A mother brings her 3-year-old son to the doctor because she is worried that he might be harming himself by constantly banging his head on the wall. He has been exhibiting this behavior for a few months. She is also worried because he has started to speak less than he used to and does not respond when his name is called. He seems aloof during playtime with other children and seems to have lost interest in most of his toys. What is the most likely diagnosis?
Q2
A 4-year-old girl presents to the office with her parents who are concerned about their daughter and slow, progressive changes in her behavior. The girl was born at 39 weeks gestation via spontaneous vaginal delivery. She is up to date on all vaccines and was meeting all developmental milestones until about 2 years ago. At one point she had a vocabulary of several words and now she verbalizes in grunts. She also flaps her hands in a repeated motion and has difficulty walking. Her parents have tried several home therapies to improve their daughter's symptoms including restricted diets, hydrotherapy, and a variety of nutritional supplements. The vital signs include: heart rate 90/min, respiratory rate 22/min, blood pressure 110/65 mm Hg, and temperature 36.9°C (98.4°F). On physical exam, she is well nourished and stares absently out the window. Her heart has a regular rate and rhythm and her lungs are clear to auscultation bilaterally. She has mild scoliosis. Which of the following is the most likely diagnosis?
Q3
A 4-year-old boy is brought to the physician because of non-fluent speech. His mother worries that his vocabulary is limited for his age and because he cannot use simple sentences to communicate. She says he enjoys playing with his peers and parents, but he has always lagged behind in his speaking and communication. His speech is frequently not understood by strangers. He physically appears normal. His height and weight are within the normal range for his age. He responds to his name, makes eye contact, and enjoys the company of his mother. Which of the following is the most appropriate next step in management?
Q4
A 3-year-old boy is brought in by his mother because she is concerned that he has been “acting differently recently”. She says he no longer seems interested in playing with his friends from preschool, and she has noticed that he has stopped making eye contact with others. In addition, she says he flaps his hands when excited or angry and only seems to enjoy playing with objects that he can place in rows or rigid patterns. Despite these behaviors, he is meeting his language goals for his age (single word use). The patient has no significant past medical history. He is at the 90th percentile for height and weight for his age. He is afebrile and his vital signs are within normal limits. A physical examination is unremarkable. Which of the following is the most likely diagnosis in this patient?
Q5
A 4-year-old girl is brought to the physician because her mother is concerned that she has been talking to an imaginary friend for 2 months. The child calls her friend 'Lucy' and says “Lucy is my best friend”. The child has multiple conversation and plays with the 'Lucy' throughout the day. The girl attends preschool regularly. She can copy a circle, tells stories, and can hop on one foot. Her maternal uncle has schizophrenia. Her parents are currently divorcing. The child's father has a history of illicit drug use. Physical examination shows no abnormalities. The mother is concerned about whether the child is acting out because of the divorce. Which of the following is the most appropriate next best step in management?
Q6
A 4-year-old girl is brought to the pediatrician by her parents after her mother recently noticed that other girls of similar age talk much more than her daughter. Her mother reports that her language development has been abnormal and she was able to use only 5–6 words at the age of 2 years. Detailed history reveals that she has never used her index finger to indicate her interest in something. She does not enjoy going to birthday parties and does not play with other children in her neighborhood. The mother reports that her favorite “game” is to repetitively flex and extend the neck of a doll, which she always keeps with her. She is sensitive to loud sounds and starts screaming excessively when exposed to them. There is no history of delayed motor development, seizures, or any other major illness; perinatal history is normal. When she enters the doctor’s office, the doctor observes that she does not look at him. When he gently calls her by her name, she does not respond to him and continues to look at her doll. When the doctor asks her to look at a toy on his table by pointing a finger at the toy, she looks at neither his finger nor the toy. The doctor also notes that she keeps rocking her body while in the office. Which of the following is an epidemiological characteristic of the condition the girl is suffering from?
