title: Preimplantation genetic diagnosis of Canavan disease.
abstract: OBJECTIVE
  Canavan disease is an autosomal recessive disorder which is relatively common in Ashkenazi Jews. It is characterized by developmental delay, severe hypotonia and early death, and is caused by a deficiency of aspartoacylase which is encoded by the ASPA gene. In Ashkenazi Jews, one major mutation (E285A) and one minor mutation (Y231X) account for the majority of cases. The objective of this study was to develop a preimplantation genetic diagnosis (PGD) protocol for Canavan disease.
  
  
  METHODS
  Two carrier couples requested PGD for Canavan disease. In 1 couple each was a carrier of a different ASPA mutation (Y231X and E285A). In the other couple both were carriers of the minor mutation (Y231X). A single-cell duplex nested polymerase chain reaction (PCR) protocol was first developed on single leukocytes obtained from the known carrier parents. Following verification in single leukocytes, clinical PGD was offered to both couples.
  
  
  RESULTS
  We evaluated 115 single leukocytes from known carriers and found an allele drop out rate of 1.7% for the fragment harboring the Y231X mutation and 0% for the fragment harboring the E285A mutation. One cycle of PGD was performed in each family. In the first, 11 embryos were successfully analyzed and 4 were found to be affected. Two unaffected embryos were transferred, but no pregnancy resulted. In the other family, 4 embryos were analyzed, 1 was affected, 2 were heterozygotes and 1 was homozygous normal. Following transfer of 2 unaffected embryos, a singleton pregnancy resulted, currently ongoing at 18 weeks gestational age. Amniocentesis performed at 16 weeks confirmed the diagnosis.
  
  
  CONCLUSIONS
  Reliable PGD for Canavan disease is possible using a single-cell nested PCR approach.
authors.affiliation: Prenatal Diagnosis Unit, Genetic Institute, Sourasky Medical Center, Tel Aviv, Israel. yyaron@tasmc.health.gov.il
authors.forename: Yuval
authors.initials: Y
authors.lastname: Yaron
authors.forename: Tamar
authors.initials: T
authors.lastname: Schwartz
authors.forename: Nava
authors.initials: N
authors.lastname: Mey-Raz
authors.forename: Ami
authors.initials: A
authors.lastname: Amit
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Lessing
authors.forename: Mira
authors.initials: M
authors.lastname: Malcov
mesh_terms: D017825:Canavan Disease / Q000175:diagnosis* / Q000235:genetics*; D005260:Female; D005820:Genetic Testing / Q000379:methods* / Q000592:standards; D006801:Humans; D007585:Jews / Q000235:genetics; D007962:Leukocytes; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D019836:Preimplantation Diagnosis / Q000379:methods* / Q000592:standards; D015203:Reproducibility of Results