Ataxia with Oculomotor Apraxia Type 4 with PNKP Common “Portuguese” and Novel Mutations in Two Belarusian Families

Abstract

Ataxia with oculomotor apraxia type 4 (AOA4) is a rare autosomal recessive, <i>PNKP</i> -related disorder delineated in 2015 in Portugal. We diagnosed AOA4 by next generation sequencing (NGS) followed by Sanger's sequencing in three boys from two unrelated Belarusian families. In both families, one of the heterozygous <i>PNKP</i> mutations was c.1123G>T, common in Portuguese patients; biallelic mutations, c.1270_1283dup14 and c.1029+2T>C, respectively, were novel. These are the first reported AOA4 Slavic cases and the first with a "Portuguese" <i>PNKP</i> mutation outside Portugal. Distinction in two brothers was microcephaly but their disease was not severe in contrast to <i>PNKP</i> -related "microcephaly, seizures, and developmental delay" and reported cases with features of both phenotypes.