Developmental regression causes US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Developmental regression causes. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Developmental regression causes US Medical PG Question 1: An 18-month-old girl is brought to the pediatrician’s office for failure to thrive and developmental delay. The patient’s mother says she has not started speaking and is just now starting to pull herself up to standing position. Furthermore, her movement appears to be restricted. Physical examination reveals coarse facial features and restricted joint mobility. Laboratory studies show increased plasma levels of several enzymes. Which of the following is the underlying biochemical defect in this patient?
- A. Congenital lack of lysosomal formation
- B. Inappropriate protein targeting to endoplasmic reticulum
- C. Failure of mannose phosphorylation (Correct Answer)
- D. Inappropriate degradation of lysosomal enzymes
- E. Misfolding of nuclear proteins
Developmental regression causes Explanation: ***Failure of mannose phosphorylation***
- The constellation of **failure to thrive**, **developmental delay**, **coarse facial features**, restricted joint mobility, and elevated plasma enzymes in an 18-month-old girl is highly suggestive of **I-cell disease** (mucolipidosis type II).
- **I-cell disease** is caused by the deficiency of **N-acetylglucosaminyl-1-phosphotransferase**, an enzyme responsible for phosphorylating mannose residues on lysosomal enzymes, which is crucial for proper targeting to the lysosome.
*Congenital lack of lysosomal formation*
- **Lysosomes** are present in this condition, but their enzymes are misdirected.
- A congenital lack of lysosomal formation would present with even more severe and widespread cellular dysfunction, possibly incompatible with life beyond early embryonic stages.
*Inappropriate protein targeting to endoplasmic reticulum*
- Proteins destined for the endoplasmic reticulum (ER) are typically targeted by an N-terminal signal peptide and then processed within the ER.
- While ER dysfunction can cause various disorders, the specific symptoms and enzyme elevations point away from a primary ER targeting defect related to lysosomal enzymes.
*Inappropriate degradation of lysosomal enzymes*
- In I-cell disease, lysosomal enzymes are synthesized but are **not properly targeted to the lysosomes**; instead, they are secreted into the bloodstream, leading to their elevated plasma levels.
- While some degradation might occur, the primary issue is mis-packaging and secretion, not increased degradation within the cell.
*Misfolding of nuclear proteins*
- Misfolding of nuclear proteins can lead to a variety of genetic disorders and cellular stress responses, but the clinical presentation, particularly the accumulation of undegraded material and elevated plasma lysosomal enzymes, is not characteristic of primary nuclear protein misfolding.
- The pathology in I-cell disease centers on lysosomal dysfunction rather than nuclear protein abnormalities.
Developmental regression causes US Medical PG Question 2: A 21-year-old female presents to her obstetrician because she has stopped getting her period, after being irregular for the last 3 months. Upon further questioning, the patient reveals that she has had a 17 lb. unintended weight loss, endorses chronic diarrhea, abdominal pain, and constipation that waxes and wanes. Family history is notable only for an older brother with Type 1 Diabetes. She is healthy, and is eager to gain back some weight. Her OBGYN refers her to a gastroenterologist, but first sends serology laboratory studies for IgA anti-tissue transglutaminase antibodies (IgA-tTG). These results come back positive at > 10x the upper limit of normal. Which of the following is the gastroenterologist likely to find on endoscopy and duodenal biopsy?
- A. Friable mucosal pseudopolyps with biopsy notable for crypt abscesses
- B. Cobblestoning with biopsy showing transmural inflammation and noncaseating granulomas
- C. Villous atrophy with crypt lengthening and intraepithelial lymphocytes (Correct Answer)
- D. Foamy macrophages, which stain PAS positive
- E. Normal appearing villi and biopsy
Developmental regression causes Explanation: ***Villous atrophy with crypt lengthening and intraepithelial lymphocytes***
- The patient's symptoms (amenorrhea, weight loss, diarrhea, abdominal pain, constipation) combined with a **positive IgA anti-tissue transglutaminase antibody (IgA-tTG)** strongly suggest **celiac disease**.
- The characteristic endoscopic and histological findings in celiac disease are **villous atrophy**, **crypt hyperplasia (lengthening)**, and increased **intraepithelial lymphocytes** in the small intestine.
*Friable mucosal pseudopolyps with biopsy notable for crypt abscesses*
- This description is characteristic of **ulcerative colitis**, an inflammatory bowel disease, which typically causes **bloody diarrhea** and is not associated with positive IgA-tTG antibodies.