Q7
A 5-year-old non-verbal child with a history of autism is brought into the emergency department by his grandmother. The patient’s grandmother is concerned her grandchild is being abused at home. The patient lives in an apartment with his mother, step-father, and two older brothers in low-income housing. The department of social services has an open case regarding this patient and his family. The patient is afebrile. His vital signs include: blood pressure 97/62 mm Hg, pulse 175/min, respiratory rate 62/min. Physical examination reveals a malnourished and dehydrated child in dirty and foul-smelling clothes. Which one of the following people is most likely abusing this patient?
Q8
A 7-year-old girl is brought to the physician by her mother because she has been increasingly reluctant to speak at school over the past 4 months. Her teachers complain that she does not answer their questions and it is affecting her academic performance. She was born at 35 weeks' gestation and pregnancy was complicated by preeclampsia. Previous well-child examinations have been normal. Her older brother was diagnosed with a learning disability 4 years ago. She is at 65th percentile for height and weight. Physical examination shows no abnormalities. She follows commands. She avoids answering questions directly and whispers her answers to her mother instead who then mediates between the doctor and her daughter. Which of the following is the most likely diagnosis?
Q9
True about Fragile X syndrome is
Q10
Which of the following features is NOT typically associated with Fragile X syndrome?
Autism assessment tools US Medical PG Practice Questions and MCQs
Question 1: A mother brings her 3-year-old son to the doctor because she is worried that he might be harming himself by constantly banging his head on the wall. He has been exhibiting this behavior for a few months. She is also worried because he has started to speak less than he used to and does not respond when his name is called. He seems aloof during playtime with other children and seems to have lost interest in most of his toys. What is the most likely diagnosis?
A. Autism spectrum disorder (Correct Answer)
B. Attention deficit hyperactivity disorder
C. Generalized anxiety disorder
D. Bipolar disorder
E. Obsessive-compulsive disorder
Explanation: ***Autism spectrum disorder***
- The child's symptoms of **head banging** (a repetitive, self-stimulatory behavior), **decreased speech**, **lack of response to his name**, **social aloofness**, and **loss of interest in toys** are classic indicators of **Autism Spectrum Disorder (ASD)**.
- ASD involves persistent deficits in **social communication and interaction** across multiple contexts, as well as **restricted, repetitive patterns of behavior, interests, or activities**.
*Attention deficit hyperactivity disorder*
- **ADHD** is characterized primarily by **inattention, hyperactivity, and impulsivity**, which are not the prominent or primary concerns described in this case.
- While children with ADHD may have social difficulties, their core symptoms do not typically include severe **social aloofness, communication regression**, or **self-injurious repetitive behaviors** like head banging.
*Generalized anxiety disorder*
- **Generalized anxiety disorder (GAD)** in children typically presents with excessive worry about multiple events or activities, often accompanied by **physical symptoms of anxiety** such as restlessness, fatigue, and difficulty concentrating.
- It does not explain the **communication regression, social deficits**, or **stereotypical behaviors** like head banging observed in this child.
*Bipolar disorder*
- **Bipolar disorder** in children often manifests with severe mood dysregulation, including distinct periods of **elevated or irritable mood (mania/hypomania)** and depression.
- The symptoms described, such as social withdrawal and communication difficulties, are not characteristic of the primary presentations of bipolar disorder.
*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)**.
- While head banging can be a repetitive behavior, the broader constellation of symptoms, including social and communication deficits, is not typical of primary OCD in young children.
Question 2: A 4-year-old girl presents to the office with her parents who are concerned about their daughter and slow, progressive changes in her behavior. The girl was born at 39 weeks gestation via spontaneous vaginal delivery. She is up to date on all vaccines and was meeting all developmental milestones until about 2 years ago. At one point she had a vocabulary of several words and now she verbalizes in grunts. She also flaps her hands in a repeated motion and has difficulty walking. Her parents have tried several home therapies to improve their daughter's symptoms including restricted diets, hydrotherapy, and a variety of nutritional supplements. The vital signs include: heart rate 90/min, respiratory rate 22/min, blood pressure 110/65 mm Hg, and temperature 36.9°C (98.4°F). On physical exam, she is well nourished and stares absently out the window. Her heart has a regular rate and rhythm and her lungs are clear to auscultation bilaterally. She has mild scoliosis. Which of the following is the most likely diagnosis?
