Defective C-propeptides of the proalpha2(I) chain of type I procollagen impede molecular assembly and result in osteogenesis imperfecta.

Type I procollagen is a heterotrimer composed of two proalpha1(I) chains and one proalpha2(I) chain, encoded by the COL1A1 and COL1A2 genes, respectively. Mutations in these genes usually lead to dominantly inherited forms of osteogenesis imperfecta (OI) by altering the triple helical domains, but a few affect sequences in the proalpha1(I) C-terminal propeptide (C-propeptide), and one, which has a phenotype only in homozygotes, alters the proalpha2(I) C-propeptide. Here we describe four dominant mutations in the COL1A2 gene that alter sequences of the proalpha2(I) C-propeptide in individuals with clinical features of a milder form of the disease, OI type IV.

Hypermethylation of the TPEF/HPP1 gene in primary and metastatic colorectal cancers.

The role of promoter methylation in the process of cancer cell metastasis has, however, not yet been studied. Recently, methylation of the TPEF (transmembrane protein containing epidermal growth factor and follistatin domain) gene was reported in human colon, gastric, and bladder cancer cells. Using the Methylight assay, TPEF/HPP1 gene methylation was assessed in primary colorectal cancers (n = 47), matched normal colon mucosa, as well as in the liver metastasis of 24 patients with colorectal cancer, and compared to the methylation status of the TIMP-3, APC, DAPK, caveolin-2, and p16 genes.

A real-time PCR assay for DNA-methylation using methylation-specific blockers.

DNA methylation-based biomarkers have been discovered that could potentially be used for the diagnosis of cancer by detection of circulating, tumor-derived DNA in bodily fluids. Any methylation detection assay that would be applied to these samples must be capable of detecting small amounts of tumor DNA in the presence of background normal DNA. We have developed a real-time PCR assay, called HeavyMethyl, that is well suited for this application.