Neonatal Presentation of a Case of Carbonic Anhydrase VA Deficiency.

Carbonic anhydrase VA (CA-VA) deficiency is a rare mitochondrial disorder affecting bicarbonate-dependent metabolic pathways. It commonly presents in neonates with hyperammonemia, lactic acidosis, and metabolic crisis, often mimicking more prevalent urea cycle and organic acid disorders. This rare metabolic disorder has been reported across different populations, with cases documented worldwide. We report the case of a three-day-old full-term Indian female neonate presenting with lethargy and poor feeding. Initial labs revealed hyperammonemia, severe lactic acidosis, hypoglycemia, and ketosis. Despite ammonia scavenger therapy, hyperammonemia persisted, necessitating continuous renal replacement therapy. Metabolic workup suggested mitochondrial dysfunction. Genetic testing identified a homozygous exon 6 deletion in the CA5A gene, confirming CA-VA deficiency. She was discharged on carglumic acid and supplements, with clinical and biochemical improvement. CA-VA deficiency should be included in the differential diagnosis of neonatal metabolic decompensation, particularly in South Asian infants. Early intervention can lead to favorable outcomes, underscoring the importance of prompt metabolic and genetic evaluation.