The Impact of Genetic Counseling and Testing on one Family: A Case Report

Abstract

To describe a case which illustrates the importance of genetic counseling prior to pregnancy for individuals using IVF. Genetic counseling is provided for all couples at Zouves Fertility Center as part of their routine care. This case report illustrates the benefit of structuring IVF programs to include genetic counseling. Patient was seen for genetic counseling in October of 2004. She reported a family history of congenital retinoschisis in her identical twin sister’s 5 year old son. Her brother and 2 maternal uncles were also affected. Genetic counseling for this X-linked condition was provided. The patient is an obligate carrier since her identical twin has an affected child. No genetic testing had been performed in the family. The diagnosis was based on clnical findings. Without genetic test RESULTS on an affected individual in the family, PGD or prenatal diagnosis cannot be performed. The chance of transmitting the disease-causing mutation in each pregnancy is 50%. Male sibs who inherit the mutation will be affected; female sibs who inherit the mutation will be carriers who nearly always have normal visual function and normal electrophysiology. Affected males will pass the disease-causing mutation to all of their daughters and none of their sons. Genetic testing was arranged for the patient’s affected nephew. A mutation was identified by sequencing of the RS1 gene which involved a single base change (C to T). This test confirms the clinical diagnosis of X-linked retinoschisis. This is the mutation that the patient also carries by virtue of her position in the pedigree. The genetic test result enables this patient to take full advantage of PGD. This patient required IVF for reasons other than the family history of genetic disease. She had conducted research in the past to attempt to obtain genetic tesitng to no avail and was not aware that genetic testing was available for this condition. Had she been at a center where genetic counseling was not routinely provided as a routine part of care, she would have missed the opportunity to take advantage of genetic testing before pregnancy.