- **Pseudopolyps** result from cycles of ulceration and regeneration, and **crypt abscesses** are hallmarks of active inflammation in ulcerative colitis.
*Cobblestoning with biopsy showing transmural inflammation and noncaseating granulomas*
- This describes the typical findings in **Crohn's disease**, another inflammatory bowel disease, which can cause **abdominal pain** and **diarrhea** but is not linked to IgA-tTG antibodies.
- **Transmural inflammation** means inflammation extends through all layers of the bowel wall, and **noncaseating granulomas** are a key distinguishing feature.
*Foamy macrophages, which stain PAS positive*
- These findings are characteristic of **Whipple's disease**, a rare bacterial infection caused by *Tropheryma whipplei*.
- While Whipple's disease can present with **malabsorption** and **weight loss**, it is not associated with positive celiac serology.
*Normal appearing villi and biopsy*
- Given the patient's strong clinical suspicion for celiac disease and a **highly positive IgA-tTG** test, normal findings on endoscopy and biopsy would be highly unlikely.
- A definitive diagnosis of celiac disease typically requires characteristic histological changes to confirm the serological findings.
Developmental regression causes US Medical PG Question 3: An 8-month-old boy is brought to the physician by his parents for gradually increasing loss of neck control and inability to roll over for the past 2 months. During this time, he has had multiple episodes of unresponsiveness with a blank stare and fluttering of the eyelids. His parents state that he sometimes does not turn when called but gets startled by loud noises. He does not maintain eye contact. He was able to roll over from front to back at 5 months of age and has not yet begun to sit or crawl. His parents are of Ashkenazi Jewish descent. Neurological examination shows generalized hypotonia. Deep tendon reflexes are 3+ bilaterally. Plantar reflex shows extensor response bilaterally. Fundoscopy shows bright red macular spots bilaterally. The remainder of the examination shows no abnormalities. Which of the following is the most likely cause of this patient's symptoms?
- A. Sphingomyelinase deficiency
- B. β-glucocerebrosidase deficiency
- C. α-galactosidase A deficiency
- D. ATP-binding cassette transporter mutation
- E. β-hexosaminidase A deficiency (Correct Answer)
Developmental regression causes Explanation: ***β-hexosaminidase A deficiency***
- The constellation of **developmental regression** (loss of neck control, inability to roll over), **hypotonia**, **exaggerated startle response**, **cherry-red macular spots**, and **Ashkenazi Jewish descent** is classic for **Tay-Sachs disease**, which is caused by a deficiency in β-hexosaminidase A.
- The patient's seizures ("unresponsiveness with a blank stare and fluttering of the eyelids") and **hyperreflexia** (3+ deep tendon reflexes, extensor plantar response) are also consistent with the progressive neurodegeneration seen in Tay-Sachs disease.
*Sphingomyelinase deficiency*
- This deficiency causes **Niemann-Pick disease**, which can also present with **developmental regression**, **hypotonia**, and **cherry-red macular spots**.
- However, Niemann-Pick disease typically involves **hepatosplenomegaly** and **pulmonary involvement**, which are not mentioned in this patient's presentation.
*β-glucocerebrosidase deficiency*
- This deficiency leads to **Gaucher disease**, characterized by **hepatosplenomegaly**, **bone crises**, and cytopenias.
- While some forms can have neurological symptoms, the classic cherry-red spot and pronounced developmental regression as described are not typical of Gaucher disease.
*α-galactosidase A deficiency*
- This deficiency causes **Fabry disease**, which is an **X-linked lysosomal storage disorder** presenting with **neuropathic pain**, **angiokeratomas**, **renal disease**, and **cardiac involvement** in adolescence or adulthood.
- It does not present with infantile neurodegeneration or cherry-red spots.
*ATP-binding cassette transporter mutation*
- Mutations in ABC transporters can lead to various disorders, such as **adrenoleukodystrophy** (deficiency in VLCFA transport) or **cystic fibrosis**.
- These conditions do not present with the specific combination of symptoms, especially the cherry-red macula and profound developmental regression, seen in this infant.
Developmental regression causes US Medical PG Question 4: An 18-month-old boy is brought to the physician for a well-child examination. His mother is concerned because he is unable to walk on his own. He has been increasingly irritable over the past month, has been feeding poorly, and has had multiple episodes of vomiting. His immunizations are up-to-date. He is at the 50th percentile for height, 40th percentile for weight, and 98th percentile for head circumference. He appears lethargic. His vital signs are within normal limits. Examination shows a bulging anterior fontanelle. The child is unable to stand without support and falls if he attempts to walk. Muscle tone is increased and deep tendon reflexes are 4+ in the lower extremities. Examination of the back is unremarkable. An MRI of the brain shows symmetrical enlargement of all four ventricles. Which of the following is the most appropriate treatment in this patient?
