Chromosomal disorders — MCQs

A 16-year-old girl is brought to the physician because she has not yet had her 1st period. She was born at 39 weeks gestation via spontaneous vaginal delivery. She is up to date on all vaccines and meeting all developmental milestones. She has no history of a serious illness and takes no medications. Physical examination shows underdeveloped breasts with scant pubic and axillary hair. Speculum examination shows a short vagina and no cervix. The remainder of the physical examination shows no abnormalities. Pelvic ultrasound shows no uterus. Which of the following is the most likely karyotype in this patient?

A 5-year-old boy is brought to the physician because of behavioral problems. His mother says that he has frequent angry outbursts and gets into fights with his classmates. He constantly complains of feeling hungry, even after eating a full meal. He has no siblings, and both of his parents are healthy. He is at the 25th percentile for height and is above the 95th percentile for weight. Physical examination shows central obesity, undescended testes, almond-shaped eyes, and a thin upper lip. Which of the following genetic changes is most likely associated with this patient's condition?

A 19-year-old male from rural West Virginia presents to his family medicine doctor to discuss why he is having trouble getting his wife pregnant. On exam, he is 6 feet 2 inches with a frail frame and broad hips for a male his size. He is noted to have mild gynecomastia, no facial hair, and small, underdeveloped testes. He claims that although he has a lower libido than most of his friends, he does have unprotected sex with his wife. His past medical history is notable for developmental delay and difficulties in school. What is the most likely chromosomal abnormality in this patient?

A 36-year-old G4P0A3 woman presents at the prenatal diagnostic center at 18 weeks of gestation for the scheduled fetal anomaly scan. The patient's past medical history reveals spontaneous abortions. She reports that her 1st, 2nd, and 3rd pregnancy losses occurred at 8, 10, and 12 weeks of gestation, respectively. Ultrasonography indicates a female fetus with cystic hygroma (measuring 4 cm x 5 cm in size) and fetal hydrops. Which of the following karyotypes does her fetus most likely carry?

A 1-week-old baby is brought to the pediatrician’s office for a routine checkup. On examination, she is observed to have microcephaly with a prominent occiput. She also has clenched fists and rocker-bottom feet with prominent calcanei. A cardiac murmur is evident on auscultation. Based on the clinical findings, a diagnosis of nondisjunction of chromosome 18 is suspected. The pediatrician orders a karyotype for confirmation. He goes on to explain to the mother that her child will face severe growth difficulties. Even if her daughter progresses beyond a few months, she will not be able to reach developmental milestones at the appropriate age. In addition to the above, which of the following is most likely a consequence of this genetic disturbance?

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 6-year-old male presents to the pediatrician with seizures. His mother reports that the patient has had two seizures lasting about 30 seconds each over the last three days. She reports that the patient has previously had seizures a few times per year since he was 12 months of age. The patient’s past medical history is otherwise notable for intellectual disability. He rolled over at 14 months of age and walked at 24 months of age. The patient’s mother denies any family history of epilepsy or other neurologic diseases. The patient is in the 3rd percentile for height and the 15th percentile for weight. On physical exam, he has a happy demeanor with frequent smiling. The patient has strabismus and an ataxic gait accompanied by flapping of the hands. He responds intermittently to questions with one-word answers. This patient is most likely to have which of the following genetic abnormalities?

A 5-year-old boy is brought to a pediatrician by his parents for evaluation of learning difficulties in school. He has short stature, a flat face, low-set ears, a large tongue, and a single line on the palm. He was born to his parents after 20 years of marriage. You ordered karyotyping which will likely reveal which of the following?

A 15-year-old boy is brought to the physician by his mother for a well-child examination. He recently stopped attending his swim classes. The patient is at the 97th percentile for height and the 50th percentile for weight. Examination shows decreased facial hair, bilateral breast enlargement, and long extremities. Genital examination shows scant pubic hair, small testes, and a normal-sized penis. Further evaluation is most likely to show which of the following karyotypes?

A newborn male is evaluated in the hospital nursery two hours after birth. The patient was born at 39 weeks of gestation to a 30-year-old primigravid via vaginal delivery. The patient’s mother received routine prenatal care, and the pregnancy was uncomplicated. The patient’s anatomy ultrasound at 20 weeks of gestation was unremarkable. The patient’s mother denies any family history of genetic diseases. The patient’s Apgar scores were notable for poor muscle tone at both one and five minutes of life. The patient’s birth weight is 2.6 kg (5 lb 11 oz), which is at the 5th percentile. His height and head circumference are in the 15th and 3rd percentile, respectively. On physical exam, the patient has a wide nasal bridge, downslanting palpebral fissures, and widely spaced eyes. He has good respiratory effort with a high-pitched cry. This patient is most likely to have experienced a deletion on which of the following chromosomes?