Primary Autosomal Recessive Distal Renal Tubular Acidosis Caused by a Common Homozygous SLC4A1 Mutation in Two Lao Families

Primary distal renal tubular acidosis (dRTA) caused by mutations of the SLC4A1 gene, which encodes for erythroid and kidney isoforms of anion exchanger, shows marked difference in inheritance patterns and clinical features in different parts of the world. While the disease shows autosomal dominant inheritance without any red cell morphological abnormalities in the temperate countries, it is almost invariably recessive, and often accompanies red cell morphological abnormalities or hemolytic anemia in the tropics, especially in Southeast Asia. Here, we report three patients with autosomal recessive (AR) dRTA, presenting with typical findings of failure to thrive and rickets, from two unrelated Lao families. The mutational analyses revealed that all three patients harbored the same homozygous SLC4A1 mutation, p.Gly701Asp. Adequate supplementation of alkali and potassium resulted in remarkable improvement of growth retardation and skeletal deformities of the patients. This is the first case report of Lao patients with AR dRTA caused by SLC4A1 mutations.