The risk of siblings being affected depends on the mode of inheritance and the gender of the affected parent (in X-linked disease). The risk of siblings being affected depends on the mode of inheritance and the gender of the affected parent (in X-linked disease). Examples of families of females (arrows) who have inherited X-linked Alport syndrome from their father (A) or mother (B), indicating other family members who are likely to be affected. All the daughters of the affected father are affected, and half the sons and daughters of the affected mother. (C) Indicates the family of a woman with autosomal recessive disease. With autosomal recessive disease, males and females (with two COL4A3 or COL4A4 mutations) are affected equally often and equally severely, and disease occurs in only one generation. Other family members with only one mutation (half-shaded symbols) have thin basement membrane nephropathy and are much less likely to develop renal failure than females with X-linked Alport syndrome. Judy Savige et al. CJASN 2016;11:1713-1720 ©2016 by American Society of Nephrology