Figure 1.

(A) Family tree of three generations in a non-consanguineous Scottish kinship with CYP11A1 deficiency affecting three brothers. The father carries a disruptive variant (c.790_802del, K264Lfs*5), while the mother is a carrier for a relatively common variant (c.940G>A, p.Glu314Lys) which was previously predicted as benign but which has been found to affect splicing. All brothers are compound heterozygotes, one sister is a carrier for c.790_802del mutation and the other is unaffected. None of the third generation has been tested. (B) X-linkage studies in a kinship with primary adrenal insufficiency indicating that the three affected brothers had inherited the same maternal X chromosome, suggesting an X-linked disorder. Subsequently, the brothers were found to be compound heterozygotes for CYP11A1 deficiency, inherited in autosomal recessive fashion. (C) Chromatogram showing paternally inherited c.790_802del, K264Lfs*5 and maternally inherited c.940G>A, p.Glu314Lys changes in CYP11A1, resulting in P450 side-chain cleavage enzyme deficiency.