DR Medhat MRCP

Criteria
Autosomal dominant Autosomal recessive
Results from mutation of 1 copy (allele) of the
autosomal gene
Both homozygotes and heterozygotes manifest
disease (THERE IS NO CARRIER STATE).
Both males and females affected
Only affected individuals can pass on disease.
Disease is passed on to 50% of children i.e all
offsprings of an affected person have 50%
chance of inherting the mutation.
Normally appears in every generation (although
see below).
Risk remains same for each successive pregnancy
Only homozygotes are affected
Males and females are equally likely to be affected
Does not manifest in every generation - may 'skip a
generation'
- 25 % homozygote - 100% carrier (heterozygote)
- 50% Heterozygote
- 25 % Normal.