Haplotypes were established for the alleles at the EcoRI and BamHI polymorphic restriction sites associated with the human somatostatin (SST) gene. The two genetic markers, in spite of their proximity, are in linkage equilibrium.

S-adenosylhomocysteine hydrolase (SAHH) polymorphism has been investigated in the Italian population. Three common alleles, SAHH*1, SAHH*2 and SAHH*3, have been observed and the estimated gene frequencies are 0.968, 0.023 and 0.009, respectively. SAHH activity has been assayed in 50 healthy individuals and the mean activity was 0.043 ± 0.017 µmol uric acid/min/g Hb at 37 °C. Five heterozygotes for adenosine deaminase deficiency and three heterozygotes for purine nucleoside phosphorylase deficiency showed SAHH within the range of the normal distribution. The effects of some thiol reagents on red blood cell SAHH electrophoretic pattern have been investigated.