Phenotypic manifestations of the autosomal recessive form of VACTERL-hydrocephaly syndrome (David-O'Callaghan syndrome) and the X-linked recessive form (Hunter-MacMurray) syndrome are almost identical. The absence of cardiovascular malformations in cases with undoubtedly X-linked inheritance may be the only exception. The comparison of patients with David-O'Callaghan syndrome and nonclassified sporadic cases of VACTERL-hydrocephaly showed two marked differences. First, radial involvement (usually bilateral) occurred in all familial but only in 22 of 36 sporadic cases. Therefore, radial noninvolvement may be evidence against a genetic origin of the complex in a sporadic case. Second, predominantly severe forms of cardiovascular malformations were found in cases of David-O'Callaghan syndrome, whereas in sporadic cases almost all cardiovascular malformations were simple defects with minimal, if any, hemodynamic disturbances. The similarity of the spectrum and frequency of main manifestations of David-O'Callaghan and von Voss-Cherstvoy syndromes allows us to think that both of these syndromes actually might be 2 forms of one genetic entity. There are some syndromes with abnormalities of the brain (different for each syndrome) sharing the same limb defects (mainly preaxial), congenital heart defects, abnormalities of kidneys, and anal atresia/ectopia. Baller-Gerold syndrome, Steinfeld syndrome, XK-aprosencephaly, and DK-phocomelia (von Voss-Cherstvoy) syndrome as well as Mendelian forms of VACTERL-hydrocephaly syndromes fit into this "cerebro-cardio-radio-reno-rectal community."