Inheritance for the following pedigree !

Any shaded circle or square means the individual is affected. This is unlikely to be a dominant disease because it skips generations. So we can assume it is recessive. Therefore, I-2 and IV-22 are most likely bb. It is unlikely that the condition is X-linked because both males and females are affected and anyway two females and only one male are affected. Usually x-linked traits would unequally affect males. II-4 must be Bb (instead of BB) because mom is homozygous recessive (bb). Therefore, II-4 must have at least one recessive allele. So, to summarize:

I-2: bb
IV-22: bb
II-4: Bb

Post Merge: 9 years ago

Also I forgot to say: Mode of inheritance will be autosomal recessive