- A. Cerebral aqueductoplasty
- B. Acetazolamide therapy
- C. Ventriculoperitoneal shunt (Correct Answer)
- D. Furosemide therapy
- E. Serial lumbar punctures
Developmental regression causes Explanation: ***Ventriculoperitoneal shunt***
- The patient presents with symptoms and signs of **hydrocephalus** (e.g., rapidly increasing head circumference, bulging fontanelle, vomiting, irritability, gait disturbance, hypertonia, hyperreflexia). An MRI showing **symmetrical enlargement of all four ventricles** confirms communicating hydrocephalus.
- A **ventriculoperitoneal (VP) shunt** is the most appropriate long-term treatment for symptomatic hydrocephalus, diverting CSF from the ventricles to the peritoneal cavity.
*Cerebral aqueductoplasty*
- This procedure is indicated for **aqueductal stenosis**, which causes **obstructive (non-communicating) hydrocephalus**, where only the ventricles proximal to the obstruction are dilated (e.g., third and lateral ventricles).
- The MRI in this case shows **symmetrical enlargement of all four ventricles**, indicating **communicating hydrocephalus**, making aqueductoplasty unsuitable.
*Acetazolamide therapy*
- **Acetazolamide** is a carbonic anhydrase inhibitor that can reduce CSF production, typically used in cases of **idiopathic intracranial hypertension** or as a temporary measure in some forms of hydrocephalus.
- However, in a symptomatic infant with significant hydrocephalus and rapid head growth, medical therapy alone is usually insufficient for long-term management and does not address the underlying CSF drainage issue.
*Furosemide therapy*
- **Furosemide**, a loop diuretic, can also reduce CSF production but is generally not considered a primary treatment for hydrocephalus, especially in symptomatic infants.
- Its effects on CSF reduction are often transient and not as robust as surgical intervention for established hydrocephalus with neurological deficits.
*Serial lumbar punctures*
- **Serial lumbar punctures** can temporarily relieve pressure in **communicating hydrocephalus**, especially in neonates or patients awaiting shunt placement.
- However, they are not a long-term solution for symptomatic hydrocephalus in an older infant with ongoing symptoms and a need for definitive management and are associated with risks of infection and discomfort.
Developmental regression causes US Medical PG Question 5: A deficiency in which of the following lysosomal enzymes is inherited in a pattern similar to a deficiency of iduronate sulfatase (Hunter syndrome)?
- A. Sphingomyelinase
- B. Glucocerebrosidase
- C. Galactocerebrosidase
- D. Alpha-L-iduronidase
- E. Alpha-galactosidase A (Correct Answer)
Developmental regression causes Explanation: ***Alpha-galactosidase A***
- A deficiency in **alpha-galactosidase A** causes **Fabry disease**, which, like Hunter syndrome (iduronate sulfatase deficiency), is inherited in an **X-linked recessive** pattern.
- Both conditions primarily affect males, with carrier females potentially exhibiting milder symptoms.
*Sphingomyelinase*
- A deficiency in sphingomyelinase leads to **Niemann-Pick disease types A and B**, which are inherited in an **autosomal recessive** pattern.
- This mode of inheritance differs from the X-linked pattern of Hunter syndrome.
*Glucocerebrosidase*
- A deficiency in glucocerebrosidase causes **Gaucher disease**, inherited in an **autosomal recessive** pattern.
- This is a common lysosomal storage disorder, but its inheritance pattern is distinct from X-linked disorders.
*Galactocerebrosidase*
- A deficiency in galactocerebrosidase causes **Krabbe disease (globoid cell leukodystrophy)**, which is inherited in an **autosomal recessive** pattern.
- Krabbe disease is a severe neurodegenerative disorder, but its genetic transmission is not X-linked.
*Alpha-L-iduronidase*
- A deficiency in **alpha-L-iduronidase** causes **Hurler syndrome (MPS I)**, which is inherited in an **autosomal recessive** pattern.
- While both Hunter and Hurler syndromes are mucopolysaccharidoses, their genetic inheritance patterns are different.
