3-Hydroxyisobutyryl-CoA hydrolase deficiency in an Iranian child with novel HIBCH compound heterozygous mutations

A Fatal Case of 3-Hydroxyisobutyryl-CoA Hydrolase Deficiency in a Term Infant with Severe High Anion Gap Acidosis and Review of the Literature

3-hydroxy isobutyl-CoA hydrolase (HIBCH) deficiency is a recently described, rare inborn error of valine metabolism associated with a Leigh syndrome-like phenotype, neurodegenerative symptoms, and caused by recessive mutations in the HIBCH gene. We report the most severe case to date of an intrauterine growth-restricted term male who presented with severe acidosis and a high anion gap soon after birth. The manifestation was fatal that led to death within 36 hours of life. The diagnosis was made postnatally by Whole Genome Sequencing (WGS). We report a rapid and fatal event of HIBCN in a neonate and review of the literature.

Paroxysmal Dyskinesias Revealing 3-Hydroxy-Isobutyryl-CoA Hydrolase (HIBCH) Deficiency

Paroxysmal dyskinesias (PD) are rare movement disorders characterized by recurrent attacks of dystonia, chorea, athetosis, or their combination, with large phenotypic and genetic heterogeneity. 3-Hydroxy-isobutyryl-CoA hydrolase (HIBCH) deficiency is a neurodegenerative disease characterized in most patients by a continuous decline in psychomotor abilities or a secondary regression triggered by febrile infections and metabolic crises.We describe two PD patients from two pedigrees, both carrying a homozygous c.913A > G, p.Thr305Ala mutation in the HIBCH gene, associated with an unusual clinical presentation. The first patient presented in the second year of life with right paroxysmal hemidystonia lasting for 30 minutes, without any loss of consciousness and without any triggering factor. The second patient has presented since the age of 3 recurrent exercise-induced PD episodes which have been described as abnormal equinovarus, contractures of the lower limbs, lasting for 1 to 4 hours, associated with choreic movements of the hands. Their neurological examination and metabolic screening were normal, while brain magnetic resonance imaging showed abnormal signal of the pallidi.We suggest that HIBCH deficiency, through the accumulation of metabolic intermediates of the valine catabolic pathway, leads to a secondary defect in respiratory chain activity and pyruvate dehydrogenase (PDH) activity and to a broad phenotypic spectrum ranging from Leigh syndrome to milder phenotypes. The two patients presented herein expand the spectrum of the disease to include unusual paroxysmal phenotypes and HIBCH deficiency should be considered in the diagnostic strategy of PD to enable adequate preventive treatment.

3-Hydroxyisobutyryl-CoA Hydrolase (HIBCH) Deficiency Cases Diagnosed by Only HIBCH Gene Analysis and Novel Pathogenic Mutation

Objective:

3-Hydroxyisobutyryl-CoA hydrolase (HIBCH) deficiency is a rare metabolic disease of valine metabolism. Only 22 cases of HIBCH deficiency have been reported in the literature. Our algorithm could help in the diagnosis of this disease.

Methods:

HIBCH gene analysis was performed in all cases.

Results:

The common features of our five patients from the same family with a developmental delay, seizures, and neurological regression were the elevation of 3-hydroxy-isobutyryl-carnitine and Leigh-like abnormalities. Unlike other patients in the literature, our patients were diagnosed with HIBCH gene analysis, rather than whole exome sequencing (WES). In all our cases, a missense c.452C>T, p. Ser151Leu homozygous novel pathogenic mutation was detected in the HIBCH gene.

Conclusion:

In cases where HIBCH deficiency is considered in our differential diagnosis algorithm, HIBCH gene analysis, which is cost-effective, should be performed instead of WES, and the number of cases should be increased in the literature.

3-Hydroxyisobutyryl-CoA hydrolase deficiency in an infant with developmental delay and high anion gap acidosis

Due to the rarity of this disorder, paying attention to diagnostic clues is important. Low valine formula seems to be effective in improvement of patient's symptoms. Prevention of consanguineous marriage is the best way to prevent this disease.

Cinical, Metabolic, and Genetic Analysis and Follow-Up of Eight Patients With HIBCH Mutations Presenting With Leigh/Leigh-Like Syndrome

