Friedreich ataxia in classical galactosaemia

Abstract

Movement disorders such as ataxia are a recognized complication of classical galactosaemia, even in diet-compliant patients. Here, we report the coexistence of classical galactosaemia and Friedreich ataxia (FRDA) in nine children from seven Irish Traveller families. These two autosomal recessive disorders, the loci for which are located on either side of the centromere of chromosome 9, appear to be in linkage disequilibrium in this subgroup. Both conditions are known to occur with increased frequency amongst the Irish Traveller population. Each member of our cohort had been diagnosed with galactosaemia in the neonatal period, and all are homozygous for the common Q188R mutation in the GALT gene. Eight of the nine patients later presented with progressive ataxia, between the ages of 5–13 years. Another child presented in cardiac failure secondary to dilated cardiomyopathy at 7 years of age. He was not ataxic at presentation and, one year from diagnosis, his neurological examination remains normal. The diagnosis of FRDA was confirmed by detecting the common pathogenic GAA expansion in both alleles of the frataxin gene (FXN) in each patient. Neurological symptoms are easily attributed to an underlying diagnosis of galactosaemia. It is important to consider a diagnosis of Friedreich ataxia in a child from the Irish Traveller population with galactosaemia who presents with ataxia or cardiomyopathy.