OBJECTIVETo investigate the clinical features and genetic characteristics of patients with 3-hydroxy-isobutyryl-CoA hydrolase (HIBCH) gene mutations.

METHODThe clinical data of a patient with novel HIBCH mutations were collected, the related literature was searched from China National Knowledge Infrastructure, Wanfang Data Knowledge Service Platform, National Center for Biotechnology Information and PubMed (up to December 2014) by using search terms" HIBCH", "3-hydroxy-isobutyryl-CoA hydrolase" or "beta-Hydroxyisobutyryl CoA Deacylase Deficiency". The clinical features, neuroimage and treatment of the patients with HIBCH gene mutations were studied.

RESULTThe patient was a girl who was born at term after an uneventful pregnancy to non-consanguineous healthy parents, she was hospitalized at 5 years and 5 months of age because of development delay for 5 years and 5 months and abnormal posture on the left of body for more than 10 days. The family history was unremarkable. Her psychomotor development was significantly delayed. Three times brain MRI between 2. 5 years and 5 years of age revealed bilateral symmetrical lesions in basal ganglia. At the age of 5 years and 5 months, she presented with acute encephalopathy and severe extrapyramidal symptoms preceded by fever. At that time, her brain MRI revealed aggravated lesions in bilateral basal ganglia, new lesions in the midbrain cerebral peduncle and pons, and cerebellar atrophy. The results of biochemical tests were normal. A novel compound heterozygous mutation of HIBCH gene, c. 1027C > G, p. H343D and c. 79-1G > T, splicing, were found in the parent. Further study showed that c. 1027 C > G mutation was inherited from her father and c. 79-1 G > T from her mother. Her symptoms were mitigated after "cocktail" therapy and symptomatic treatment. Repeated brain MRI revealed that the lesion in basal ganglia got better, the lesions in brain stem disappeared. Literature relevant to HIBCH published all around the world was reviewed, no Chinese cases with HIBCH gene mutations had been reported, 6 foreign cases with HIBCH gene mutations were reported. Among them, 5 patients were diagnosed as Leigh-like syndrome, with progressive neurodegenerative course, and symmetrical basal ganglia lesions on brain MRI. Another case was reported in 1982, with developmental delay and various physical malformations without data on his brain MRI. HIBCH gene mutational analysis showed that 4 cases had homozygous mutations, which were c. 950G > A (p. G317E) in two brothers, c. 219 _220insTTGAATAG (p. K73fsX86) and c. 1128_1129insT (p. K377X) respectively. Three of them died before 3 years old. Two cases had compound heterozygous mutations: c. 365A > G (p. Y122C) and IVS2-3C > G (p. R27fsX50); c. 517 + 1G > A and c. 410C > T (p. A137V). They were alive at the time of the report.

CONCLUSIONPatients with HIBCH gene mutation mainly presented as Leigh-like syndrome both in clinical manifestation and in neuroimage. HIBCH gene mutational analysis should be performed on children with Leigh-like syndrome, if the mutations of known genes of Leigh syndrome were negative.