Birth of a healthy female after preimplantation genetic diagnosis for Charcot-Marie-Tooth type X

The X-linked dominant form of Charcot-Marie-Tooth syndrome (CMTX) is a clinically and genetically heterogeneous hereditary disorder of the peripheral nerves caused by mutations in the GJB1 gene that encodes a gap junction protein named connexin 32 (Cx32). Clinically, CMTX is characterized by peripheral motor and sensory deficit with muscle atrophy. A couple with a previous history of pregnancy termination after being diagnosed positive for CMTX by chorionic villus sampling, was referred for preimplantation genetic diagnosis (PGD). The female partner carried the causative H94Q, characterized by a C→G substitution in codon 94 of exon 2 of the GJB1 gene. Embryos obtained after intracytoplasmic sperm injection (ICSI) were evaluated for the presence of the mother's mutation using polymerase chain reaction (PCR), followed by mutation analysis performed using the minisequencing method. Amelogenin sequences on the X and Y chromosomes were also co-amplified to provide a correlation between embryo gender and mutation presence. A single PGD cycle was performed, involving nine fertilized oocytes, five of which developed into good quality embryos useful for biopsy. Two unaffected embryos were transferred, resulting in a singleton pregnancy followed by the birth of a healthy female.