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Cohen and Gorlin (1991) coined the term
pseudotrisomy 13 syndrome to designate cases of holoprosencephaly,
severe facial anomalies, postaxial polydactyly, various other
congenital defects, and normal chromosomes. They summarized 11
examples. Two pairs of sibs (Atkin, 1988;
Bachman et al., 1990) and 2 other cases
with consanguinity suggested autosomal recessive inheritance.
Cohen and Gorlin (1991) suggested that
alternatively an undetected microdeletion or etiologic heterogeneity,
some cases possibly representing dominant new mutations, should be
considered. Cohen and Gorlin (1991)
concluded that the cases reported by Bachman et
al. (1990) were instances of this syndrome and not of the
hydrolethalus syndrome. These were the only cases so labeled that had
frank holoprosencephaly. The other cases from the literature cited by
Bachman et al. (1990) as holoprosencephaly
in hydrolethalus syndrome were thought by Cohen
and Gorlin (1991) to be in error. Verloes
et al. (1991) observed 5 unrelated children with the syndrome.
They commented on the phenotypic overlap not only with the
hydrolethalus syndrome (236680)
but also with lethal acrodysgenital dwarfism (Smith-Lemli-Opitz
syndrome, type II; 268670).
Hennekam et al. (1991) emphasized the
occurrence of heart defect with holoprosencephaly and postaxial
polydactyly. The first patient with the combination was described by
Young and Simpson (1987). Hennekam
et al. (1991) reported male and female sibs, the offspring of
second-cousin parents. Relevant to this syndrome may be the analysis
of Brown et al. (1993) which defined band
13q32 as being associated particularly with major malformations and
digital abnormalities. Patients with more distal deletions had severe
mental retardation but did not have major malformations or growth
retardation. Seller et al. (1993) diagnosed
prenatally 2 sibs with holoprosencephaly, midface hypoplasia, and
normal chromosomes. One of the sibs also had polydactyly. They
suggested that this represents an example of the autosomal recessive
pseudotrisomy 13 syndrome.
Ramos-Arroyo et al. (1994) reported the
case of a baby with holoprosencephaly, median cleft lip, cardiac and
genital anomalies, normal upper limbs, and a normal 46,XX karyotype.
Hewitt et al. (1989) suggested restrictive
clinical diagnostic criteria of holoprosencephaly and polydactyly and
Verloes et al. (1991) had recommended the
use of the term holoprosencephaly-polydactyly syndrome. The patient
reported by Ramos-Arroyo et al. (1994)
would not satisfy the more restrictive criteria. This is a instance
of uncertainty between variable expression and basic heterogeneity.
They reviewed reports of 22 cases of pseudotrisomy syndrome and found
postaxial polydactyly in 19 and preaxial polydactyly in 1.
Victor A. McKusick : 6/10/1991
terry : 3/27/1996
mark : 3/14/1996
terry : 2/26/1996
mimadm : 3/12/1994
carol : 12/16/1993
carol : 3/25/1993
carol : 1/25/1993
supermim : 3/17/1992
carol : 12/19/1991