Multiplex ligation-dependent probe amplification (MLPA) enhances the molecular diagnosis of aniridia and related disorders

Mutations in the PAX6 gene have been implicated in aniridia, a congenital malformation of the eye with severe hypoplasia of the iris. However, not all aniridia cases can be explained by mutations in the PAX6 gene. The purpose of this study was to enhance the molecular diagnosis of aniridia using multiplex ligation-dependent probe amplification (MLPA). Total genomic DNA was isolated from peripheral blood of 70 unrelated probands affected with aniridia. Polymerase chain reaction (PCR) was performed followed by automated bidirectional sequencing. Additionally, MLPA was performed. We identified 24 different point mutations in the PAX6 gene in 34 patients after sequencing. In eight additional patients, we identified a deletion of one or more exons of the PAX6 gene or in the 3′ regulatory region of the PAX6 gene using MLPA. This work demonstrates the necessity to screen for larger deletions in the region of the PAX6 gene in addition to the sequencing of exons in the PAX6 gene. The mutation detection rate will increase from 49% to 60%. This shows that MLPA substantially enhances the molecular diagnosis of aniridia

Cancer Risks for PMS2-associated lynch syndrom

Lynch syndrome due to pathogenic variants in the DNA mismatch repair genes MLH1, MSH2, and MSH6 is predominantly associated with colorectal and endometrial cancer, although extracolonic cancers have been described within the Lynch tumor spectrum. However, the age-specific cumulative risk (penetrance) of these cancers is still poorly defined for PMS2-associated Lynch syndrome. Using a large data set from a worldwide collaboration, our aim was to determine accurate penetrance measures of cancers for carriers of heterozygous pathogenic PMS2 variants. Methods A modified segregation analysis was conducted that incorporated both genotyped and nongenotyped relatives, with conditioning for ascertainment to estimates corrected for bias. Hazard ratios (HRs) and corresponding 95% CIs were estimated for each cancer site for mutation carriers compared with the general population, followed by estimation of penetrance. Results In total, 284 families consisting of 4,878 first- A nd second-degree family members were included in the analysis. PMS2 mutation carriers were at increased risk for colorectal cancer (cumulative risk to age 80 years of 13% [95% CI, 7.9% to 22%] for males and 12% [95% CI, 6.7% to 21%] for females) and endometrial cancer (13% [95% CI, 7.0%-24%]), compared with the general population (6.6%, 4.7%, and 2.4%, respectively). There was no clear evidence of an increased risk of ovarian, gastric, hepatobiliary, bladder, renal, brain, breast, prostate, or small bowel cancer. Conclusion Heterozygous PMS2 mutation carriers were at small increased risk for colorectal and endometrial cancer but not for any other Lynch syndrome-associated cancer. This finding justifies that PMS2-specific screening protocols could be restricted to colonoscopies. The role of risk-reducing hysterectomy and bilateral salpingo-oophorectomy for PMS2 mutation carriers needs further discussion