Preimplantation genetic diagnosis in prevention of genetic diseases – diagnostic of spinal muscular atrophy (SMA)

Abstract

Summary Introduction: Preimplantation genetic diagnosis, PGD, is an established procedure allowing genetic research of the oocyte or embryo before implantation to the uterus. A neurodegenerative disorder known as spinal muscular atrophy (SMA) is the second most common lethal autosomal recessive disease in Caucasians, after cystic fibrosis. There are three clinically different types of the disease, with type I (Werding-Hoffman Disease) being the most severe. Around 98% of clinical cases of SMA are caused by the homozygous absence of a region of exons 7 and 8 of the telomeric copy of the SMN gene (SMN1) on chromosome 5 (5q13.3). Objectives: The aim of the present work was to performed PGD for SMA in 5 couples who had already had a child affected with SMA. Material and Methods: All patients underwent a standard IVF procedure associated with intracytoplasmic sperm injection. 6-8 cell embryos were biopsied on day 3 of culture. Single cell nested PCR-RFLP protocol for PGD of SMA was used for the detection of the mutation. Results: In the course of IVF-PGD procedures all patients had a transfer of embryos without SMN1 deletions. Four out of the five couples delivered healthy babies. Conclusions: Preimplantation genetic diagnosis (PGD) of monogenic disorders is a very efficient method, especially for patients whose previous child is homozygous for genetic disorders. It offers new possibilities for the treatment for genetic disease carriers.