NEET-PG 2015 — Psychiatry

Q: All of the following are true about Down syndrome except for one.

Incidence of Robertsonian translocation is 1:1000. **Incidence of Robertsonian translocation is 1:1000** - This statement is **not accurate** for Down syndrome. Robertsonian translocation accounts for only about **3-4% of Down syndrome cases**, not a general population incidence of 1:1000. - The vast majority of Down syndrome cases (~95%) are due to trisomy 21 from nondisjunction, not translocation. - This is the **correct answer** as it is the FALSE statement. *Extra chromosome is of maternal origin* - In approximately **90-95% of Down syndrome cases**, the extra copy of chromosome 21 originates from the mother due to **nondisjunction** during meiosis. - This maternal origin is strongly correlated with **advanced maternal age**. *Most common cause is trisomy 21* - **Trisomy 21** (due to meiotic nondisjunction) accounts for about **95% of all Down syndrome cases**, making it the most common genetic mechanism. - This results in three separate copies of chromosome 21 in all body cells. *Mosaicism 21 has no association with maternal age* - **Mosaic Down syndrome** occurs when nondisjunction happens *after fertilization* in early embryonic development, leading to a mixture of cells with normal and trisomic cells. - Because it is a **post-zygotic event**, its incidence is independent of **maternal age**, unlike full trisomy 21. *Incidence increases with advanced maternal age* - **TRUE statement** - The risk of Down syndrome (particularly trisomy 21) increases significantly with **maternal age**. - Risk is approximately 1:1500 at age 20, 1:1000 at age 30, 1:400 at age 35, and 1:100 at age 40. - This is due to increased risk of meiotic nondisjunction in older oocytes. [Practice more Psychiatry PYQs on OnCourse]

Q: Which of the following is NOT a feature of CHARGE syndrome?

Esophageal Atresia. ***Esophageal Atresia*** - While other **tracheoesophageal abnormalities** can occur in CHARGE syndrome, **esophageal atresia** is not typically considered one of the core diagnostic criteria. - The acronym CHARGE stands for a specific set of features, and esophageal atresia is not directly included, unlike **choanal atresia**. *Eye Coloboma* - **Coloboma** of the eye, particularly the iris or retina, is a **major diagnostic feature** of CHARGE syndrome. - This congenital malformation results from incomplete closure of the **choroid fissure** during development. *Congenital heart disease* - Various types of **congenital heart defects**, such as **tetralogy of Fallot** or an **atresia of the aortic valve**, are common in CHARGE syndrome. - These cardiac anomalies are a **major diagnostic criterion** and significantly impact patient management. *Choanal Atresia* - **Choanal atresia** represents the "A" in the CHARGE acronym and is a **major diagnostic criterion**. - This condition involves blockage of the nasal passages and is one of the most characteristic features of the syndrome. *Urinary tract defects* - **Genital and urinary abnormalities** are frequently observed in individuals with CHARGE syndrome. - These can include **hypoplastic genitalia** and **kidney abnormalities**, classifying as a **minor diagnostic feature**. [Practice more Psychiatry PYQs on OnCourse]

2 Previous Year Questions with Answers & Explanations

Questions

All of the following are true about Down syndrome except for one.

Which of the following is NOT a feature of CHARGE syndrome?

NEET-PG 2015 - Psychiatry NEET-PG Practice Questions and MCQs

Question 1: All of the following are true about Down syndrome except for one.

A. Incidence of Robertsonian translocation is 1:1000 (Correct Answer)
B. Most common cause is trisomy 21
C. Mosaicism 21 has no association with maternal age
D. Extra chromosome is of maternal origin
E. Incidence increases with advanced maternal age

Explanation: **Incidence of Robertsonian translocation is 1:1000** - This statement is **not accurate** for Down syndrome. Robertsonian translocation accounts for only about **3-4% of Down syndrome cases**, not a general population incidence of 1:1000. - The vast majority of Down syndrome cases (~95%) are due to trisomy 21 from nondisjunction, not translocation. - This is the **correct answer** as it is the FALSE statement. *Extra chromosome is of maternal origin* - In approximately **90-95% of Down syndrome cases**, the extra copy of chromosome 21 originates from the mother due to **nondisjunction** during meiosis. - This maternal origin is strongly correlated with **advanced maternal age**. *Most common cause is trisomy 21* - **Trisomy 21** (due to meiotic nondisjunction) accounts for about **95% of all Down syndrome cases**, making it the most common genetic mechanism. - This results in three separate copies of chromosome 21 in all body cells. *Mosaicism 21 has no association with maternal age* - **Mosaic Down syndrome** occurs when nondisjunction happens *after fertilization* in early embryonic development, leading to a mixture of cells with normal and trisomic cells. - Because it is a **post-zygotic event**, its incidence is independent of **maternal age**, unlike full trisomy 21. *Incidence increases with advanced maternal age* - **TRUE statement** - The risk of Down syndrome (particularly trisomy 21) increases significantly with **maternal age**. - Risk is approximately 1:1500 at age 20, 1:1000 at age 30, 1:400 at age 35, and 1:100 at age 40. - This is due to increased risk of meiotic nondisjunction in older oocytes.

Question 2: Which of the following is NOT a feature of CHARGE syndrome?

A. Esophageal Atresia (Correct Answer)
B. Congenital heart disease
C. Urinary tract defects
D. Eye Coloboma
E. Choanal Atresia

Explanation: ***Esophageal Atresia*** - While other **tracheoesophageal abnormalities** can occur in CHARGE syndrome, **esophageal atresia** is not typically considered one of the core diagnostic criteria. - The acronym CHARGE stands for a specific set of features, and esophageal atresia is not directly included, unlike **choanal atresia**. *Eye Coloboma* - **Coloboma** of the eye, particularly the iris or retina, is a **major diagnostic feature** of CHARGE syndrome. - This congenital malformation results from incomplete closure of the **choroid fissure** during development. *Congenital heart disease* - Various types of **congenital heart defects**, such as **tetralogy of Fallot** or an **atresia of the aortic valve**, are common in CHARGE syndrome. - These cardiac anomalies are a **major diagnostic criterion** and significantly impact patient management. *Choanal Atresia* - **Choanal atresia** represents the "A" in the CHARGE acronym and is a **major diagnostic criterion**. - This condition involves blockage of the nasal passages and is one of the most characteristic features of the syndrome. *Urinary tract defects* - **Genital and urinary abnormalities** are frequently observed in individuals with CHARGE syndrome. - These can include **hypoplastic genitalia** and **kidney abnormalities**, classifying as a **minor diagnostic feature**.