Detection of allelic imbalance in the gene expression of hMSH2 or RB1 in lymphocytes from pedigrees of hereditary, nonpolyposis, colorectal cancer and retinoblastoma by an RNA difference plot.

A number of phenotypes in hereditary disorders or common diseases are associated with specific genotypes. However, little is known about the molecular basis of phenotypic variation among individuals carrying the same mutation or polymorphism. Here, a highly quantitative approach was taken to examine a relative amount of mRNA from two polymorphic alleles with a coefficient of variation of less than 10% using an RNA difference plot (RDP).

Outpatient clinic for genetic counseling and gene testing of retinoblastoma.

We report on the genetic counseling and gene testing of patients with retinoblastoma who visited the National Cancer Center Hospital, Tokyo, from April 1997 through September 2003. During this period, 73 probands visited the clinic, and gene testing was performed in 51 individuals. Germline mutations of the RBI gene were detected in 20 individuals (39%); the frequencies were 82% (9/11) in bilateral/familial retinoblastoma, 50% (2/4) in unilateral/familial retinoblastoma, 50% (8/16) in bilateral/nonfamilial retinoblastoma, and 5% (1/20) in unilateral/nonfamilial retinoblastoma.