrome and would not specifically cause the compression-related findings seen here.
*Polyhydramnios*
- **Polyhydramnios** (excessive amniotic fluid) is associated with conditions preventing fetal swallowing (esophageal/duodenal atresia) or increased urine production (twin-twin transfusion syndrome, fetal anemia).
- It causes **increased space** for fetal movement, which would prevent rather than cause contractures and deformities.
- Polyhydramnios does not cause the compression-related features seen in this patient.
*Maternal hypertension*
- **Maternal hypertension** can lead to **intrauterine growth restriction (IUGR)**, placental insufficiency, and preterm birth.
- However, it does not directly cause oligohydramnios severe enough to produce Potter sequence, nor does it cause the specific facial and limb deformities described.
*Intrauterine infection*
- **Intrauterine infections** (TORCH infections) can cause microcephaly, intracranial calcifications, chorioretinitis, hepatosplenomegaly, and hearing loss.
- They do not typically cause the **mechanical compression deformities** (club feet, contractures, Potter facies) or **pulmonary hypoplasia** characteristic of oligohydramnios sequence.
Question 43: A 1-month-old male newborn is brought to the physician because of poor feeding, a hoarse cry, and lethargy for 1 week. The boy was born in Mozambique, from where he and his parents emigrated 2 weeks ago. He is at the 95th percentile for head circumference, 50th percentile for length, and 70th percentile for weight. Physical examination shows scleral icterus, an enlarged tongue, and generalized hypotonia. The abdomen is distended and there is a reducible, soft protruding mass at the umbilicus. Which of the following is the most likely cause of these findings?
A. Congenital toxoplasmosis
B. Beckwith-Wiedemann syndrome
C. Acid maltase deficiency
D. Thyroid dysgenesis (Correct Answer)
E. Biliary atresia
Explanation: ***Thyroid dysgenesis***
- The constellation of **poor feeding**, **hoarse cry**, **lethargy**, **scleral icterus**, **enlarged tongue (macroglossia)**, **hypotonia**, **distended abdomen**, and an **umbilical hernia** (reducible, soft protruding mass) is highly suggestive of **congenital hypothyroidism**, most commonly caused by **thyroid dysgenesis** (absent or ectopic thyroid gland).
- The large head circumference reflects **delayed bone maturation** and **persistent open fontanelles**, common in untreated congenital hypothyroidism.
- The patient was born in Mozambique, where newborn screening may not be universally available, leading to delayed diagnosis.
*Congenital toxoplasmosis*
- This typically presents with the classic triad of **chorioretinitis**, **hydrocephalus**, and **intracranial calcifications**.
- While it can cause **scleral icterus** (due to liver involvement), the other prominent features like hoarse cry, enlarged tongue, hypotonia, and umbilical hernia are not characteristic.
*Beckwith-Wiedemann syndrome*
- Key features include **macrosomia** (large body size), **macroglossia** (large tongue), **omphalocele** or **umbilical hernia**, and **visceromegaly**.
- Although this patient has macroglossia and umbilical hernia, the absence of macrosomia (70th percentile for weight is normal) and the presence of **lethargy**, **hoarse cry**, **prolonged jaundice**, and **hypotonia** point away from this genetic overgrowth disorder.
*Acid maltase deficiency*
- This lysosomal storage disorder (also known as **Pompe disease**) involves glycogen accumulation and primarily causes severe **cardiomyopathy**, **muscle weakness**, and **hypotonia**.
- It does not typically present with hoarse cry, enlarged tongue, prolonged jaundice, or umbilical hernia.
*Biliary atresia*
- The primary symptom is **persistent jaundice** (scleral icterus) due to impaired bile flow, typically appearing after 2-3 weeks of life, along with **acholic (pale) stools** and **dark urine**.
- While it explains the icterus, it does not account for the other pervasive symptoms of **hoarse cry**, **lethargy**, **enlarged tongue**, **hypotonia**, and **umbilical hernia**, which are hallmarks of congenital hypothyroidism.
