Chromosome 18: a possible site for a tumour suppressor gene deletion in squamous cell carcinoma of the head and neck.

The present study analyses tumour samples from 41 patients with squamous cell carcinoma of the head and neck (SCCHN) using the polymerase chain reaction (PCR) to detect genetic alterations on chromosome 18. Microsatellite markers were used to examine each sample for loss of heterozygosity (LOH) and microsatellite instability. Genetic alterations were most commonly noted on the long arm of chromosome 18 (18q). LOH/microsatellite instability occurred on 18q in 20/41 (49%) of patients. The highest single incidence of LOH was found at 18q21.1-21.3 using the microsatellite marker D18S35. LOH occurred in 10/30 (33%) informative cases while LOH/microsatellite instability occurred in 13/30 (43%) informative cases using this marker. Interestingly the tumour suppressor gene known as the 'deleted in colonic carcinoma' (DCC) gene is located in this region at 18q21.3 but is not commonly lost. This suggests that the marker D18S35 is mapping close to a second as yet unidentified tumour suppressor gene in this area.