meckel-gruber syndrome

description

this multiple congenital abnormalities syndrome was first described by meckel in 1822 and reviewed by gruber in 1934. the classic triad includes renal cystic dysplasia (100%), central nervous system anomalies – most commonly an occipital encephalocele – (60% to 85%), and postaxial polydactyly (55%). other brain abnormalities include occipital encephalocoele, microcephaly, hydrocephaly or anencephaly, dandy-walker malformation, hypopituitarism, anophthalmia or microphthalmia, polymicrogyria, cleft lip and palate, hepatic fibrosis and cysts, ambiguous genitalia, and congenital heart defect. majewski et al., (1983) included preaxial polydactyly and bowing of the long bones and shen-schwarz and dave (1988) reported a case with polysplenia and dextrocardia and found two similar cases in the literature. wright et al., (1994) reported two sibs, one of whom was classically affected, whereas the second sib had urethral atresia and preaxial polydactyly of the left foot. nelson et al., (1994) reported a pedigree where the father of three affected sibs, and his cousin, had postaxial polydactyly of both feet. wininger and donnenfeld (1994) found one case of meckel syndrome out of fifteen fetuses prenatally diagnosed with encephaloceles. the condition is genetically heterogenous and two loci have been found so far : 17q21-q24 in 17 finnish families (paavola et al., 1997) and roume et al., 1998 detected another locus at 11q13. cardiac malformations include ventricular or atrial septal defect, aortic hypoplasia or coarctation, aortic valvular stenosis, and rotational anomalies. the condition is autosomal recessive (mim # 249000) with 25% recurrence risk.