A. Autistic spectrum disorder
B. Tourette syndrome
C. Cerebral palsy
D. Phenylketonuria
E. Rett syndrome (Correct Answer)
Explanation: ***Rett syndrome***
- This presentation of a 4-year-old girl with previously met milestones, followed by **regression in language** (verbalizing in grunts), **loss of purposeful hand movements** (flapping hands), **gait abnormalities**, and **scoliosis**, is highly characteristic of Rett syndrome.
- Rett syndrome is a **neurodevelopmental disorder** found almost exclusively in girls caused by a mutation in the **MECP2 gene**, which typically manifests between 6 and 18 months of age with a period of normal development followed by regression.
*Autistic spectrum disorder*
- While autism involves **social and communication deficits** and **repetitive behaviors**, it typically presents earlier and does not usually involve a distinct period of **normal development followed by severe regression** in purposeful hand use and gait.
- The specific pattern of regression, especially the loss of purposeful hand movements, is more indicative of Rett syndrome than autism.
*Tourette syndrome*
- Tourette syndrome is characterized by **multiple motor tics** and **one or more vocal tics**, which can wax and wane.
- It does not typically involve the **profound developmental regression** in language, purposeful hand movements, and gait that this patient is experiencing.
*Cerebral palsy*
- Cerebral palsy is a group of **permanent movement disorders** that appear in early childhood, but it is caused by **non-progressive brain damage** or abnormal development, often prenatal or perinatal.
- It does not involve a period of **normal development followed by regression** of acquired skills, which is a hallmark feature in this case.
*Phenylketonuria*
- **Phenylketonuria (PKU)** is a metabolic disorder that can cause **intellectual disability**, seizures, and behavioral problems if untreated.
- However, it is usually screened for at birth, and prompt dietary intervention can prevent severe neurological damage; it does not typically present with the specific pattern of **developmental regression** seen here, particularly with respect to purposeful hand movements and gait.
Question 3: A 4-year-old boy is brought to the physician because of non-fluent speech. His mother worries that his vocabulary is limited for his age and because he cannot use simple sentences to communicate. She says he enjoys playing with his peers and parents, but he has always lagged behind in his speaking and communication. His speech is frequently not understood by strangers. He physically appears normal. His height and weight are within the normal range for his age. He responds to his name, makes eye contact, and enjoys the company of his mother. Which of the following is the most appropriate next step in management?
A. Referral to speech therapist
B. Evaluate response to methylphenidate
C. Psychiatric evaluation
D. Audiology testing (Correct Answer)
E. Thyroid-stimulating hormone
Explanation: ***Audiology testing***
- Before initiating any therapy for speech delay, it is crucial to rule out **hearing impairment**, as **undiagnosed hearing loss** is the most common organic cause of speech and language difficulties in children.
- **Standard practice guidelines** (AAP) recommend hearing assessment as the **first diagnostic step** in evaluating any child with speech or language delay.
- While other developmental aspects seem intact, the inability to use simple sentences at age 4 and speech that is "frequently not understood by strangers" strongly suggests the need to assess the child's ability to **receive auditory information**.
*Referral to speech therapist*
- While a **speech therapist referral** is highly appropriate for a child with significant speech delay, it should typically follow an assessment to rule out underlying organic causes like **hearing loss**.
- Without addressing potential hearing impairment, speech therapy may be less effective or miss the root cause of the communication difficulty.
*Evaluate response to methylphenidate*
- **Methylphenidate** is a stimulant medication used primarily for **attention-deficit/hyperactivity disorder (ADHD)**.
- There is no indication of ADHD symptoms in this child (e.g., inattention, hyperactivity, impulsivity), and it is not a treatment for **primary speech delay**.
*Psychiatric evaluation*
- The child's ability to respond to his name, make eye contact, and enjoy social interaction with family and peers makes a **primary psychiatric disorder** (like autism spectrum disorder) less likely to be the sole cause of the speech delay.
