A Novel Variant in an Israeli Bedouin Family: The First Reported Cases of Carbonic Anhydrase VA (CA5A) Deficiency in Israel.

Carbonic anhydrase VA (CA5A) deficiency (OMIM 615751) is an ultra-rare inborn error of metabolism, presenting in newborns, infants, and young children with a pentad of encephalopathy, hyperammonemia, lactic acidosis, ketonuria, and hypoglycemia. We present two cases: a case of a healthy Bedouin infant admitted with hyperammonemic encephalopathy that required urgent hemodialysis, and her younger sibling, who presented with a milder episode. Molecular analysis confirmed the diagnosis of CA5A deficiency due to a homozygous missense variant in the CA5A gene. Both patients had a favorable outcome with continued normal development. These were the first identified cases of CA5A deficiency in the Bedouin population, emphasizing the importance of a high index of suspicion, early genetic consultation and diagnosis, and prompt treatment at the earliest possible stage of a hyperammonemic crisis.