Developmental regression causes US Medical PG Question 6: A 6-month-old boy is referred to a geneticist after he is found to have persistent hypotonia and failure to thrive. He has also had episodes of what appears to be respiratory distress and has an enlarged heart on physical exam. There is a family history of childhood onset hypertrophic cardiomyopathy, so a biopsy is performed showing electron dense granules within the lysosomes. Genetic testing is performed showing a defect in glycogen processing. A deficiency in which of the following enzymes is most likely to be responsible for this patient's symptoms?
- A. Lysosomal alpha 1,4-glucosidase (Correct Answer)
- B. Branching enzyme
- C. Muscle phosphorylase
- D. Debranching enzyme
- E. Glucose-6-phosphatase
Developmental regression causes Explanation: ***Lysosomal alpha 1,4-glucosidase***
- The constellation of **hypotonia**, **failure to thrive**, **respiratory distress**, and **cardiomegaly** in an infant, along with **electron-dense granules in lysosomes** and a defect in **glycogen processing**, is characteristic of **Pompe disease (Type II glycogen storage disease)**.
- **Pompe disease** is caused by a deficiency of **lysosomal alpha 1,4-glucosidase** (also known as acid maltase), which is responsible for breaking down glycogen in lysosomes.
*Branching enzyme*
- A deficiency in **branching enzyme (amylo-alpha-1,4-to-alpha-1,6-transglucosidase)** causes **Andersen disease (Type IV glycogen storage disease)**, which typically presents with **hepatosplenomegaly**, **cirrhosis**, and **failure to thrive**.
- While it involves glycogenopathy, the specific features of **cardiomyopathy** and **lysosomal accumulation** are not primary to this disorder.
*Muscle phosphorylase*
- A deficiency in **muscle phosphorylase** causes **McArdle disease (Type V glycogen storage disease)**, which primarily affects **skeletal muscle**.
- Symptoms include **exercise intolerance**, **muscle cramps**, and **myoglobinuria**, typically presenting later in childhood or adolescence, and does not involve cardiomyopathy or lysosomal storage.
*Debranching enzyme*
- A deficiency in **debranching enzyme (alpha-1,6-glucosidase)** causes **Cori disease (Type III glycogen storage disease)**, which presents with **hepatomegaly**, **hypoglycemia**, and **muscle weakness**.
- While it can sometimes involve a milder form of cardiomyopathy, the significant **lysosomal involvement** and severe infantile onset with respiratory distress and profound hypotonia point away from Cori disease.
*Glucose-6-phosphatase*
- A deficiency in **glucose-6-phosphatase** causes **Von Gierke disease (Type I glycogen storage disease)**, characterized by **severe fasting hypoglycemia**, **lactic acidosis**, **hepatomegaly**, and **hyperlipidemia**.
- This condition primarily affects the liver and kidneys, and typically does not present with primary cardiomyopathy, hypotonia, or lysosomal glycogen accumulation.
Developmental regression causes US Medical PG Question 7: A 6-year-old boy presents to the pediatrician with his parents. He is fully vaccinated and met most developmental milestones. His fine motor milestones are delayed; at present, he cannot eat by himself and has difficulty in self-dressing. His intelligence quotient (IQ) is 65. He listens quietly while spoken to and engages in play with his classmates. He neither talks excessively nor remains mute, but engages in normal social conversation. There is no history of seizures and he is not on any long-term medical treatment. On his physical examination, his vital signs are stable. His height and weight are normal for his age and sex, but his occipitofrontal circumference is less than the 3rd percentile for his age and sex. His neurologic examination is also normal. Which of the following is the most likely diagnosis?
- A. Attention deficit hyperactivity disorder
- B. Autism
- C. Intellectual disability (Correct Answer)
- D. Obsessive-compulsive disorder
- E. Tic disorder
Developmental regression causes Explanation: ***Intellectual disability***
- The boy's **IQ of 65** falls below the diagnostic threshold of 70 for intellectual disability, and he exhibits **adaptive deficits** in fine motor skills (difficulty eating and dressing) and **developmental delays**.
- His **microcephaly (occipitofrontal circumference less than 3rd percentile)** is also associated with certain forms of intellectual disability, further supporting this diagnosis.
*Attention deficit hyperactivity disorder*
- This condition is characterized by **inattention, hyperactivity, and impulsivity**, none of which are prominently described in the boy's presentation (he listens quietly and engages in normal conversation).
- While academic difficulties might occur, **significant adaptive and intellectual delays** as described are not typical primary features of ADHD.
