Restriction fragment length polymorphisms of the human N-myc gene in normal healthy individuals and oral cancer patients in India.

Southern blot hybridization with N-myc oncogene probes coding for different regions of the N-myc gene demonstrated three polymorphic restriction sites in the Indian population. The SphI and PvuII polymorphic pattern due to the SphI polymorphic site in the second intron and the PvuII polymorphic site in the 3'-region of the human N-myc oncogene respectively, was similar to that reported in the Japanese population. The allelic frequency distribution for SphI polymorphism did not differ significantly for the S1 and S2 alleles representing presence (allele S1) or absence (allele S2) of a SphI site. However, the allelic frequency distribution was distorted in the case of PvuII polymorphism, as the frequency of P1 allele (0.7) indicating presence of PvuII site, was higher than the P2 allele (0.3) indicating absence of PvuII site, in the Indian population. An additional polymorphic HindIII site localised in the second intron of the N-myc gene was also observed in both the Indian oral cancer patients and the normal healthy individuals, indicating that this RFLP was not tumor associated and may perhaps represent N-myc alteration in the Indian population.