DNA resequencing array for mutation detection in hypertrophic cardiomyopathy

Objectives: Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac disease. Clinical presentation is heterogeneous, outcome ranging from benign asymptomatic forms to more malignant expressions resulting in sudden or heart failure death. To date, more than 450 mutations have been reported in 11 genes encoding sarcomeric proteins, in 3 genes encoding proteins of the z-disc, in 2 genes involved in cardiac metabolism and in 1 gene encoding a protein of the intercalated discs. DNA testing is very helpful for diagnosis, prognosis or predictive testing, however, by classical methods, mutation screening in HCM remains expensive and time-consuming. In the past few years, a DNA-resequencing array was developed for mutation detection in HCM. Methods: The 30 kb-DNA-resequencing-array covers all coding exons (161), splice-site junctions and known promoter regions of the 12 genes most frequently involved in HCM. It is able to detect single nucleotide substitutions (which account for up to 86% of all HCM mutations), but actually it does not detect small deletions and insertions. Results: We analyzed a series of 35 HCM patients (age: 39±15 years; 21 males, 60%; 28 familial cases, 80%; 16 with obstruction, 46%) enrolled at a tertiary Center. We succeeded in identifying 15 different functional single nucleotide substitutions in 18 patients (51%) in the genes MYBPC3, MYH7, TNNT2, TNNI3 and MYL3. Four functional variants were known missense mutations found in 4 patients. Five were novel functional changes, which were not found in a control series of 300 chromosomes. Furthermore we identified 6 known SNPs whereas three of them were previously reported in HGMD as mutation or risk factor for HCM. Conclusions: Presently DNA resequencing array appears as the most rapid and cost-effective technology for mutation screening in HCM. Further improvement of the software may detect small insertions/deletions. The resequencing array provides a first attempt of high throughput sequencing methodology which will further develop and probably become the method of choice for routine molecular diagnosis of heterogeneous disorders such as HCM.