Novel Sonic Hedgehog Mutation in a Couple with Variable Expression of Holoprosencephaly

Holoprosencephaly (HPE) is the most common developmental defect of the forebrain and midface in humans. sporadic and inherited mutations in the human sonic hedgehog (SHH) gene cause 37% of familial HPE. A couple was referred to our unit with a family history of two spontaneous first trimester miscarriages and a daughter with HPE who presented early neonatal death. The father had a repaired median cleft lip, absence of central incisors, facial medial hypoplasia, and cleft palate. Intelligence and a brain CT scan were normal. Direct paternal sequencing analysis showed a novel nonsense mutation (W127X). Facial characteristics are considered as HPE microforms, and the pedigree suggested autosomal dominant inheritance with a variable expression of the phenotype. This study reinforces the importance of an exhaustive evaluation of couples with a history of miscarriages and neonatal deaths with structural defects.