Wilson's Disease and Hyperornithinemia-hyperammonemia-homocitrullinuria Syndrome in a Child: A Case Report with Lessons Learned!

BACKGROUND: Wilson's disease (WD) is a rare disorder of copper toxicosis. Hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome is even rarer. The coexistence of these two disorders and their clinical implications are not yet reported. We report on a child who succumbed to death due to liver disease caused by both disorders, documenting their disease-causing mutations and highlighting the lessons learnt out of this case. CASE DESCRIPTION: A child who was diagnosed to have WD soon after birth due to known parental heterozygosity was later found to have developmental delay, seizures, and hyperammonemia. Subsequent evaluation confirmed hyperornithinemia-hyperammonamia-homocitrullinuria (HHH) syndrome as a comorbidity. Though this child was commenced on medical treatment for both the metabolic diseases since early life, his liver disease was rapidly progressive requiring a liver transplant (LTx) at 6-years. He died in the posttransplant period possibly due to sepsis and hidden metabolic consequences. CONCLUSION: This case highlights that co-occurrence of WD and HHH syndrome would cause progressive liver disease despite medical treatment. Hence, the close clinical follow-up and early LTx would be warranted. HOW TO CITE THIS ARTICLE: Fernando M, Vijay S, Santra S, et al. Wilson's Disease and Hyperornithinemia-hyperammonemia-homocitrullinuria Syndrome in a Child: A Case Report with Lessons Learned! Euroasian J Hepato-Gastroenterol 2021;11(2):100-102.

Expanding the genetic and phenotypic spectrum of branched-chain amino acid transferase 2 deficiency.

The first step in branched-chain amino acid (BCAA) catabolism is catalyzed by the two BCAA transferase isoenzymes, cytoplasmic branched-chain amino acid transferase (BCAT) 1, and mitochondrial BCAT2. Defects in the second step of BCAA catabolism cause maple syrup urine disease (MSUD), a condition which has been far more extensively investigated. Here, we studied the consequences of BCAT2 deficiency, an ultra-rare condition in humans. We present genetic, clinical, and functional data in five individuals from four different families with homozygous or compound heterozygous BCAT2 mutations which were all detected following abnormal biochemical profile results or familial mutation segregation studies. We demonstrate that BCAT2 deficiency has a recognizable biochemical profile with raised plasma BCAAs and, in contrast with MSUD, low-normal branched-chain keto acids (BCKAs) with undetectable l-allo-isoleucine. Interestingly, unlike in MSUD, none of the individuals with BCAT2 deficiency developed acute encephalopathy even with exceptionally high BCAA levels. We observed wide-ranging clinical phenotypes in individuals with BCAT2 deficiency. While one adult was apparently asymptomatic, three individuals had presented with developmental delay and autistic features. We show that the biochemical characteristics of BCAT2 deficiency may be amenable to protein-restricted diet and that early treatment may improve outcome in affected individuals. BCAT2 deficiency is an inborn error of BCAA catabolism. At present, it is unclear whether developmental delay and autism are parts of the variable phenotypic spectrum of this condition or coincidental. Further studies will be required to explore this.