Methylation of the candidate biomarker TCF21 is very frequent across a spectrum of early-stage nonsmall cell lung cancers

Background: The transcription factor TCF21 is involved in mesenchymal-to-epithelial differentiation and was shown to be aberrantly hypermethylated in lung and head and neck cancers. Because of its reported high frequency of hypermethylation in lung cancer, further characterization of the stages and types of nonsmall cell lung cancer (NSCLC) that are hypermethylated and the frequency of hypermethylation and associated "second hits" were assessed. Methods: TCF21 promoter hypermethylation in 105 NSCLC including various stages and histologies in smokers and nonsmokers was determined. In addition, TCF21 loss of heterozygosity and mutational status were examined. Twenty-two cancer cell lines from varied tissue origins were also assayed. The NSCLC results were validated and expanded by examining TCF21 immunohistochemical expression on a tissue microarray containing 300 NSCLC cases. Results: Overall, 81% of NSCLC samples showed TCF21 promoter hypermethylation, and 84% showed decreased TCF21 protein expression. Multivariate analysis showed that TCF21 expression, although below normal in both histologies, was lower in adenocarcinoma than in squamous cell carcinoma and was not independently correlated with sex, smoking, and EGFR mutation status or with clinical outcome. Cell lines from other cancer types also showed frequent TCF21 promoter hypermethylation. Conclusions: Hypermethylation and decreased expression of TCF21 were tumor specific and very frequent in all NSCLCs, even early-stage disease, thus making TCF21 a potential candidate methylation biomarker for early-stage NSCLC screening. TCF21 hypermethylation in a variety of tumor cell lines suggests it may also be a valuable methylation biomarker in other tumor types. © 2010 American Cancer Society.link_to_subscribed_fulltex

Population frequency of myotonic dystrophy: higher than expected frequency of myotonic dystrophy type 2 (DM2) mutation in Finland

Myotonic dystrophy (DM) is the most common adult-onset muscular dystrophy with an estimated prevalence of 1/8000. There are two genetically distinct types, DM1 and DM2. DM2 is generally milder with more phenotypic variability than the classic DM1. Our previous data on co-segregation of heterozygous recessive CLCN1 mutations in DM2 patients indicated a higher than expected DM2 prevalence. The aim of this study was to determine the DM2 and DM1 frequency in the general population, and to explore whether the DM2 mutation functions as a modifier in other neuromuscular diseases (NMD) to account for unexplained phenotypic variability. We genotyped 5535 Finnish individuals: 4532 normal blood donors, 606 patients with various non-myotonic NMD, 221 tibial muscular dystrophy patients and their 176 healthy relatives for the DM2 and DM1 mutations. We also genotyped an Italian idiopathic non-myotonic proximal myopathy cohort (n=93) for the DM2 mutation. In 5496 samples analyzed for DM2, we found three DM2 mutations and two premutations. In 5511 samples analyzed for DM1, we found two DM1 mutations and two premutations. In the Italian cohort, we identified one patient with a DM2 mutation. We conclude that the DM2 mutation frequency is significantly higher in the general population (1/1830; P-value=0.0326) than previously estimated. The identification of DM2 mutations in NMD patients with clinical phenotypes not previously associated with DM2 is of particular interest and is in accord with the high overall prevalence. On the basis of our results, DM2 appears more frequent than DM1, with most DM2 patients currently undiagnosed with symptoms frequently occurring in the elderly population

Phenotypical spectrum of DOK7 mutations in congenital myasthenic syndromes.

Dok ('downstream-of-kinase') family of cytoplasmic proteins play a role in signalling downstream of receptor and non-receptor phosphotyrosine kinases. Recently, a skeletal muscle receptor tyrosine kinase (MuSK)-interacting cytoplasmic protein termed Dok-7 has been identified. Subsequently, we and others identified mutations in DOK7 as a cause of congenital myasthenic syndromes (CMS), providing evidence for a crucial role of Dok-7 in maintaining synaptic structure. Here we present clinical and molecular genetic data of 14 patients from 12 independent kinships with 13 different mutations in the DOK7 gene. The clinical picture of CMS with DOK7 mutations is highly variable. The age of onset may vary between birth and the third decade. However, most of the patients display a characteristic 'limb-girdle' pattern of weakness with a waddling gait and ptosis, but without ophthalmoparesis. Respiratory problems were frequent. Patients did not benefit from long-term therapy with esterase inhibitors; some of the patients even worsened. DOK7 mutations have emerged as one of the major genetic defects in CMS. The clinical picture differs significantly from CMS caused by mutations in other genes, such as the acetylcholine receptor (AChR) subunit genes. None of the patients with DOK7 mutations had tubular aggregates in the muscle biopsy, implying that 'limb-girdle myasthenia (LGM) with tubular aggregates' previously described in literature may be a pathogenic entity distinct from CMS caused by DOK7 mutations

Dutch myotonic dystrophy type 2 patients and a North-African DM2 family carry the common European founder haplotype

Myotonic dystrophy type 2 (DM2) is a progressive multisystem disease with muscle weakness and myotonia as main characteristics. The disease is caused by a repeat expansion in the zinc-finger protein 9 (ZNF9) gene on chromosome 3q21. Several reports show that patients from European ancestry share an identical haplotype surrounding the ZNF9 gene. In this study, we investigated whether the Dutch DM2 population carries the same founder haplotype. In all, 40 Dutch DM2 patients from 16 families were genotyped for eight short tandem repeat markers surrounding the ZNF9 gene. In addition, the single-nucleotide polymorphism (SNP) rs1871922 located in the first intron of DM2 was genotyped. Results were compared with previously published haplotypes from unrelated Caucasian patients. The repeat lengths identified in this study were in agreement with existing literature. In 36 patients of our population, we identified three common haplotypes. One patient showed overlap with the common haplotype for only one marker closest to the ZNF9 gene. The haplotype from a family originating from Morocco showed overlap with that of the patients of European descent for a region of 222 kb. All patients carried at least one C allele of SNP rs1871922 indicating that all patients carry the European founder haplotype. We conclude that DM2 patients from the Netherlands, including a North-African family, harbor a common haplotype surrounding the ZNF9 gene. This data show that the Dutch patients carry the common founder haplotype and strongly suggest that DM2 mutations in Europe and North Africa originate from a single ancestral founder