Question 1: Risk of genetic diseases in consanguineous marriage between first cousins?
- A. 1-2%
- B. 4-8% (Correct Answer)
- C. 8-10%
- D. 12-14%
- E. 2-4%
Explanation: ***4-8%***
- The risk of genetic diseases in offspring from a **first-cousin consanguineous marriage** is generally estimated to be **two- to threefold higher than the baseline risk** in the general population.
- While the general population risk for a serious birth defect or genetic disease is around 3-4%, this increased risk typically places the range for first cousins at **4-8%**.
*1-2%*
- This percentage represents a **lower risk than what is typically observed** with first-cousin consanguinity.
- The baseline risk for genetic disease in the general population is usually around 3-4%, and consanguineous unions significantly increase this risk.
*2-4%*
- This represents approximately the **baseline population risk** without consanguinity, not the increased risk seen with first-cousin marriages.
- Students may incorrectly assume that first-cousin marriage does not significantly elevate the baseline genetic disease risk.
*8-10%*
- While there is an increased risk, this range is generally considered **higher than the average estimated risk** for first-cousin consanguineous marriages, which is typically quoted at 4-8%.
- This higher range might be seen in cases of **more distant consanguinity** or in populations with a **higher prevalence of specific recessive conditions**.
*12-14%*
- This magnitude of risk is usually associated with **closer degrees of consanguinity**, such as uncle-niece or half-sibling relationships, rather than first cousins.
- The **coefficient of inbreeding** for first cousins is 1/16, which carries a lower risk than these closer relationships.
Question 2: What is the typical IQ range for males affected with Fragile X syndrome?
- A. IQ range of 20-40
- B. IQ range of 60-80 (Correct Answer)
- C. IQ range of 80-100
- D. Normal IQ range (90-110)
- E. IQ range of 50-70
Explanation: **IQ range of 60-80**
- Males affected with **Fragile X syndrome** typically experience **moderate intellectual disability**, corresponding to an IQ range of 60-80.
- This range indicates significant cognitive impairment, yet usually allows for some level of independent living and vocational skills with support.
*IQ range of 20-40*
- An IQ range of 20-40 represents **severe intellectual disability**, which is less common for the typical presentation of Fragile X syndrome in males.
- While some individuals with Fragile X may fall into this range, it is not considered the most typical or average outcome.
*IQ range of 50-70*
- An IQ range of 50-70 represents **mild to moderate intellectual disability**, which overlaps with but is generally slightly lower than the most typical presentation.
- While many males with Fragile X syndrome may score in this range, the typical range cited in literature extends slightly higher to 60-80.
*IQ range of 80-100*
- An IQ range of 80-100 is considered **borderline to low-average intelligence**, which is generally higher than the typical impact of Fragile X syndrome on male cognitive function.
- This range is not indicative of the moderate intellectual disability characteristic of the syndrome.
*Normal IQ range (90-110)*
- A **normal IQ range (90-110)** is inconsistent with the diagnosis of Fragile X syndrome, which is a leading cause of inherited intellectual disability.
- While females with Fragile X may have a wider range of IQs, including normal intelligence, males are typically more severely affected.