ZIC2 Repeat Expansion Testing

Description

Pathogenic GCN repeat expansions within exon 3 of the ZIC2 gene have been associated with autosomal dominant holoprosencephaly 5 syndrome (HPE5). The pathogenic repeat expansions lead to an extended polyalanine tract that can impair DNA binding and the transcriptional activities of the protein 1.

Pathogenicity is dependent upon GCN repeat length according to the following ranges 1-2:

Normal Alleles

Mutable Normal Alleles

Intermediate/Uncertain Alleles

Reduced Penetrance Alleles

Full Penetrance Alleles

15

-

16-24

-

25 or more

Tests That Analyze ZIC2 Repeats