Low back pain as a presenting symptom in GNE myopathy

@#GNE myopathy is a rare autosomal recessive early adult-onset myopathy with slow progression that preferentially affects the tibialis anterior muscles and commonly spares the quadriceps femoris muscles. It is caused by biallelic mutations in GNE gene encoding for a single protein with key enzymatic activities in sialic acid biosynthetic pathway. However, diagnosing GNE myopathy can be challenging due to its phenotypic variability. This is the report of a 35-year-old man with GNE myopathy who presented with a low back pain for four years. A lumbar magnetic resonance imaging showed atrophy of lumbar paraspinal muscles. GNE myopathy was confirmed by genetic analysis. This case is unique and broaden the early clinical spectrum of GNE myopathy.

Characteristics of muscle MRI of lower limbs in patients with GNE myopathy / 中华放射学杂志

Objective To summarize the characteristic of muscle MRI of lower limbs in patients with GNE myopathy and to explore the correlation between the fatty degenerative score of muscle MRI and clinical phenotype.Methods This was a prospective study. Seventeen patients with genetically confirmed GNE myopathy,having lower limb muscle MRI test and completed clinical and laboratory data.The degree of fatty degeneration in 18 muscles of lower limbs in each patient was grading.According to the GM-W score, these patients were divided into two groups.GM-W score≤3 were divided into mild group(n=8)and GM-W score≥ 4 were divided into severe group(n=9). Kruskal-Wallis test was used to compare the fatty degenerative score in different muscles of the thigh and the calf level;Mann-Whitney U test was used to compare score of the same muscle between mild and severe group;Spearman rank correlation test was used to analysis the relationship between fatty degenerative score and the course of disease (year), GM-W score, creatinine kinase (IU/L), respectively.Results At the thigh level, the most severely involved muscle of GNE myopathy was semi-tendinosusand adductor, followed by semi-membranous, biceps femoris and gracilis. There was no statistically significant difference in the fatty degenerative score of the above-mentioned muscles (P=0.058). At the calf level, the most severely involved muscle was medial of soleus which score was 4.0(3.0, 4.0), followed by tibialis anterior,extensor digitorum longus and lateral of soleus. There was no significant difference of the above (P=0.259).The fatty degenerative score showed difference between the mild and severe group at sartorius and adductor(P<0.05).At the calf level,the fatty degenerative score in peroneus longus, medial of soleus, lateral of soleus, medial of gastrocnemius and lateral of gastrocnemius showed difference between groups(P<0.05).The total score of fatty degenerative of Lower limb muscles was positively correlated with GM-W score(r=0.730, P<0.05). There were positive correlations between the score of fatty degenerative of the sartorius,peroneal longus,lateral of soleus,medial of gastrocnemius, lateral of gastrocnemius and the GM-W scores( r=0.630,0.845,0.569,0.591,0.640, 0.659,P<0.05).The total score of fatty degenerative of Lower limb muscles was not correlated with the level of creatine kinase(P=0.582), course of disease(P=0.601) and age of onset(P=0.850). Conclusions GNE myopathy in the thigh level within the adductor muscle and posterior muscle involvement, calf level to the tibial anterior muscle early involvement. The total score of fatty degenerative of lower limb muscles is positively correlated with GM-W score,but not correlated with the level of creatine kinase,course of disease and age of onset.

Novel Mutation of the GNE Gene Presenting Atypical Mild Clinical Feature: A Korean Case Report

Glucosamine (UDP-N-acetyl)-2-epimerase/N-acetylmannosamine kinase (GNE) myopathy is caused by mutations in GNE, a key enzyme in sialic acid biosynthesis. Here, we reported a case of GNE that presented with atypical mild clinical feature and slow progression. A 48-year-old female had a complaint of left foot drop since the age of 46 years. Electromyography (EMG) and muscle biopsy from left tibialis anterior muscle were compatible with myopathy. Genetic analysis led to the identification of c.1714G>C/c.527A>T compound heterozygous mutation, which is the second most frequent mutation in Japan as far as we know. Previous research has revealed that c.1714G>C/c.527A>T compound heterozygous mutation is a mild mutation as the onset of the disease is much later than the usual age of onset of GNE myopathy and the clinical course is slowly progressive. This was the first case report in Korea of the clinicopathological characteristics of GNE myopathy with GNE (c.1714G>C/c.527A>T compound heterozygous) mutation.

A Case of GNE Myopathy Presenting a Rapid Deterioration during Pregnancy

BACKGROUND: GNE myopathy is characterized by early-adult-onset distal myopathy sparing quadriceps caused by mutations in the GNE gene encoding UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase, an enzyme in the sialic-acid synthesis pathway. CASE REPORT: A 27-year-old Korean woman presented a rapid deterioration in strength of the distal lower limbs during her first pregnancy. She was diagnosed with GNE myopathy and carrying the compound heterozygous mutations of the GNE gene (D208N/M29T). CONCLUSIONS: This is a representative case implying that an increased requirement of sialic acid during pregnancy might trigger a clinical worsening of GNE myopathy.