Autosomal recessive inheritance of the mutant allele from a distant relative common to both parents of the proband.

(A) SSCP analysis demonstrates that genomic DNA from NHBM is homozygous for the wild-type allele, EE; the patient is homozygous for the mutant allele containing the A-nucleotide insertion, ee; and both parents are heterozygous, Ee. (B) Microsatellite analysis reveals that the mutant, e, but not the wild-type, E, alleles carried by the parents possesses the same “fingerprint,” indicating they inherited the mutant allele from the same distant relative.