title: Evaluation of fetal nuchal translucency in 98 pregnancies at risk for severe spinal muscular atrophy: possible relevance of the SMN2 copy number.
abstract: OBJECTIVE
  To study fetal nuchal translucency (NT) thickness as a possible early marker in fetuses at risk for severe spinal muscular atrophy (SMA). To investigate the significance of the survival motor neuron (SMN) 2 gene copy number in affected fetuses.
  
  
  METHODS
  We performed 2D-ultrasound in 98 pregnancies at risk for SMA, all of which underwent prenatal molecular testing of the SMN1 gene. Crown-rump length (CRL) and NT measurements were obtained in all cases before chorionic villus sampling. Fetuses were diagnosed as healthy, carriers or affected according to the SMN1 molecular testing results. SMN2 copies were also tested in all affected fetuses.
  
  
  RESULTS
  Nineteen fetuses were predicted to be affected due to the absence of the SMN1 gene, 18 of which had two SMN2 copies. Mean CRL and NT values did not differ between healthy, carrier and affected fetuses. In the remaining affected case who had only one SMN2 copy, the ultrasound examination showed a NT value of 4.98 mm and findings compatible with hypoplastic left heart.
  
  
  CONCLUSIONS
  Most affected SMA fetuses have normal NT values. Our findings support the idea that SMN2 copy number in SMA fetuses is relevant for the development of congenital heart defects and increased NT values.
authors.affiliation: Department of Obstetrics and Gynecology, Hospital Sant Pau, Universitat Autonoma de Barcelona, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Parra
authors.forename: Laura
authors.initials: L
authors.lastname: Alias
authors.forename: Eva
authors.initials: E
authors.lastname: Also-Rallo
authors.forename: Rebeca
authors.initials: R
authors.lastname: Martínez-Hernández
authors.forename: Raquel
authors.initials: R
authors.lastname: Senosiain
authors.forename: Carmen
authors.initials: C
authors.lastname: Medina
authors.forename: Obdulia
authors.initials: O
authors.lastname: Alejos
authors.forename: Noelia
authors.initials: N
authors.lastname: Rams
authors.forename: María
authors.initials: M
authors.lastname: Amenedo
authors.forename: Filomena
authors.initials: F
authors.lastname: Ormo
authors.forename: María
authors.initials: M
authors.lastname: Jesús Barceló
authors.forename: Joaquim
authors.initials: J
authors.lastname: Calaf
authors.forename: Montserrat
authors.initials: M
authors.lastname: Baiget
authors.forename: Sara
authors.initials: S
authors.lastname: Bernal
authors.forename: Eduardo F
authors.initials: EF
authors.lastname: Tizzano
mesh_terms: D015331:Cohort Studies; D018568:Crown-Rump Length; D005260:Female; D018628:Gene Dosage / Q000502:physiology; D020022:Genetic Predisposition to Disease; D005820:Genetic Testing / Q000379:methods / Q000706:statistics & numerical data; D006801:Humans; D009134:Muscular Atrophy, Spinal / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000235:genetics*; D048208:Nuchal Translucency Measurement / Q000706:statistics & numerical data; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods; D012307:Risk Factors; D012720:Severity of Illness Index; D055540:Survival of Motor Neuron 2 Protein / Q000235:genetics
chemical_list: C526477:SMN2 protein, human; D055540:Survival of Motor Neuron 2 Protein