Question 44: A 6-week-old girl is brought to a pediatrician due to feeding difficulty for the last 4 days. Her mother mentions that the infant breathes rapidly and sweats profusely while nursing. She has been drinking very little breast milk and stops feeding as if she is tired, only to start sucking again after a few minutes. There is no history of cough, sneezing, nasal congestion, or fever. She was born at full term and her birth weight was 3.2 kg (7.0 lb). Her temperature is 37.0°C (98.6°F), pulse rate is 190/min, and respiratory rate is 64/min. On chest auscultation, bilateral wheezing is present. A precordial murmur starts immediately after the onset of the first heart sound (S1), reaching its maximal intensity at the end of systole, and waning during late diastole. The murmur is best heard over the second left intercostal space and radiates to the left clavicle. The first heart sound (S1) is normal, while the second heart sound (S2) is obscured by the murmur. Which of the following is the most likely diagnosis?
A. Patent ductus arteriosus (Correct Answer)
B. Aortopulmonary window
C. Supracristal ventricular septal defect with aortic regurgitation
D. Congenital mitral insufficiency
E. Ruptured congenital sinus of Valsalva aneurysm
Explanation: ***Patent ductus arteriosus***
- The continuous "machinery-like" murmur heard throughout systole and diastole, loudest at the **second left intercostal space** and radiating to the **left clavicle**, is classic for a PDA.
- Symptoms of **feeding difficulty**, **tachypnea**, and **diaphoresis** indicate heart failure due to increased pulmonary blood flow, consistent with a significant PDA.
*Aortopulmonary window*
- This defect causes a **continuous murmur**, but it's typically heard more centrally, and the specific radiation to the left clavicle is less characteristic.
- While it can present with similar symptoms of heart failure, the precise murmur description points away from this diagnosis.
*Supracristal ventricular septal defect with aortic regurgitation*
- A VSD murmur is typically **holosystolic**, not continuous, and would be loudest at the lower left sternal border.
- The added aortic regurgitation would cause a diastolic murmur, but the classic "machinery-like" continuous murmur is not characteristic.
*Congenital mitral insufficiency*
- **Mitral insufficiency** would cause a **holosystolic murmur** loudest at the apex and radiating to the axilla, which does not match the description.
- The murmur in this condition would not be continuous throughout systole and diastole.
*Ruptured congenital sinus of Valsalva aneurysm*
- A ruptured sinus of Valsalva aneurysm usually presents with **sudden onset chest pain** and acute heart failure symptoms in an older child or adult.
- While it can cause a continuous murmur, the presentation in a 6-week-old without acute distress is less likely.
Question 45: A 26-year-old woman with poor prenatal care and minimal antenatal screening presents to the emergency department in labor. Shortly thereafter, she delivers a baby girl who subsequently demonstrates symptoms of chorioretinitis on examination. A series of postpartum screening questions is significant only for the presence of multiple cats in the mother’s household. The clinical team orders an enhanced MRI examination of the infant’s brain which reveals hydrocephalus, multiple punctate intracranial calcifications, and 2 sub-cortical ring-enhancing lesions. Which is the most likely diagnosis?
A. Rubella
B. Syphilis
C. CMV
D. HSV
E. Toxoplasmosis (Correct Answer)
Explanation: ***Toxoplasmosis***
- The triad of **chorioretinitis**, **hydrocephalus**, and **intracranial calcifications** is classic for congenital toxoplasmosis.
- The mother's exposure to **cats** (definitive hosts) and poor prenatal care supports the diagnosis of an acute maternal infection with vertical transmission.
*Rubella*
- Congenital rubella presents with **sensorineural hearing loss**, **cardiac defects** (e.g., patent ductus arteriosus, pulmonary artery stenosis), and **cataracts**, not chorioretinitis and intracranial calcifications.
- While it can cause microcephaly, the specific **hydrocephalus** and diffuse calcifications seen here are not typical.
*Syphilis*
- Congenital syphilis manifests with early symptoms like **hepatosplenomegaly**, **rash**, and **rhinitis**, and later signs such as **Hutchinson's teeth** and **saddle nose**.
- **Chorioretinitis** and the specific pattern of **intracranial calcifications** observed are not characteristic features of congenital syphilis.
*CMV*
- Congenital cytomegalovirus (CMV) often causes **periventricular calcifications**, **microcephaly**, and **sensorineural hearing loss**, but typically not the diffuse punctate calcifications and subcortical ring-enhancing lesions seen in this case.
- While chorioretinitis can occur, the overall clinical picture with **hydrocephalus** points away from CMV as the most likely diagnosis.