3-Hydroxyisobutyryl-CoA hydrolase (HIBCH, NM_014362.3) gene mutation can cause HIBCH deficiency, leading to Leigh/Leigh-like disease. To date, few case series have investigated the relationship between metabolites and clinical phenotypes or the effects of treatment, although 34 patients with HIBCH mutations from 27 families have been reported. The purpose of this study was to analyze the phenotypic spectrum, follow-up results, metabolites, and genotypes of patients with HIBCH deficiency presenting with Leigh/Leigh-like syndrome and explore specific metabolites related to disease diagnosis and prognosis through retrospective and longitudinal studies. Applying next-generation sequencing, we identified eight patients with HIBCH mutations from our cohort of 181 cases of genetically diagnosed Leigh/Leigh-like syndrome. Six novel HIBCH mutations were identified: c.977T>G [p.Leu326Arg], c.1036G>T [p.Val346Phe], c.750+1G>A, c.810-2A>C, c.469C>T [p.Arg157*], and c.236delC [p.Pro79Leufs*5]. The Newcastle Pediatric Mitochondrial Disease Scale (NPMDS) was employed to assess disease progression and clinical outcomes. The non-invasive approach of metabolite analysis showed that levels of some were associated with clinical phenotype severity. Five (5/7) patients presented with elevated C4-OH in dried blood spots, and the level was probably correlated with the NPMDS scores during the peak disease phase. 2,3-Dihydroxy-2-methylbutyrate in urine was elevated in six (6/7) patients and elevated S-(2-caboxypropyl)cysteamine in urine was found in three patients (3/3). The median age at initial presentation was 13 months (8–18 months), and the median follow-up was 2.3 years (range 1.3–7.2 years). We summarized and compared with all reported patients with HIBCH mutations. The most prominent clinical manifestations were developmental regression/delay, hypotonia, encephalopathy, and feeding difficulties. We administered drug and dietary treatment. During follow-up, five patients responded positively to treatment with a significant decrease in NPMDS scores. Our research is the largest case series of patients with HIBCH mutations.

Delineating the neurological phenotype in children with defects in the ECHS1 or HIBCH gene

The neurological phenotype of 3-hydroxyisobutyryl-CoA hydrolase (HIBCH) and short-chain enoyl-CoA hydratase (SCEH) defects is expanding and natural history studies are necessary to improve clinical management. From 42 patients with Leigh syndrome studied by massive parallel sequencing, we identified five patients with SCEH and HIBCH deficiency. Fourteen additional patients were recruited through collaborations with other centres. In total, we analysed the neurological features and mutation spectrum in 19 new SCEH/HIBCH patients. For natural history studies and phenotype to genotype associations we also included 70 previously reported patients. The 19 newly identified cases presented with Leigh syndrome (SCEH, n = 11; HIBCH, n = 6) and paroxysmal dystonia (SCEH, n = 2). Basal ganglia lesions (18 patients) were associated with small cysts in the putamen/pallidum in half of the cases, a characteristic hallmark for diagnosis. Eighteen pathogenic variants were identified, 11 were novel. Among all 89 cases, we observed a longer survival in HIBCH compared to SCEH patients, and in HIBCH patients carrying homozygous mutations on the protein surface compared to those with variants inside/near the catalytic region. The SCEH p.(Ala173Val) change was associated with a milder form of paroxysmal dystonia triggered by increased energy demands. In a child harbouring SCEH p.(Ala173Val) and the novel p.(Leu123Phe) change, an 83.6% reduction of the protein was observed in fibroblasts. The SCEH and HIBCH defects in the catabolic valine pathway were a frequent cause of Leigh syndrome in our cohort. We identified phenotype and genotype associations that may help predict outcome and improve clinical management.

MRI of 3-hydroxyisobutyryl-CoA hydrolase (HIBCH) deficiency

3-Hydroxyisobutyryl-CoA hydrolase (HIBCH) deficiency is a rare mitochondrial disorder of valine metabolism which may present with motor delay, hypotonia, ataxia, dystonia, seizures poor feeding, and organic aciduria. Neuroimaging findings include signal abnormalities of the deep gray matter, particularly the globus pallidi, and cerebral peduncles. We report a 15-month-old male patient with HIBCH deficiency who presented with paroxysmal tonic upgaze of infancy, motor delay, and hypotonia. MRI revealed characteristic bilateral, symmetric signal abnormalities in the basal ganglia and a mutation in HIBCH was confirmed with whole exome sequencing. HIBCH should be a consideration in patients with Leigh-like features, especially if neuroimaging changes primarily affect the globus pallidi. Recognition of this pattern may help guide targeted testing and expedite the diagnosis and treatment of this rare disease.

A phenotypically severe, biochemically "silent" case of HIBCH deficiency in a newborn diagnosed by rapid whole exome sequencing and enzymatic testing

3-Hydroxyisobutyryl-CoA dehydrogenase (HIBCH) deficiency is a rare error in valine catabolism associated with a Leigh syndrome-like phenotype, mitochondrial dysfunction, and increased C4-OH. We report the most severe case to date in a full-term female who presented with poor feeding and nystagmus on day of life (DOL) 1. Although initial neuroimaging findings were concerning for metabolic disease, further metabolic testing was nondiagnostic and she was discharged on DOL 18. She was readmitted on DOL 22 after severe apneic episodes requiring intubation, with EEG demonstrating multifocal seizures and MRI/MRS demonstrating worsening findings. Care was withdrawn DOL 27 and she expired. Rapid whole exome sequencing (WES) demonstrated compound heterozygous variants in HIBCH with a paternal pathogenic variant (c.852delA, p.L284FfsX10) and a maternal likely pathogenic variant (c.488G>T, p.C163F). Fibroblast enzymatic testing demonstrated marked reduction in HIBCH levels. This case demonstrates the importance of rapid WES and follow-up functional testing in establishing a diagnosis when metabolic disease is suspected but lacks an expected biochemical signature.