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.