title: Prenatal onset spinal muscular atrophy.
abstract: Five patients with severe spinal muscular atrophy (SMA) type I, all of whom presented with reduced fetal movements in utero, severe weakness at birth, and short survival time were assessed to attempt to determine whether their phenotype could be explained by their genotype. The diagnosis was confirmed by clinical, electrophysiological and histopathological features. Polymerase chain reaction assays were used to define the molecular diagnosis. A gene-dosage assay was used to assess the quantity of centromeric survival motor neuron gene (SMNc) present. In all cases the telomeric survival motor neuron gene (SMNt) was absent. The SMNc gene was present but in reduced copy number compared with a control group of children with less severe type I SMA, so may be important in determining severity. In the differential diagnosis of reduced fetal movements, SMA should be considered. The clinical classification may in future be clarified by molecular genetic findings.
authors.affiliation: Department of Paediatric Neurology, Guy's Hospital, St Thomas Street, London, SE1 9RT, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: MacLeod
authors.forename: J E
authors.initials: JE
authors.lastname: Taylor
authors.forename: P W
authors.initials: PW
authors.lastname: Lunt
authors.forename: C G
authors.initials: CG
authors.lastname: Mathew
authors.forename: S A
authors.initials: SA
authors.lastname: Robb
mesh_terms: D002470:Cell Survival / Q000235:genetics; D002503:Centromere / Q000235:genetics; D002895:Chromosomes, Human, Pair 5; D005260:Female; D005324:Fetal Movement / Q000235:genetics; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009046:Motor Neurons / Q000473:pathology; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011296:Prenatal Diagnosis; D014897:Spinal Muscular Atrophies of Childhood / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D016615:Telomere / Q000235:genetics