Purine nucleoside phosphorylase deficiency; genetic studies in a Dutch family.

Abstract

Purine-nucleoside Phosphorylase (EC 2.4.2.1) catalyzes the phosphorolysis of (deoxy)inosine and (deoxy)guanosine. Patients deficient in purine nucleoside Phosphorylase (PNP) show disturbances in thymus-dependent immunity and have normal or nearly normal humoral immunity1–5. PNP deficiency is inherited as an autosomally recessive trait. The gene for PNP is located on chromosome 14. PNP appears to be a trimer with a molecular weight of 93 8006. The subunits of the enzyme from human erythrocytes have the same molecular weight but different isoelectric points6. Giblett et al.3 described a patient homozygous for PNP deficiency whose heterozygous parents exhibited an erythrocyte PNP with diminished activity and an altered electrophoretic mobility. Osborne et al.7 described one family in which two different variant alleles for PNP deficiency were present. We were able too to study a case of PNP deficiency5. In the Dutch family with PNP deficiency no PNP activity could be detected in the erythrocytes and lymphocytes of the patient, whereas the PNP activity of the erythrocytes of the father and mother showed one-half normal enzyme activity. The parents are unrelated. It may be possible that each parent has a different mutation. The purpose of this study is to describe more in detail the possible genetic heterogeneity of PNP deficiency in the Dutch family. The results reported here are highly indicative that only one mutant allele is present in this family.KeywordsMutant AllelePurine Nucleoside PhosphorylaseRecessive TraitHeterozygous ParentNormal EnzymeThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.