Hypohaptoglobinæmia in an American Negro Family

WITH the demonstration that random population pairs and dizygotic twins show greater intra-pair variability than monozygotic twins in serum haptoglobin (Hp) level, evidence for the genetic regulation of this protein has been presented 1 . This work also demonstrated that the normal values for haptoglobin phenotypes Hp 2–2 and Hp 2–1 are lower than those for Hp 1–1. If these differences are genetically determined, a similar mechanism involving the Hp 2 allele may be operative in a benign, genetically determined deficiency of serum haptoglobin 2–4 . A family of Dominican descent in which nine members drawn from two generations had haptoglobin-levels ranging from 6 to 52 mg/100 ml. and Hp 2–1 and Hp 2–2 phenotypes has also been reported 5 . On the basis of the available pedigrees, inheritance of this trait via a recessive haptoglobin allele ( Hp °) or a simple non-allelic dominant has been excluded. Although so far all Caucasians with hypohaptoglobinæmia have been, when typable, phenotypically Hp 2–1 or Hp 2–2, a strong association between the Hp 2 m –1 phenotype and haptoglobin depression exists in the American Negro 6 . We have studied an American Negro family, containing a pair of monozygotic twins in which hypohaptoglobinæmia unrelated to hæmolysis existed throughout an entire generation of offspring.