*HSV*
- Congenital herpes simplex virus (HSV) infection typically presents with **skin vesicles**, **keratoconjunctivitis**, and encephalitis, often with focal brain lesions.
- The lack of skin lesions and the specific pattern of diffuse **intracranial calcifications** and **chorioretinitis** make HSV less likely.
Question 46: A 2-year-old boy is brought to a pediatrician because his parents have noticed that he seems to be getting tired very easily at home. Specifically, they have noticed that he is often panting for breath after walking around the house for a few minutes and that he needs to take naps fairly often throughout the day. He has otherwise been well, and his parents do not recall any recent infections. He was born at home, and his mom did not receive any prenatal care prior to birth. Physical exam reveals a high-pitched, harsh, holosystolic murmur that is best heard at the lower left sternal border. No cyanosis is observed. Which of the following oxygen tension profiles would most likely be seen in this patient? (LV = left ventricle, RV = right ventricle, and SC = systemic circulation).
A. LV: normal, RV: normal, SC: normal
B. LV: normal, RV: increased, SC: normal (Correct Answer)
C. LV: decreased, RV: increased, SC: decreased
D. LV: decreased, RV: normal, SC: decreased
E. LV: normal, RV: normal, SC: decreased
Explanation: ***LV: normal, RV: increased, SC: normal***
- The patient's presentation with easy fatigability, dyspnea on exertion, and a **holosystolic murmur** at the **lower left sternal border** strongly suggests a **ventricular septal defect (VSD)**. These symptoms result from a **left-to-right shunt**, leading to increased blood flow and pressure in the **right ventricle (RV)** and pulmonary circulation.
- In a VSD, highly oxygenated blood from the **left ventricle (LV)** shunts into the RV. This increases the **oxygen tension** in the RV, while the LV and systemic circulation (SC) typically maintain normal oxygen tension if the shunt is not so large that it causes **pulmonary hypertension** with **Eisenmenger syndrome**.
*LV: normal, RV: normal, SC: normal*
- This profile would indicate a **normal cardiovascular system** without any significant shunting or cardiac anomaly.
- It does not align with the patient's symptoms of easy fatigability, dyspnea, and the presence of a pathological murmur.
*LV: decreased, RV: increased, SC: decreased*
- A **decreased oxygen tension in the left ventricle** and **systemic circulation** typically indicates a **right-to-left shunt** or severe **pulmonary disease**, often associated with **cyanosis**, which is noted as absent in this patient.
- While RV oxygen tension *could* be increased in some complex congenital heart diseases with right-to-left shunting (e.g., mixing lesions), the overall profile does not fit the characteristic presentation of a VSD without cyanosis.
*LV: decreased, RV: normal, SC: decreased*
- This profile with **decreased oxygen tension in the left ventricle** and **systemic circulation** suggests a condition where oxygenated blood supply to the systemic circulation is compromised, such as severe **left ventricular dysfunction** or a **right-to-left shunt**.
- A **normal RV oxygen tension** without **cyanosis** makes this unlikely in the context of the patient's symptoms.
*LV: normal, RV: normal, SC: decreased*
- A **decreased oxygen tension in the systemic circulation** with **normal LV and RV oxygen tension** is inconsistent with a **VSD**.
- This profile might be observed in conditions like severe **anemia** or **hypoxia** without a primary cardiac shunt.
Question 47: A child is born by routine delivery and quickly develops respiratory distress. He is noted to have epicanthal folds, low-set ears that are pressed against his head, widely set eyes, a broad, flat nose, clubbed feet, and a receding chin. The mother had one prenatal visit, at which time the routine ultrasound revealed an amniotic fluid index of 3 cm. What is the most likely underlying cause of this patient's condition?
A. Unilateral renal agenesis
B. An extra 18th chromosome
C. Autosomal recessive polycystic kidney disease (ARPKD)
D. A microdeletion in chromosome 22
E. Bilateral renal agenesis (Correct Answer)
Explanation: ***Bilateral renal agenesis***
- The combination of **amniotic fluid index (AFI) of 3 cm** (indicating **oligohydramnios**) and multiple facial and limb anomalies strongly suggests **Potter sequence**.
- **Bilateral renal agenesis** is the most common cause of **Potter sequence**, leading to absence of fetal urine production and subsequent oligohydramnios, which restricts fetal movement and lung development.