- Such an evaluation would typically be considered if **social communication deficits**, repetitive behaviors, or restricted interests were prominent.
*Thyroid-stimulating hormone*
- **Hypothyroidism** can cause developmental delays, including speech delay.
- However, the child's normal physical appearance, height, and weight make **congenital or acquired hypothyroidism** less likely to be the primary cause of his isolated speech delay.
Question 4: A 3-year-old boy is brought in by his mother because she is concerned that he has been “acting differently recently”. She says he no longer seems interested in playing with his friends from preschool, and she has noticed that he has stopped making eye contact with others. In addition, she says he flaps his hands when excited or angry and only seems to enjoy playing with objects that he can place in rows or rigid patterns. Despite these behaviors, he is meeting his language goals for his age (single word use). The patient has no significant past medical history. He is at the 90th percentile for height and weight for his age. He is afebrile and his vital signs are within normal limits. A physical examination is unremarkable. Which of the following is the most likely diagnosis in this patient?
A. Pervasive developmental disorder, not otherwise specified
B. Autism spectrum disorder (Correct Answer)
C. Rett’s disorder
D. Childhood disintegrative disorder
E. Asperger’s disorder
Explanation: ***Autism spectrum disorder***
- This patient exhibits **persistent deficits in social communication and social interaction** (e.g., lack of interest in friends, poor eye contact) and **restricted, repetitive patterns of behavior, interests, or activities** (e.g., hand flapping, lining up objects). These are the core diagnostic criteria for **autism spectrum disorder (ASD)**.
- The symptoms are presenting in **early childhood** (age 3) and are causing **clinically significant impairment** in social, occupational, or other important areas of current functioning, consistent with an ASD diagnosis.
*Pervasive developmental disorder, not otherwise specified*
- This diagnosis was previously used when a child met some, but not all, criteria for autistic disorder or when there was atypical presentation. However, under **DSM-5**, these conditions are now unified under the single diagnosis of **Autism Spectrum Disorder**.
- Its usage has been largely superseded by the broader diagnosis of **Autism Spectrum Disorder** in the DSM-5.
*Rett’s disorder*
- **Rett's disorder** primarily affects **females** and is characterized by a period of normal development followed by a loss of acquired hand skills, severe intellectual disability, and characteristic hand-wringing movements. This patient is a male and does not exhibit these specific features.
- Patients typically experience **regression** in language and motor skills after normal early development, which is not described in this case, and they develop **microcephaly**.
*Childhood disintegrative disorder*
- This diagnosis involves a **marked regression** in multiple areas of functioning (social, communication, motor) after at least **2 years of normal development**.
- The patient's mother notes recent changes, but there is no indication of previous normal development followed by significant loss of skills across multiple domains after age 2, which differentiates it from the insidious onset of ASD symptoms.
*Asperger’s disorder*
- **Asperger’s disorder** was characterized by **significant difficulties in social interaction** and **restricted, repetitive patterns of behavior**, but with **no clinically significant delay in language or cognitive development**.
- In **DSM-5**, Asperger's disorder is no longer a distinct diagnosis and is now subsumed under the umbrella of **Autism Spectrum Disorder**, which better reflects the spectrum of symptom severity.
Question 5: A 4-year-old girl is brought to the physician because her mother is concerned that she has been talking to an imaginary friend for 2 months. The child calls her friend 'Lucy' and says “Lucy is my best friend”. The child has multiple conversation and plays with the 'Lucy' throughout the day. The girl attends preschool regularly. She can copy a circle, tells stories, and can hop on one foot. Her maternal uncle has schizophrenia. Her parents are currently divorcing. The child's father has a history of illicit drug use. Physical examination shows no abnormalities. The mother is concerned about whether the child is acting out because of the divorce. Which of the following is the most appropriate next best step in management?
A. Reassure the mother (Correct Answer)
B. Perform MRI of the brain
C. Schedule psychiatry consult
D. Inform Child Protective Services
E. Screen urine for drugs
Explanation: ***Reassure the mother***
- Imaginary friends are a **normal developmental phenomenon** in preschool-aged children, often associated with creativity and good social skills.
