Incidental finding of a BRCA2 variant following whole genome sequencing to molecularly diagnose bilateral congenital cataracts.

A male patient in his 20s with a history of bilateral congenital cataracts and nystagmus presented to the genetic eye disease clinic at Moorfields Eye Hospital to enquire about genetic testing for family decision-making and access to preimplantation genetic testing. He had a history of lensectomy with best-corrected visual acuities of logMAR 0.60 and 1.00 in the right and left eye. Whole genome sequencing (WGS) was conducted, which included targeted analysis of a panel of 115 lens-related genes and incidental findings, for which patients are unable to opt-out. Genetic testing identified the causative variant c.134T>C (p.Leu45Pro) in the CRYGC gene. A pathogenic variant in BRCA2 was also identified as a secondary finding. This was unexpected given the absence of a strong family history of breast or ovarian cancer. This case illustrates the importance of genetic counselling and informing patients about the implications of incidental findings that arise from WGS.