What is the expected prevalence of heterozygous females for Lesch-Nyhan syndrome, given its occurrence in 1 in 100,000 males?

What is the expected prevalence of heterozygous females for Lesch-Nyhan syndrome, given its occurrence in 1 in 100,000 males?

• A. 1 in 10,000
• B. 1 in 50,000
• C. 1 in 1000
• D. 1 in 200,000

Answer: (B)

Lesch-Nyhan syndrome is an X-linked recessive disorder, which means it primarily affects males who have only one X chromosome. Females have two X chromosomes and thus require mutations in both copies of the gene to express the disorder, making the condition much rarer in females. The prevalence of the syndrome in males is given as 1 in 100,000. Since males are affected directly by the mutation of the gene on the X chromosome, we can calculate the expected prevalence of heterozygous females (carriers) based on the population dynamics of X-linked traits. In a large population, if 1 in 100,000 males are affected, there will be approximately twice as many female carriers as affected males, due to the nature of X-linked inheritance. The carrier frequency is typically estimated as twice the affected male prevalence divided by the frequency of male births (which is approximately equal to the number of females). Therefore, if the affected prevalence is 1 in 100,000, the expected prevalence of carrier females (heterozygous) would be roughly 2 in 100,000, translating to 1 in 50,000. This estimation aligns with the expected carrier frequency for X-linked recessive conditions,

Lesch-Nyhan syndrome is an X-linked recessive disorder, which means it primarily affects males who have only one X chromosome. Females have two X chromosomes and thus require mutations in both copies of the gene to express the disorder, making the condition much rarer in females.

The prevalence of the syndrome in males is given as 1 in 100,000. Since males are affected directly by the mutation of the gene on the X chromosome, we can calculate the expected prevalence of heterozygous females (carriers) based on the population dynamics of X-linked traits.

In a large population, if 1 in 100,000 males are affected, there will be approximately twice as many female carriers as affected males, due to the nature of X-linked inheritance. The carrier frequency is typically estimated as twice the affected male prevalence divided by the frequency of male births (which is approximately equal to the number of females). Therefore, if the affected prevalence is 1 in 100,000, the expected prevalence of carrier females (heterozygous) would be roughly 2 in 100,000, translating to 1 in 50,000.

This estimation aligns with the expected carrier frequency for X-linked recessive conditions,