A New Case of 3 –Hydroxyisobutyryl-CoA Hydrolase (HIBCH) Deficiency

Introduction:3–Hydroxyisobutyryl-CoA hydrolase (HIBCH) deficiency considered to be distinctively rare autosomal recessive disorder in Valine metabolism. Its presentation is usually episodes of ketoacidosis and Leigh-like basal ganglia disease without high concentration of pyruvate and lactate in the cerebrospinal fluid, neurodevelopmental and motor delay, dystonia and ataxia. HIBCHD is very rare metabolic disorder and the incidence estimated of 1 in 128000 live births in Asia. It is a very rare disorder, so characteristics, gene mutations, molecular mechanism, etc. are not well defined. Thus it is essential to pay attention to cases which suspected of HIBCH deficiency.Materials & Methods: A 2 year old girl was the first child of non-sanguineous parents presented with clinical findings consistent with developmental delay, seizure and Leigh- like abnormality showing on the brain Magnetic Resonance Imaging (MRI).Results: The results of Electroencephalography and echocardiography were normal. Elevation of 3-hydroxyisovaleric acids in urine and some amino acids especially Gln and Ala in plasma were reported by HPLC analysis. PH was normal and lactate and NH4 were not increased. Whole exome sequencing showed two different variants in HIBCH gene as well as two likely pathogenic variants in Otogelin (OTOGL) gene. Conclusion & discussion: According to best of our knowledge this is the first case of HIBCH deficiency with two likely pathogenic variants in OTOGL gene, an important gene family for development of ear in vertebraes. We have suggested MSUD milk concomitant by taking Isoleucine and Leucine to manage branched chain amino acid amount. Gln and Ala amount could be followed to decide the appropriate level of Isoleucine and Leucine. Carbohydrate- rich meals are also recommended to avoid fasting

Keywords:

HIBCH deficiency , Leigh-like syndrome , OTOGL gene