HOLOPROSENCEPHALY-POLYDACTYLY (PSEUDOTRISOMY-13) SYNDROME - EXPANSIONOF THE PHENOTYPIC SPECTRUM

Analysis of familial cases of the so called ''holoprosencephaly-polyda ctyly'' (''pseudotrisomy 13'') syndrome shows that neither holoprosenc ephaly, nor polydactyly are obligatory manifestations of this conditio n. This review of previous case reports shows that each of these anoma lies is only found in approximately 60% of affected sibs, and therefor e these sentinel abnormalities are not required for diagnosis. We prop ose a widening of the phenotypic spectrum of this syndrome and conside ration of the use of an eponomic name, such as the Cohen-Gorlin syndro me, or clear recognition that the sentinel findings of holoprosencepha ly and polydactyly are not essential for diagnosis. We propose the fol lowing diagnostic criteria for the syndrome. The diagnostic criteria f or sporadic cases would include a normal karyotype and either (1) a co mbination of holoprosencephaly and postaxial polydactyly with or witho ut other characteristics, or (2) a combination of holoprosencephaly wi th other characteristics but without polydactyly, or (3) a combination of postaxial polydactyly, brain defects (microcephaly, hydrocephaly, agenesis of corpus callosum) and other characteristics. The diagnostic criteria for the familial cases would be the same, except that, as lo ng as the other sibs have no abnormalities contradicting the diagnosis , a normal karyotype would be required in only one affected sib. (C) 1 993 Wiley-Liss, Inc.