Although individual III-2 doesn't display any disease traits, having an affected child indicates a 100% probability that III-2 is a heterozygous carrier.
How to analyze the chart
In this provided pedigree chart, let's initially examine the nature of the disorder. It doesn't align with either X-linked dominant or autosomal dominant traits due to the occurrence of generation skipping.
The presence of the trait in individual IV-6 while their father shows no signs rules out an X-linked recessive condition. Hence, it's evident that this case involves an autosomal recessive disorder.
For an autosomal recessive disorder, three scenarios may occur:
Firstly, if both parents are affected (homozygous recessive), all offspring will exhibit the disease, as observed in the children of IV-5 and IV-6.
Secondly, if one parent is affected (homozygous recessive) and the other is a carrier (heterozygous), there's a 50% likelihood of having an affected child.
Lastly, if both parents are carriers (heterozygous), there's a 25% chance of their child being affected.
Although individual III-2 doesn't display any disease traits, having an affected child indicates a 100% probability that III-2 is a heterozygous carrier.