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 diff erent regions of the N-myc gene demonstrated three polymorphic restric tion sites in the Indian population. The SphI and PvuII polymorphic pa ttern due to the SphI polymorphic site in the second intron and the Pv uII polymorphic site in the 3'-region of the human N-myc oncogene resp ectively, was similar to that reported in the Japanese population. The allelic frequency distribution for SphI polymorphism did not differ s ignificantly for the S1 and S2 alleles representing presence (allele S 1) or absence (allele S2) of a SphI site. However, the allelic frequen cy distribution was distorted in the case of PvuII polymorphism, as th e 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 t he 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, indica ting that this RFLP was not tumor associated and may perhaps represent N-myc alteration in the Indian population.