Table 1

Comparison of the incidence of phenotype features of selected conditions in which holoprosencephaly is common from literature review*

Our cases†Smith-Lemli-Opitz syndromeYoung-Madders syndromeTrisomy 13SHH mutation phenotype
Mode of inheritanceRecessiveRecessiveRecessiveSporadic dominantAutosomal dominant
Holoprosencephaly (%)4/45100‡3036
Characteristic facies (%)>90>90>9060>60
Cleft lip (%)3/440534020
Congenital heart disease (%)3/45015802
Microcephaly (%)1/480%122010
Male ambiguous genitalia (%)0/2506005
Intellectual deficit range (%)4/4 severeNormal (>5%) to severe100% severe100% severeNormal (30%) to severe
Postaxial polydactyly (%)0/43390‡80<10
2/3 toe syndactyly (%)0/4>9010§
  • *From the references in the text.

  • †As we describe four cases, we give numbers not a percentage.

  • ‡Presumably a bias introduced by the disease definition.

  • §Presumably under-reported.

  • SHH, sonic hedgehog.