Carnevale et al. (1976) described a brother and sister with congenital absence of gluteal muscles and with spina bifida occulta. They posited that the sibs were homozygous for a gene that, in heterozygous form in both parents and ... Carnevale et al. (1976) described a brother and sister with congenital absence of gluteal muscles and with spina bifida occulta. They posited that the sibs were homozygous for a gene that, in heterozygous form in both parents and 2 apparently normal sibs, was expressed as sacral spina bifida occulta. Two other sibs had died soon after birth, one with anencephaly and the other with probable spina bifida. Edgar et al. (2012) reported the case of a 15-year-old white male with congenital absence of the gluteus maximus muscles associated with spina bifida occulta, learning disability, optic nerve hypoplasia, scoliosis, and central nervous system hamartomas.