In this study, we aim at defining detailed clinical and genetic characteristics of GNE myopathy in a cohort from Turkey.

GNE myopathy is an autosomal recessive adult-onset progressive myopathy caused by mutations in GNE. A limited number of GNE myopathy cases have been reported from Turkey, and the genotypic and phenotypic features of GNE myopathy in this population remain unclear.

Twelve patients, who were diagnosed with GNE myopathy on the basis of clinical and genetic findings, followed between 1992 and 2018 at our Department were included in the study.

We studied the clinical and genetic characteristics of GNE myopathy in 12 patients (5 male, 7 female) from eight unrelated families. Mean age of onset was 22.3 ± 5.88 years. Marked intrafamilial variability in age of onset was noted in two families. Mean follow-up time was 16.8± 4.6 years. The most common presenting symptom was gait disturbance or difficulty in walking due to distal lower extremity weakness (11/12). Only one patient, who carried homozygous c.1985 C>T mutation, presented with weak grip in addition to drop foot drop. Neurological examination of patients revealed weakness in distal lower extremities with a predilection for tibialis anterior muscle at early stage of the disease, followed by proximal lower extremity involvement with relative sparing of quadriceps femoris muscle until advanced stages of disease. Six different mutations in GNE were identified in our cohort, four of them were novel (c.184G>A, c.1676G>C, c.1775C>T, c.51+13717 51+13718insAA).

We detailed the clinical characteristics of GNE myopathy patients from Turkey and described novel mutations in GNE, including an insertion mutation in the promoter region.  Considering the specific therapies for GNE myopathy which are under investigation, it is important to reach the utmost of patients and to establish early and accurate diagnosis in patients with GNE myopathy.