Question

A Tibetan individual who is heterozygous for the DISC1 and EPAS1 loci mates and produces offspring with someone from

the Han population. If the Chinese individual is heterozygous at the EPASI and homozygous at the DISC1 locus, what are the genotypic ratios you'd expect in their offspring?
1.) 3:1
2.) 1:1:1:1:2:2
3.) Based on the data, there are not heterozygous individuals from Tibet or EPAS 1.
4.) 9:3:3:1
5.) All dominant.

Answer 1

The expected genotypic ratio for offspring from a Tibetan individual heterozygous at DISC1 and EPAS1 loci mating with a Han individual heterozygous at EPAS1 and homozygous at DISC1 loci would be 1:1:1:1, assuming independent assortment and no linkage between the loci.

Step-by-step explanation:

When a Tibetan individual who is heterozygous for the DISC1 and EPAS1 loci mates with someone from the Han population who is heterozygous at the EPAS1 and homozygous at the DISC1 locus, we expect a certain genotypic ratio of their offspring. To solve this, we need to use a Punnett square for each gene separately since no linkage is stated.

For the DISC1 loci, since one parent is heterozygous (Dd) and the other is homozygous (DD or dd), the offspring would have a genotypic ratio of 1:1 (Dd:DD or Dd:dd, depending on the homozygous condition of the Han individual). For the EPAS1, both are heterozygous (Ee), which typically gives a genotypic ratio of 1:2:1 (EE:Ee:ee).

When combining these two loci, we multiply the ratios to find the expected genotypic ratio for the offspring. This gives a final genotypic ratio of 1:1:1:1 when is considered both homozygous dominant or recessive and heterozygous possibilities for each locus, resulting in four possible genotype combinations equally likely.