- The child's developmental milestones (copying a circle, hopping, telling stories) are appropriate for her age, indicating **healthy cognitive and motor development**.
*Perform MRI of the brain*
- There are **no neurological symptoms** or concerning signs in this case that would warrant an MRI of the brain.
- Imaginary friends are not indicative of a brain abnormality or neurological disorder.
*Schedule psychiatry consult*
- A psychiatry consult is **not indicated** as the child's behavior is developmentally appropriate.
- While there is a family history of schizophrenia and parental stress, the child is exhibiting typical childhood play and not symptoms of a mental health disorder.
*Inform Child Protective Services*
- There is **no evidence of child abuse or neglect** in the provided information.
- Although the parents are divorcing and the father has a history of drug use, there are no specific concerns raised about the child's safety or well-being that would require CPS involvement.
*Screen urine for drugs*
- A drug screen is **not relevant** to the child's behavior or a concern for drug use by the child.
- While the father has a history of illicit drug use, this does not automatically imply the child is being exposed to drugs, and the child's symptoms are unrelated to drug exposure.
Question 6: A 4-year-old girl is brought to the pediatrician by her parents after her mother recently noticed that other girls of similar age talk much more than her daughter. Her mother reports that her language development has been abnormal and she was able to use only 5–6 words at the age of 2 years. Detailed history reveals that she has never used her index finger to indicate her interest in something. She does not enjoy going to birthday parties and does not play with other children in her neighborhood. The mother reports that her favorite “game” is to repetitively flex and extend the neck of a doll, which she always keeps with her. She is sensitive to loud sounds and starts screaming excessively when exposed to them. There is no history of delayed motor development, seizures, or any other major illness; perinatal history is normal. When she enters the doctor’s office, the doctor observes that she does not look at him. When he gently calls her by her name, she does not respond to him and continues to look at her doll. When the doctor asks her to look at a toy on his table by pointing a finger at the toy, she looks at neither his finger nor the toy. The doctor also notes that she keeps rocking her body while in the office. Which of the following is an epidemiological characteristic of the condition the girl is suffering from?
A. There has been a steady decline in prevalence in the United States over the last decade.
B. There is an increased risk if the mother smoked during pregnancy.
C. There is an increased risk with low prenatal maternal serum vitamin D level.
D. There is an increased incidence if the mother gives birth before 25 years of age.
E. This condition is 4 times more common in boys than girls. (Correct Answer)
Explanation: **_This condition is 4 times more common in boys than girls._**
- The clinical presentation, including **impaired social interaction** (not looking at the doctor, not responding to her name, not playing with other children, not enjoying parties), **communication deficits** (delayed language, lack of pointing), **repetitive behaviors** (flexing doll's neck, body rocking) and **sensory sensitivities** (screaming at loud sounds), is highly suggestive of **Autism Spectrum Disorder (ASD)**.
- **ASD** is indeed diagnosed approximately four times more often in boys than in girls, making this a characteristic epidemiological feature.
*There has been a steady decline in prevalence in the United States over the last decade.*
- The **prevalence of ASD** has actually been **steadily increasing** in the United States and globally over the last few decades, partly due to increased awareness, improved diagnostic criteria, and better screening.
- This statement is contrary to current epidemiological trends for **ASD**.
*There is an increased risk if the mother smoked during pregnancy.*
- While maternal smoking during pregnancy is linked to other developmental issues like **ADHD** and **premature birth**, a definitive, strong, and consistent causal link to a significantly increased risk of **ASD** has not been established.
- Research on environmental risk factors for **ASD** is ongoing, but maternal smoking is not a primary, well-established epidemiological characteristic.
*There is an increased risk with low prenatal maternal serum vitamin D level.*
- Some studies suggest a potential association between low prenatal maternal vitamin D levels and an increased risk of **ASD**, but this link is **not yet definitively established** and requires further research to confirm causation.
- It is considered a potential risk factor, but not a widely accepted or strong epidemiological characteristic for the condition.
