COLOBOMA, MENTAL-RETARDATION, HYPOGONADISM, AND OBESITY - CRITICAL-REVIEW OF THE SO-CALLED BIEMOND SYNDROME TYPE-2, UPDATED NOSOLOGY, AND DELINEATION OF 3 NEW SYNDROMES

Biemond syndrome type 2 (BS2) is classically regarded as a recessively inherited condition (MIM 210350) comprising mental retardation, colob oma, obesity, polydactyly, hypogonadism, hydrocephalus, and facial dys ostosis. Clinically, the disorder is closely related to Bardet-Biedl s yndrome. Few cases have been reported, most of them before 1970. We pr esent clinical data on three mentally retarded sporadic cases with col oboma, obesity, and hypogenitalism (in two of them), fitting at first glance a diagnosis of BS2. A review documents striking clinical variab ility among the patients said to have BS2. We propose a new nosology o f those cases and delineate several new clinical forms. Purported BS2 cases may be divided into: (1) Bardet-Biedl syndrome with fortuitous c oloboma or aniridia, (2) BS2 sensu stricto, a recessively inherited sy ndrome of sexual infantilism, short stature, coloboma, and preaxial po lydactyly without obesity, only known from the original report, (3) a ''new'' dominantly inherited form of colobomatous microphthalmia occas ionally associated with obesity, hypogonadism, and mental retardation, to which our observations belong, (4) cytogenetically proven Rubinste in-Taybi syndrome (one case), (5) an unclassifiable, early lethal fami lial syndrome resembling Buntinx-Majewski syndrome, and (6) a ''new'' coloboma-zygodactyly-clefting syndrome. The latter two syndromes may r esult from chromosomal anomaly. (C) 1997 Wiley-Liss, Inc.