A 5'-truncated c-myc gene variant not associated with a risk of cancer.
By analyzing c-myc specific fragments from white blood cell DNAs of 98 gastric cancer patients and 46 control subjects, we observed 6 unexpected patterns due to presence of a variant c-myc gene in addition to the normal gene. Restriction enzyme mapping indicated that the variant c-myc gene was the result of a 5' deletion including the first exon and part of the first intron. The deleted region, non-coding for the functional c-myc protein, contains sequences involved in the regulation of transcription. We therefore analyzed the c-myc mRNAs from a subject carrying the truncated gene and from a subject homozygous for the normal gene in Northern blotting experiments: the mRNAs were indistinguishable, both qualitatively and quantitatively. Family analysis demonstrated that the truncated gene is inherited in a Mendelian fashion. Population studies showed that the allele, both in patients and in control subjects, reaches a polymorphic frequency (2.1% for the whole sample) and that it is not associated with a risk of cancer.
Department of Genetics and Microbiology, University of Pavia, Italy.
N S
NS
Pellegata
G
G
Bergamaschi
D
D
Amadori
A
A
Aloia
P
P
Ballarini
L
L
Del Senno
L
L
Amaducci
G N
GN
Ranzani
D015152:Blotting, Northern; D015139:Blotting, Southern; D002478:Cells, Cultured; D015246:Deoxyribonuclease EcoRI; D015870:Gene Expression; D016259:Genes, myc; D006801:Humans; D007558:Italy / Q000453:epidemiology; D009154:Mutation; D015183:Restriction Mapping; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000453:epidemiology / Q000235:genetics*
D015246:Deoxyribonuclease EcoRI