*Autism*
- Autism spectrum disorder involves persistent deficits in **social communication and interaction** and **restricted, repetitive patterns of behavior, interests, or activities**.
- The boy's ability to engage in "normal social conversation" and play with classmates, along with an absence of repetitive behaviors or restricted interests, makes autism less likely.
*Obsessive-compulsive disorder*
- OCD is characterized by the presence of **obsessions (recurrent, persistent thoughts, urges, or images)** and/or **compulsions (repetitive behaviors or mental acts)**.
- The boy's symptoms do not include any mention of obsessions or compulsions.
*Tic disorder*
- Tic disorders involve **sudden, rapid, recurrent, nonrhythmic motor movements or vocalizations**.
- There is no mention of tics in the boy's presentation, making this diagnosis unlikely.
Developmental regression causes US Medical PG Question 8: A 3-year-old girl is brought to the physician for a well-child examination. She was born at term and has been healthy since. She can climb up and down the stairs and can pedal a tricycle. She has difficulty using a spoon to feed herself but can copy a line. She speaks in 2- to 3-word sentences that can be understood by most people. She is selfish while playing with children her age and throws tantrums quite often. She cannot put on her own shoes and socks. She does not tolerate separation from her parents. She is at 60th percentile for height and weight. Physical examination including neurologic examination reveals no abnormalities. Which of the following is the most appropriate assessment of her development?
- A. Fine motor: Normal | Gross motor: Normal | Language: Delayed | Social skills: Delayed
- B. Fine motor: Delayed | Gross motor: Delayed | Language: Normal | Social skills: Normal
- C. Fine motor: Delayed | Gross motor: Normal | Language: Normal | Social skills: Delayed (Correct Answer)
- D. Fine motor: Normal | Gross motor: Delayed | Language: Normal | Social skills: Delayed
- E. Fine motor: Normal | Gross motor: Delayed | Language: Delayed | Social skills: Normal
Developmental regression causes Explanation: ***Fine motor: Delayed | Gross motor: Normal | Language: Normal | Social skills: Delayed***
- The child can copy a line (expected at 3 years) and climb stairs and pedal a tricycle (expected for a 3-year-old), indicating **normal gross motor skills**. However, difficulty using a spoon and putting on shoes/socks suggests **delayed fine motor skills**.
- Speaking in 2- to 3-word sentences understood by most (expected for 2-3 years) indicates **normal language development**. Being selfish and throwing tantrums (normal for 2-3 years) but not tolerating separation (suggests earlier developmental stage for separation anxiety) point to **delayed social skills**.
*Fine motor: Normal | Gross motor: Normal | Language: Delayed | Social skills: Delayed*
- This option incorrectly assesses fine motor skills as normal when the child struggles with tasks like using a spoon and dressing herself.
- While language and social skills are correctly identified as delayed, the overall assessment of fine motor makes this option incorrect.
*Fine motor: Delayed | Gross motor: Delayed | Language: Normal | Social skills: Normal*
- This option incorrectly assesses gross motor skills as delayed, despite the child's ability to climb stairs and pedal a tricycle, which are age-appropriate.
- It also incorrectly assesses social skills as normal, overlooking the persistent separation anxiety and aggressive social play for her age.
*Fine motor: Normal | Gross motor: Delayed | Language: Normal | Social skills: Delayed*
- This option incorrectly describes fine motor skills as normal and gross motor skills as delayed.
- Her ability to pedal a tricycle and climb stairs indicates age-appropriate gross motor development, while her difficulty with a spoon suggests delayed fine motor skills.
*Fine motor: Normal | Gross motor: Delayed | Language: Delayed | Social skills: Normal*
- This option incorrectly states that both fine motor and gross motor skills are affected and also mischaracterizes social skills as normal.
- The child's language development is within the normal range for a 3-year-old, and her social behavior, particularly the separation anxiety, indicates a delay.
Developmental regression causes US Medical PG Question 9: A 28-year-old male presents to his primary care physician with complaints of intermittent abdominal pain and alternating bouts of constipation and diarrhea. His medical chart is not significant for any past medical problems or prior surgeries. He is not prescribed any current medications. Which of the following questions would be the most useful next question in eliciting further history from this patient?
- A. "Does the diarrhea typically precede the constipation, or vice-versa?"
- B. "Is the diarrhea foul-smelling?"
- C. "Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life"
- D. "Are the symptoms worse in the morning or at night?"
