Kenia B El-Jaick | PubMed Health

PubMed2006

SIX3 mutations with holoprosencephaly.

Here, we report six Brazilian patients with holoprosencephaly caused by SIX3 mutations. Missense mutations were more common than frameshift mutations. Comparison of patients with missense versus frameshift mutations was essentially unremarkable. Our cases suggest that SIX3 mutations result in a more severe phenotype than other gene mutations for holoprosencephaly. One patient had a double SIX3 mutation, which has not been reported previously. In our SIX3 mutations, three were transmitted by the paternal side, two were transmitted by the maternal side, and one was a de novo event. Mutations in normal parents with severe involvement of their offspring does not allow prediction of phenotypic severity, which makes genetic counseling difficult.

Brain↗

PubMed2006

Functional analysis of mutations in TGIF associated with holoprosencephaly.

Holoprosencephaly (HPE) is the most common structural malformation of the forebrain and face in humans. Our current understanding of the pathogenesis of HPE attempts to integrate genetic susceptibility, evidenced by mutations in the known HPE genes, with the epigenetic influence of environmental factors. Mutations or deletions of the human TGIF gene have been associated with HPE in multiple population cohorts. Here we examine the functional effects of all previously reported mutations, and describe four additional variants. Of the eleven sequence variations in TGIF, all but four can be demonstrated to be functionally abnormal. In contrast, no potentially pathogenic sequence alterations were detected in the related gene TGIF2. These results provide further evidence of a role for TGIF in HPE and demonstrate the importance of functional analysis of putative disease-associated alleles.

Animals↗