Feature of Autosomal dominant disorder:
Autosomal dominant disorder usually have late onset of disease due to presence of one non mutated gene which can function normally. In contrast with autosomal recessive where onset is early due to presence of mutation in both gene present. Complete penetrance is feature of autosomal recessive disorder, as individual who inherits the both mutated gene, individual will have symptom. As in autosomal dominant disorder, some individual shows mild, some might have moderate or some severe. Some individual might not express the phenotype even though they inherit the allele. Therefore incomplete penetrance is feature of AD disorder. Male to male transmission is possible in autosomal inheritance condition. In autosomal dominant condition like achondroplasia: Normally, FGF-mediated activation of FGFR3 inhibits endochondral growth. Constitutive activation of FGFR3 exaggerates this effect, suppressing growth. Approximately 90% of cases stem from new mutations, almost all of which occur in the paternal allele.
Present early in life
Complete penetrance common
New germ cell mutations in old fathers
Male to male transmission not possible
JIPMER 2017