abstract: Follow-up of carriers of BRCA1 and BRCA2 variants of unknown significance: variant reclassification and surgical decisions.

Blogger's Note: while this article is specific to BRCA 1/2 it also would apply to other genetic syndromes eg. Lynch Syndrome, Peutz-Jeghers 
             ~~~~~~~~~~~~~~~

Follow-up of carriers of BRCA1 and BRCA2 variants of unknown significance: variant reclassification and surgical decisions.:


Genet Med. 2011 Dec;13(12):998-1005

Abstract
PURPOSE:
Approximately 5-10% of patients who undergo genetic testing of BRCA1 and BRCA2 receive a variant of unknown significance (VUS) result. The ambiguous nature of a VUS may increase difficulty in patient understanding and decision making regarding risk reduction and surveillance options, including cancer risk-reducing surgeries. VUS reclassification to benign or deleterious may occur in time; however, clinical decisions may need to be made expeditiously, and some patients may pursue irreversible treatments before VUS reclassification.

METHODS:
We reviewed the surgical decisions of 107 women postdisclosure of a BRCA VUS result counseled at our institute between 1998 and 2009.

CONCLUSION:
Among women receiving a BRCA VUS result at our center, 11 of 107 (10.3%) pursued cancer risk-reducing mastectomy and 22 of 107 (20.6%) pursued cancer risk-reducing bilateral salpingo-oophorectomy. Reclassification of VUS occurred up to 9 years after testing, and 5 of 22 (22.7%) women followed up for 8 or more years continue to have a VUS result. We discuss considerations for providers of genetic services to discuss with patients who receive a VUS result.

abstract: Familial Cancer, A putative Lynch syndrome family carrying MSH2 and MSH6 variants of uncertain significance—functional analysis reveals the pathological one

Abstract

Inherited pathogenic mutations in the mismatch repair (MMR) genes, MSH2, MLH1, MSH6, and PMS2 predispose to Lynch syndrome (LS). However, the finding of a variant or variants of uncertain significance (VUS) in affected family members complicates the risk assessment. Here, we describe a putative LS family carrying VUS in both MSH2 (c.2768T>A, p.Val923Glu) and MSH6 (c.3563G>A, p.Ser1188Asn). Two colorectal cancer (CRC) patients were studied for mutations and identified as carriers of both variants. In spite of a relatively high mean age of cancer onset (59.5 years) in the family, many CRC patients and the tumor pathological data suggested that the missense variation in MSH2, the more common susceptibility gene in LS, would be the predisposing alteration. However, MSH2 VUS was surprisingly found to be MMR proficient in an in vitro MMR assay and a tolerant alteration in silico. By supplying evidence that instead of MSH2 p.Val923Glu the MSH6 p.Ser1188Asn variant is completely MMR-deficient, the present study confirms the previous findings, and suggests that MSH6 (c.3563G>A, p.Ser1188Asn) is the pathogenic mutation in the family. Moreover, our results strongly support the strategy to functionally assess all identified VUS before predictive gene testing and genetic counseling are offered to a family.