HOXA1 gene consists of two exons (coding regions which makes the protein). Majority of the mutations found in both of these diseases are found in exon 1, and lead to the loss of complete function of HOXA1 protein. Additionally, mutations which cause replacement of amino acids (missense variants) are also reported. The two most common variants reported for ABDS and BSAS are c.76C>T p.Arg26Ter and c.175dup p.Val59GlyfsTer119 respectively in homozygous state (both the copies of gene are mutated). As HOXA1 is a small gene with only two exons, sequencing of HOXA1 should be the first choice of the genetic test, provided the clinical features are suggestive of these diseases. If there are heterogeneous clinical features, then exome sequencing should be preferred.
HOXA1