Yell Leaders & Yell Practice - 72

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Majority of hMLH1 mutations responsible for hereditary nonpolyposis colorectal cancer cluster at the exonic region 15-16

Hereditary nonpolyposis colorectal cancer (HNPCC) is a common autosomal dominant cancer susceptibility condition. Inherited mutations in at least four DNA mismatch repair genes, hMSH2, hMLH1, hPMS1, and hPMS2, are known to cause HNPCC. In this study we used denaturing gradient gel electrophoresis (DGGE) to screen for hMLH1 mutations in 34 unrelated HNPCC families (30 Dutch, 3 Italian, and 1 Danish). Ten novel pathogenic germ-line mutations (seven affecting splice sites, two frameshifts, and one in-frame deletion of a single amino acid) have been identified in 12 (35%) of these families. In a previous study, hMSH2 mutations were found in 21% of the same families. While the spectrum of mutations at the hMSH2 gene among HNPCC patients appears heterogeneous, a cluster of hMLH1 mutations has been found in the region encompassing exons 15 and 16, which accounts for 50% of all the independent hMLH1 mutations described to date and for >20% of the unrelated HNPCC kindreds here analyzed. This unexpected finding has a great practical value in the clinical scenario of genetic services

Psychological distress in applicants for predictive DNA testing for autosomal dominant, heritable, late onset disorders

In a comparative study on the effects of predictive DNA testing for late onset disorders, pre-test psychological distress was assessed in people at risk for Huntington's disease (HD, n=41), cerebral haemorrhage (HCHWA-D, n=9), breast and ovarian cancer (HBOC, n=24), and polyposis coli (FAP, n=45). Partners, if available, also participated in the study, Distress was measured with the subscales Intrusion and Avoidance of the Impact of Event Scale. People at risk for the neurodegenerative disorders reported more avoidance than those at risk for the cancer syndromes. People at risk for FAP and partners of those at risk for HBOC reported less intrusion than the others at risk and the other partners. Subjects who were more distressed reported more experiences with the disease in close relatives, the disease having a great impact on their lives, having considerations against predictive testing, expecting that being identified as a gene carrier would have adverse effects, and expecting relief after being identified as a non-carrier. Test candidates who expected an increase of personal problems showed higher avoidance, whereas those who could better anticipate future life as a carrier had higher intrusion levels. Generally, subjects with high distress levels are of more concern to the healthcare professional than those with low distress levels. However, high distress may reflect worrying as a mental preparation for the test result, whereas low distress may indicate denial-avoidance behaviour and poor anticipation of the test outcome. In pre-test counselling sessions, this should be acknowledged and addressed

Psychological distress in applicants for predictive DNA testing for autosomal dominant, heritable, late onset disorders

In a comparative study on the effects of predictive DNA testing for late onset disorders, pre-test psychological distress was assessed in people at risk for Huntington's disease (HD, n=41), cerebral haemorrhage (HCHWA-D, n=9), breast and ovarian cancer (HBOC, n=24), and polyposis coli (FAP, n=45). Partners, if available, also participated in the study, Distress was measured with the subscales Intrusion and Avoidance of the Impact of Event Scale. People at risk for the neurodegenerative disorders reported more avoidance than those at risk for the cancer syndromes. People at risk for FAP and partners of those at risk for HBOC reported less intrusion than the others at risk and the other partners. Subjects who were more distressed reported more experiences with the disease in close relatives, the disease having a great impact on their lives, having considerations against predictive testing, expecting that being identified as a gene carrier would have adverse effects, and expecting relief after being identified as a non-carrier. Test candidates who expected an increase of personal problems showed higher avoidance, whereas those who could better anticipate future life as a carrier had higher intrusion levels. Generally, subjects with high distress levels are of more concern to the healthcare professional than those with low distress levels. However, high distress may reflect worrying as a mental preparation for the test result, whereas low distress may indicate denial-avoidance behaviour and poor anticipation of the test outcome. In pre-test counselling sessions, this should be acknowledged and addressed