24. Tay-Sachs disease and preimplantation genetic diagnosis

Publisher Summary This chapter discusses the Tay-Sachs disease (TSD) and Preimplantation Genetic Diagnosis in detail. TSD is an autosomal recessive progressive neurodegenerative disorder which is characterized by a deficiency of the enzyme Hexosaminidase A. Clinical features includes developmental retardation, paralysis, dementia, and blindness. The diagnosis of TSD is based on both DNA (deoxyribonucleic acid) and enzymatic testing, including prenatal testing. The most severe problem of enzymatic testing is the high frequency of false positive results. DNA testing may suffer from false negative results due to many rare alleles. Genetic testing of the parents can be done in several ways, including allele-specific oligonucleotide hybridization (ASO), single-cell whole-genome pre-amplification, or heteroduplex polymerase chain reaction (PCR) fragment analysis. Preimplantation genetic diagnosis (PGD) is an excellent tool to prevent a future child from suffering with a severe disease. TSD is a very likely candidate for PGD and provides excellent reasons to test the embryo. Diagnosis can be confirmed by amniocentesis or chorionic villus sampling.