Pseudotrisomy 13: clinical findings and genetic implications.

The combination of holoprosencephaly, postaxial polydactyly, and normal karyotype has been termed pseudotrisomy 13 syndrome. Here, we report the prenatal diagnosis of pseudotrisomy 13 in three siblings suggesting autosomal recessive inheritance of this syndrome. Clinical overlap with hydrolethalus syndrome, Smith-Lemli-Opitz syndrome, Meckel syndrome, and Pallister-Hall syndrome is discussed.