A novel compound heterozygous mutation in a Chinese boy with L-2-hydroxyglutaric aciduria: a case study

Abstract

Background: L-2-hydroxyglutaric aciduria is a rare autosomal recessive encephalopathy caused by mutations in the L-2-hydroxyglutarate dehydrogenase gene. We describe some novel clinical and molecular characteristics found in a boy with L-2-hydroxyglutaric aciduria.

Case presentation: We report an 8-year-old Chinese boy, who had characteristic developmental delay, ataxia and acrocephaly as the main symptoms. He also complained of paroxysmal headache and palpitation. Brain image revealed a symmetrical, extensive subcortical white matter lesion. Urine test for organic acids showed a significantly increased level of 2-hydroxyglutaric acid (106.74 mmol/mol cre, normal range 0.6 ~ 5.9 mmol/mol cre), leading to the diagnosis of L-2-hydroxyglutaric aciduria. Genetic testing uncovered two heterozygous missense mutations in L-2-hydroxyglutarate dehydrogenase gene: c.169G > A in exon 2 and c.542G > T in exon 5, not hitherto been described.

Conclusion: Novel gene mutation and associated clinical symptoms can contribute for the understanding and identification of this rare disease. Possible genotype-phenotype correlation waits for further study.

Fig. 1

The patient’s brain magnetic resonance image (MRI). Axial T2-weighted sequence of the brain MRI showed symmetrical subcortical white matter hyperintense involving bilateral dentate nucleus, internal capsule, external capsule, and corona radiate

Fig. 2

The patient’s urinary organic acid screening with GC-MS, showing increased 2-hydroxyglutaric acid concentrations

Fig. 3

The patient’s L-2HGDH gene mutations. The patient’s L-2HGDH gene test showed two heterozygous mutations: c.542G > T in exon5 and c.169G > A in exon2