*There is an increased incidence if the mother gives birth before 25 years of age.*
- The risk of **ASD** has been more consistently associated with **advanced parental age** (both maternal and paternal), not with younger maternal age.
- Studies generally indicate a **higher risk for children born to older parents**, making this statement inaccurate.
Question 7: A 5-year-old non-verbal child with a history of autism is brought into the emergency department by his grandmother. The patient’s grandmother is concerned her grandchild is being abused at home. The patient lives in an apartment with his mother, step-father, and two older brothers in low-income housing. The department of social services has an open case regarding this patient and his family. The patient is afebrile. His vital signs include: blood pressure 97/62 mm Hg, pulse 175/min, respiratory rate 62/min. Physical examination reveals a malnourished and dehydrated child in dirty and foul-smelling clothes. Which one of the following people is most likely abusing this patient?
A. Mother (Correct Answer)
B. Neighbor
C. Brother
D. Stranger
E. Step-father
Explanation: ***Mother***
- **Child abuse** is complex, but the **mother (or primary caregiver)** is often the abuser, especially in cases where the child is non-verbal and has a disability.
- The child's **malnutrition and poor hygiene** point to neglect, which is a form of abuse, and the primary caregiver is responsible for the child's basic needs.
*Neighbor*
- While abuse can occur outside the home, a **neighbor is highly unlikely** to be responsible for the child's chronic neglect, malnutrition, and dehydration, given the living circumstances described.
- **Neighbors typically do not have consistent, unsupervised access** to a child in a manner that would lead to such severe and ongoing neglect.
*Brother*
- Although **siblings can be perpetrators of abuse**, particularly physical or sexual abuse, it is **uncommon for siblings to be responsible for severe neglect** leading to malnutrition and chronic poor hygiene in a younger child.
- This kind of chronic neglect usually points to a **primary caregiver's failure** to provide basic needs.
*Stranger*
- Abuse by a **stranger is relatively rare** compared to abuse by a family member or acquaintance.
- The consistent pattern of **neglect, malnutrition, and poor hygiene** suggests ongoing failure of care within the home environment, not a single or intermittent encounter with a stranger.
*Step-father*
- A **step-father is a recognized risk factor for child abuse**, and he could certainly be involved, especially given the child's vulnerability.
- However, in cases of **chronic neglect and failure to provide basic care**, the primary responsibility often lies with the **biological parent** who is also a co-resident caregiver.
Question 8: A 7-year-old girl is brought to the physician by her mother because she has been increasingly reluctant to speak at school over the past 4 months. Her teachers complain that she does not answer their questions and it is affecting her academic performance. She was born at 35 weeks' gestation and pregnancy was complicated by preeclampsia. Previous well-child examinations have been normal. Her older brother was diagnosed with a learning disability 4 years ago. She is at 65th percentile for height and weight. Physical examination shows no abnormalities. She follows commands. She avoids answering questions directly and whispers her answers to her mother instead who then mediates between the doctor and her daughter. Which of the following is the most likely diagnosis?
