Inherited variants of human red cell carbonic anhydrases

The present state of knowledge concerning the genetic control of human red cell carbonic anhydrases I and II (CA I and CA II) is reviewed. A total of 25 electrophoretic variants, and one deficiency variant of CA I, and 7 electrophoretic variants of CA II have been discovered after screening a minimum of about 50,000 (CA I) and 39,000 (CA II) individual bloods from a variety of human populations. The amino acid substitution has been determined for 8 of the CA I variants and one of the CA II variants. Three previously undescribed variants of CA I (CA I Montreal-1, CA I Montreal-2, and CA I Montreal-3) and two new variants of CA II (CA II London and CA II Detroit) are reported. Three of the CA I variants (CA I Australia-1, CA I Bombay, and CA I Mindanao), and four of the CA II variants (CA II2, CA II Australia, CA II Bombay, and CA II Baniwa) were observed to occur at frequencies of greater than 1%; however, CA I Bombay, CA I Mindanao, CA II Bombay, and CA II Baniwa appear to be private polymorphisms limited to small populations. None of the electrophoretic variants, or the CA I deficiency variant, even in the homozygous state, appear to be associated with any clinical disorder. A defective form of CA I reported as possibly responsible for an inherited type of renal tubular acidosis has not been characterized sufficiently to exclude the possibility of secondary effects.