*Unilateral renal agenesis*
- **Unilateral renal agenesis** typically does not cause **oligohydramnios** because the single functioning kidney can produce sufficient urine.
- While it can be associated with other anomalies, the severe extent of Potter sequence features described here is unlikely with only unilateral involvement.
*An extra 18th chromosome*
- An extra 18th chromosome refers to **Edwards syndrome (Trisomy 18)**, which presents with severe intellectual disability, micrognathia, prominent occiput, and rocker-bottom feet.
- While Edwards syndrome is associated with a variety of anomalies, including renal issues, the constellation of features (especially the clear link to oligohydramnios and respiratory distress) points more directly to Potter sequence.
*Autosomal recessive polycystic kidney disease (ARPKD)*
- **ARPKD** causes **enlarged, cystic kidneys** and can lead to **oligohydramnios** and respiratory distress due to renal insufficiency.
- However, the description of **epicanthal folds, low-set ears, widely set eyes, and a broad, flat nose** is more characteristic of the **Potter facies** seen in severe oligohydramnios, rather than specific to ARPKD itself.
*A microdeletion in chromosome 22*
- A microdeletion in chromosome 22 typically refers to **22q11.2 deletion syndrome (DiGeorge syndrome)**, which is associated with **cardiac defects**, **abnormal facies**, **thymic hypoplasia**, **cleft palate**, and **hypocalcemia**.
- While renal anomalies can occur in DiGeorge syndrome, the primary presentation is not characterized by the severe oligohydramnios and classic Potter sequence features described.
Question 48: A 3-day-old female newborn delivered vaginally at 36 weeks to a 27-year-old woman has generalized convulsions lasting 3 minutes. Prior to the event, she was lethargic and had difficulty feeding. The infant has two healthy older siblings and the mother's immunizations are up-to-date. The infant appears icteric. The infant's weight and length are at the 5th percentile, and her head circumference is at the 99th percentile for gestational age. There are several purpura of the skin. Ocular examination shows posterior uveitis. Cranial ultrasonography shows ventricular dilatation, as well as hyperechoic foci within the cortex, basal ganglia, and periventricular region. Which of the following is the most likely diagnosis?
A. Congenital parvovirus infection
B. Congenital Toxoplasma gondii infection (Correct Answer)
C. Congenital Treponema pallidum infection
D. Congenital cytomegalovirus infection
E. Congenital rubella infection
Explanation: ***Congenital Toxoplasma gondii infection***
- **Ventricular dilatation** with widespread **hyperechoic foci** (calcifications) in the brain, along with **posterior uveitis**, highly suggests congenital toxoplasmosis.
- Other features like **generalized convulsions**, **icterus**, **purpura**, and **microcephaly** (indicated by 5th percentile weight/length vs 99th percentile head circumference discrepancy suggesting hydrocephalus with macrocephaly) are also consistent with this diagnosis.
*Congenital parvovirus infection*
- Primarily causes severe **anemia**, **hydrops fetalis**, and **myocarditis**; it does not typically present with extensive cerebral calcifications or uveitis.
- While it can lead to neurological issues, the specific brain imaging findings and ocular involvement described are not characteristic.
*Congenital Treponema pallidum infection*
- Characterized by rhinitis (**snuffles**), **hepatosplenomegaly**, **bone abnormalities** (e.g., osteochondritis), and **rash**.
- While it can cause CNS involvement and developmental delays, the distinct pattern of brain calcifications and uveitis is not typical.
*Congenital cytomegalovirus infection*
- Can cause **periventricular calcifications**, but the widespread, diffuse calcifications (cortex, basal ganglia, periventricular) are less typical than with toxoplasmosis, which often shows more diffuse parenchymal calcifications.
- While it shares features like small for gestational age, icterus, and purpura, **posterior uveitis** is more strongly associated with toxoplasmosis.
*Congenital rubella infection*
- Classic triad includes **cataracts** (or glaucoma), **sensorineural hearing loss**, and **congenital heart defects** (e.g., PDA, pulmonary artery stenosis).
- While CNS involvement (e.g., intellectual disability, microcephaly) can occur, the widespread cerebral calcifications and posterior uveitis are not characteristic.
