About today's discussion related to the patient affected by microcephaly described in the paper by Lancaster et al., 2013 - I confirm you that it's an autosomal recessive genetic disorder that is characterized for this patient by compound heterozygosity. Each "unaffected" parent was heterozygous for 1 of the mutations - the patient inherited from each parent a non sense mutation at different location - the result is that the patient has two recessive alleles (but mutated at different sites) for the CDK5RAP2 gene and develop the disease.