- E. "Can you tell me more about the symptoms you have been experiencing?" (Correct Answer)
Developmental regression causes Explanation: ***Can you tell me more about the symptoms you have been experiencing?***
- This **open-ended question** encourages the patient to provide a **comprehensive narrative** of their symptoms, including details about onset, frequency, duration, alleviating/aggravating factors, and associated symptoms, which is crucial for diagnosis.
- In a patient presenting with vague, intermittent symptoms like alternating constipation and diarrhea, allowing them to elaborate freely can reveal important clues that might not be captured by more targeted questions.
*Does the diarrhea typically precede the constipation, or vice-versa?*
- While knowing the sequence of symptoms can be helpful in understanding the **pattern of bowel dysfunction**, it is a very specific question that might overlook other important aspects of the patient's experience.
- It prematurely narrows the focus without first obtaining a broad understanding of the patient's overall symptomatic picture.
*Is the diarrhea foul-smelling?*
- Foul-smelling diarrhea can indicate **malabsorption** or **bacterial overgrowth**, which are important to consider in some gastrointestinal conditions.
- However, this is a **specific symptom inquiry** that should follow a more general exploration of the patient's symptoms, as it may not be relevant if other crucial details are missed.
*Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life*
- Quantifying pain intensity is useful for assessing the **severity of discomfort** and monitoring changes over time.
- However, for a patient with intermittent rather than acute, severe pain, understanding the **character, location, and triggers** of the pain is often more diagnostically valuable than just a numerical rating initially.
*Are the symptoms worse in the morning or at night?*
- Diurnal variation can be relevant in certain conditions, such as inflammatory bowel diseases where nocturnal symptoms might be more concerning, or functional disorders whose symptoms might be stress-related.
- This is another **specific question** that should come after gathering a more complete initial picture of the patient's symptoms to ensure no key information is overlooked.
Developmental regression causes US Medical PG Question 10: A 15-month-old girl is brought to the pediatrician by her mother with a history of 3 episodes of breath-holding spells. The patient’s mother says that this is a new behavior and she is concerned. The patient was born at full term by spontaneous vaginal delivery with an uneventful perinatal period. She is also up to date on her vaccines. However, after the age of 6 months, the patient’s mother noticed that she was not as playful as other children of similar age. She is also not interested in interacting with others and her eye contact is poor. Her growth charts suggest that her weight, length, and head circumference were normal at birth, but there have been noticeable decelerations in weight and head circumference. On physical examination, her vital signs are normal. A neurologic examination reveals the presence of generalized mild hypotonia. She also makes repetitive hand wringing motions. Which of the following clinical features is most likely to develop in this patient during the next few years?
- A. Hemiparesis
- B. Intention tremor
- C. Absence seizures
- D. Sensorineural deafness
- E. Loss of purposeful use of her hands (Correct Answer)
Developmental regression causes Explanation: ***Loss of purposeful use of her hands***
- The constellation of symptoms—**normal development up to 6 months**, followed by **developmental regression** (loss of playfulness, poor social interaction, poor eye contact), **deceleration in head circumference**, **hypotonia**, and **repetitive hand-wringing motions**—is highly suggestive of **Rett syndrome**.
- A hallmark feature of Rett syndrome is the **loss of purposeful hand skills**, which typically occurs between 1 to 4 years of age, replaced by characteristic hand stereotypies like wringing or clapping.
*Hemiparesis*
- **Hemiparesis** is characterized by weakness on one side of the body and is not a typical feature of Rett syndrome.
- While some neurological issues occur, unilateral weakness is more indicative of focal neurological injury rather than this diffuse neurodevelopmental disorder.
*Intention tremor*
- **Intention tremor** is a type of dyskinesia that worsens during voluntary movement and is often associated with cerebellar dysfunction.
- While motor difficulties are prominent in Rett syndrome, **ataxia** and **apraxia** are more characteristic than a predominant intention tremor.
*Absence seizures*
- **Absence seizures** involve brief, sudden lapses of consciousness and are a type of generalized epilepsy.
- Although seizures are common in Rett syndrome, **generalized tonic-clonic seizures** or **focal seizures** are more frequently observed than isolated absence seizures.
*Sensorineural deafness*
- **Sensorineural deafness** implies damage to the inner ear or auditory nerve, resulting in permanent hearing loss.
- While communication difficulties are significant in Rett syndrome, they are due to speech apraxia and cognitive impairment, not primary hearing loss.
More Developmental regression causes US Medical PG questions available in the OnCourse app. Practice MCQs, flashcards, and get detailed explanations.