Question 49: A 9-year-old boy is brought to the physician because his parents are concerned that he has been unable to keep up with his classmates at school. He is at the 4th percentile for height and at the 15th percentile for weight. Physical examination shows dysmorphic facial features. Psychologic testing shows impaired intellectual and adaptive functions. Genetic analysis shows a deletion of the long arm of chromosome 7. Which of the following is the most likely additional finding in this patient?
A. Absent thymus gland
B. Supravalvular aortic stenosis (Correct Answer)
C. Brushfield spots on the iris
D. Testicular enlargement
E. Hand flapping movements
Explanation: ***Supravalvular aortic stenosis***
- The clinical presentation, including **dysmorphic facial features**, **growth restriction**, and **intellectual disability**, coupled with a **deletion on the long arm of chromosome 7**, is highly suggestive of **Williams syndrome**.
- **Supravalvular aortic stenosis** is a classic cardiovascular finding in **Williams syndrome**, present in about 75% of affected individuals.
*Absent thymus gland*
- An absent thymus gland is characteristic of **DiGeorge syndrome**, which is caused by a **deletion on chromosome 22q11**.
- This patient's genetic analysis indicates a deletion on **chromosome 7**, not chromosome 22.
*Brushfield spots on the iris*
- **Brushfield spots** are characteristic of **Down syndrome** (**trisomy 21**).
- The genetic finding of a **deletion on chromosome 7** rules out Down syndrome as the underlying cause.
*Testicular enlargement*
- **Testicular enlargement** is a hallmark feature of **Fragile X syndrome**, a genetic condition caused by an **FMR1 gene mutation** on the X chromosome.
- This patient's symptoms and genetic findings of a **chromosome 7 deletion** are not consistent with Fragile X syndrome.
*Hand flapping movements*
- **Hand flapping** is a common repetitive behavior observed in individuals with **autism spectrum disorder** and is also seen in some other genetic conditions like **Rett syndrome**.
- While individuals with Williams syndrome may have unique behavioral profiles, hand flapping is not a specific or typical feature of the syndrome, and the genetic finding points to Williams syndrome.
Question 50: A 4-year-old boy is brought to the physician by his parents for a well-child examination. He has been healthy and has met all development milestones. His immunizations are up-to-date. He is at the 97th percentile for height and 50th percentile for weight. His vital signs are within normal limits. The lungs are clear to auscultation. Auscultation of the heart shows a high-frequency, midsystolic click that is best heard at the fifth left intercostal space. Oral examination shows a high-arched palate. He has abnormally long, slender fingers and toes. The patient is asked to clasp the wrist of the opposite hand and the little finger and thumb overlap. Slit lamp examination shows superotemporal lens subluxation bilaterally. Which of the following is the most appropriate next step in management?
A. Karyotyping
B. IGF-1 measurement
C. Thyroid biopsy
D. Measure plasma homocysteine concentration
E. Echocardiography (Correct Answer)
Explanation: ***Echocardiography***
- This patient presents with classic signs of **Marfan syndrome**, including tall stature, high-arched palate, arachnodactyly (**positive wrist and thumb signs**), and **ectopia lentis** (lens subluxation).
- Patients with Marfan syndrome are at increased risk for **aortic dilation**, **aneurysm formation**, and **dissection**, which can be identified and monitored through echocardiography.
*Karyotyping*
- **Chromosomal abnormalities** typically manifest with more global developmental delays and dysmorphic features which are not the primary concern here.
- While Marfan syndrome is a genetic disorder, it's caused by a mutation in the *FBN1* gene, not a large chromosomal aberration detectable by standard karyotyping.
*IGF-1 measurement*
- **IGF-1 (insulin-like growth factor 1)** levels are used to assess for **growth hormone disorders**, such as gigantism or acromegaly.
- While the patient is tall, his other features (arachnodactyly, ectopia lentis, cardiac murmur) are not consistent with **growth hormone excess**.
*Thyroid biopsy*
- **Thyroid biopsy** is indicated for the evaluation of **thyroid nodules** or suspicious masses to rule out malignancy.
- This patient has no clinical signs or symptoms suggestive of a thyroid disorder.
*Measure plasma homocysteine concentration*
- Elevated **homocysteine levels** are characteristic of **homocystinuria**, a genetic disorder that can present with some similar features to Marfan syndrome, such as lens subluxation and skeletal abnormalities.
- However, homocystinuria typically involves **downward lens subluxation**, intellectual disability, and a higher risk of **thrombotic events**, which are not described in this patient.
