1. Testing an Aa × aa pedigree against a 1:1 ratio
Genetics studentBackground
A pedigree shows one affected heterozygous parent, one unaffected parent, eight affected children, and seven unaffected children.
Problem
Determine the expected offspring risk and whether the observed counts fit autosomal dominant inheritance.
How to use
Select affected heterozygous (Aa) for Parent 1 and unaffected (aa) for Parent 2. Enter 8 affected children and 7 unaffected children, then mark male-to-male transmission as observed.
Parent 1: Aa; Parent 2: aa; affected: 8; unaffected: 7; male-to-male transmission: yes; decimal places: 4.Outcome
The analyzer reports a 1:1 expected ratio, 50% per-child risk, and chi-square = 0.0667, indicating that the observed 8:7 counts fit the expectation. Father-to-son transmission is consistent with autosomal dominant inheritance.