title: SMN1 and SMN2 copy numbers in cell lines derived from patients with spinal muscular atrophy as measured by array digital PCR.
abstract: Proximal spinal muscular atrophy (SMA) is an early-onset motor neuron disease characterized by loss of α-motor neurons and associated muscle atrophy. SMA is caused by deletion or other disabling mutation of survival motor neuron 1 (SMN1). In the human genome, a large duplication of the SMN-containing region gives rise to a second copy of this gene (SMN2) that is distinguishable by a single nucleotide change in exon 7. Within the SMA population, there is substantial variation in SMN2 copy number; in general, those individuals with SMA who have a high SMN2 copy number have a milder disease. Because SMN2 functions as a disease modifier, its accurate copy number determination may have clinical relevance. In this study, we describe the development of an assay to assess SMN1 and SMN2 copy numbers in DNA samples using an array-based digital PCR (dPCR) system. This dPCR assay can accurately and reliably measure the number of SMN1 and SMN2 copies in DNA samples. In a cohort of SMA patient-derived cell lines, the assay confirmed a strong inverse correlation between SMN2 copy number and disease severity. Array dPCR is a practical technique to determine, accurately and reliably, SMN1 and SMN2 copy numbers from SMA samples.
authors.affiliation: Nemours Biomolecular Core Laboratory, Nemours Biomedical Research, Nemours Alfred I. duPont Hospital for Children Wilmington, Delaware.
authors.forename: Deborah L
authors.initials: DL
authors.lastname: Stabley
authors.affiliation: Center for Applied Clinical Genomics, Nemours Biomedical Research, Nemours Alfred I. duPont Hospital for Children Wilmington, Delaware.
authors.forename: Ashlee W
authors.initials: AW
authors.lastname: Harris
authors.affiliation: Nemours Biomolecular Core Laboratory, Nemours Biomedical Research, Nemours Alfred I. duPont Hospital for Children Wilmington, Delaware.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Holbrook
authors.affiliation: Department of Biological Sciences, University of Delaware Newark, Delaware.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Chubbs
authors.affiliation: Department of Biological Sciences, University of Delaware Newark, Delaware.
authors.forename: Kevin W
authors.initials: KW
authors.lastname: Lozo
authors.affiliation: Department of Neurology, Johns Hopkins University Baltimore, Maryland ; Department of Pediatrics, Johns Hopkins University Baltimore, Maryland.
authors.forename: Thomas O
authors.initials: TO
authors.lastname: Crawford
authors.affiliation: Neurogenetics Research Program, Center for Human Genetics Research, Massachusetts General Hospital Boston, Massachusetts.
authors.forename: Kathryn J
authors.initials: KJ
authors.lastname: Swoboda
authors.affiliation: Center for Applied Clinical Genomics, Nemours Biomedical Research, Nemours Alfred I. duPont Hospital for Children Wilmington, Delaware ; Center for Pediatric Research, Nemours Biomedical Research, Nemours Alfred I. duPont Hospital for Children Wilmington, Delaware ; Department of Pediatrics, Thomas Jefferson University Philadelphia, Pennsylvania.
authors.forename: Vicky L
authors.initials: VL
authors.lastname: Funanage
authors.affiliation: Center for Applied Clinical Genomics, Nemours Biomedical Research, Nemours Alfred I. duPont Hospital for Children Wilmington, Delaware ; Center for Pediatric Research, Nemours Biomedical Research, Nemours Alfred I. duPont Hospital for Children Wilmington, Delaware ; Department of Pediatrics, Thomas Jefferson University Philadelphia, Pennsylvania.
authors.forename: Wenlan
authors.initials: W
authors.lastname: Wang
authors.affiliation: Division of Orthopedics, Nemours Alfred I. duPont Hospital for Children Wilmington, Delaware.
authors.forename: William
authors.initials: W
authors.lastname: Mackenzie
authors.affiliation: Division of Neurology, Nemours Alfred I. duPont Hospital for Children Wilmington, Delaware.
authors.forename: Mena
authors.initials: M
authors.lastname: Scavina
authors.affiliation: Nemours Biomolecular Core Laboratory, Nemours Biomedical Research, Nemours Alfred I. duPont Hospital for Children Wilmington, Delaware.
authors.forename: Katia
authors.initials: K
authors.lastname: Sol-Church
authors.affiliation: Center for Applied Clinical Genomics, Nemours Biomedical Research, Nemours Alfred I. duPont Hospital for Children Wilmington, Delaware ; Department of Biological Sciences, University of Delaware Newark, Delaware ; Center for Pediatric Research, Nemours Biomedical Research, Nemours Alfred I. duPont Hospital for Children Wilmington, Delaware ; Department of Pediatrics, Thomas Jefferson University Philadelphia, Pennsylvania.
authors.forename: Matthew E R
authors.initials: ME
authors.lastname: Butchbach
keywords: Array digital PCR; SMN1; SMN2; copy number; copy number variation; spinal muscular atrophy