A. Selective mutism (Correct Answer)
B. Social anxiety disorder
C. Rett syndrome
D. Autism spectrum disorder
E. Reactive attachment disorder
Explanation: ***Selective mutism***
- The child's reluctance to speak in specific social situations (school) despite being able to speak in others (whispering to her mother), and the impact on academic performance, are classic signs of **selective mutism**
- **Selective mutism** typically involves anxiety and a consistent failure to speak in situations where speaking is expected, despite speaking in other situations
- This diagnosis fits the **DSM-5 criteria**: consistent failure to speak in specific social situations for >1 month, interfering with educational achievement
*Social anxiety disorder*
- While social anxiety can be **comorbid** with selective mutism, the hallmark of this presentation is the **specific refusal to speak** in certain settings, rather than generalized anxiety about social interactions
- A child with generalized social anxiety might interact nervously but would likely attempt to speak, which is not described here
*Rett syndrome*
- **Rett syndrome** is a neurodevelopmental disorder almost exclusively affecting girls, characterized by **normal early development followed by regression** of acquired skills, loss of purposeful hand use, and deceleration of head growth
- The presented symptoms of reluctance to speak in specific settings, without other regressive signs or developmental abnormalities, do not fit the diagnosis of Rett syndrome
*Autism spectrum disorder*
- **Autism spectrum disorder** is characterized by persistent deficits in **social communication and social interaction** across multiple contexts, and **restricted, repetitive patterns of behavior**
- This child's ability to speak to her mother and follow commands suggests intact communication skills in some contexts, making autism less likely than selective mutism for the primary presentation
*Reactive attachment disorder*
- **Reactive attachment disorder** typically arises from patterns of **extremely insufficient care** in early childhood, leading to emotionally withdrawn behavior toward caregivers and limited positive affect
- The child's selective non-speaking in school in this scenario, with normal previous well-child examinations and interaction with her mother, is inconsistent with the characteristic features of reactive attachment disorder
Question 9: True about Fragile X syndrome is
A. 10% Female carriers mentally retarded
B. Males have IQ 20-40 (Correct Answer)
C. Triple nucleotide CAG Sequence mutation
D. Gain of function mutation
E. Autosomal dominant inheritance pattern
Explanation: ***Males have IQ 20-40***
- **Fragile X syndrome** is a significant cause of inherited intellectual disability, and affected males typically present with moderate to severe intellectual impairment, corresponding to an **IQ range of 20-60**, with many in the **20-40 range**.
- This intellectual deficit is a hallmark of the syndrome in males due to the nearly complete loss of **FMRP protein**.
*10% Female carriers mentally retarded*
- While some **female carriers** of Fragile X syndrome may experience mild intellectual deficits or learning challenges, the proportion is significantly higher than 10%, with estimates often around **30-50%** showing some intellectual or significant learning disability.
- Many female carriers are cognitively normal, but those affected typically demonstrate **milder symptoms** than males.
*Triple nucleotide CAG Sequence mutation*
- Fragile X syndrome is caused by an expansion of a **CGG triplet repeat** in the *FMR1* gene, not CAG.
- The expansion of **CGG repeats** (>200 repeats in full mutation) leads to hypermethylation and silencing of the *FMR1* gene, reducing or eliminating the production of **Fragile X Mental Retardation Protein (FMRP)**.
*Gain of function mutation*
- Fragile X syndrome is caused by a **loss-of-function mutation** due to the silencing of the *FMR1* gene.
- The lack of **FMRP** (Fragile X Mental Retardation Protein) leads to synaptic dysfunction and the characteristic features of the syndrome.
*Autosomal dominant inheritance pattern*
- Fragile X syndrome follows an **X-linked dominant** inheritance pattern, not autosomal dominant.
- Males are more severely affected because they have only one X chromosome, while females have two X chromosomes and often show milder symptoms due to X-inactivation and mosaicism.
Question 10: Which of the following features is NOT typically associated with Fragile X syndrome?
A. Enlarged testes
B. Prominent facial features
C. Small ears (Correct Answer)
D. Intellectual disability
E. Microcephaly
Explanation: ***Small ears***
- **Small ears** are not a typical feature of Fragile X syndrome; individuals often have **large, prominent ears**.
- This question asks for the feature *not* typically associated with the syndrome.
*Intellectual disability*
- **Intellectual disability**, particularly in males, is the most common and defining feature of Fragile X syndrome.
- It usually ranges from **mild to severe**, affecting cognitive function and adaptive skills.
*Enlarged testes*
- **Macroorchidism** (enlarged testes) is a characteristic physical finding in postpubertal males with Fragile X syndrome.
- This symptom becomes apparent after puberty and is an important diagnostic clue.
*Prominent facial features*
- **Prominent facial features** are typical, including a **long face**, **prominent jaw (prognathism)**, and **large, prominent ears**.
- These features become more noticeable with age.
*Microcephaly*
- **Microcephaly** (abnormally small head) is not typically associated with Fragile X syndrome.
- Individuals with Fragile X generally have **normal or slightly increased head circumference**, not microcephaly.
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