title: High-density single nucleotide polymorphism screen in a large multiplex neural tube defect family refines linkage to loci at 7p21.1-pter and 2q33.1-q35.
abstract: BACKGROUND
  Neural tube defects (NTDs) are considered complex, with both genetic and environmental factors implicated. To date, no major causative genes have been identified in humans despite several investigations. The first genomewide screen in NTDs demonstrated evidence of linkage to chromosomes 7 and 10. This screen included 44 multiplex families and consisted of 402 microsatellite markers spaced approximately 10 cM apart. Further investigation of the genomic screen data identified a single large multiplex family, pedigree 8776, as primarily driving the linkage results on chromosome 7.
  
  
  METHODS
  To investigate this family more thoroughly, a high-density single nucleotide polymorphism (SNP) screen was performed. Two-point and multipoint linkage analyses were performed using both parametric and nonparametric methods.
  
  
  RESULTS
  For both the microsatellite and SNP markers, linkage analysis suggested the involvement of a locus or loci proximal to the telomeric regions of chromosomes 2q and 7p, with both regions generating a LOD* score of 3.0 using a nonparametric identity by descent relative sharing method.
  
  
  CONCLUSIONS
  The regions with the strongest evidence for linkage map proximal to the telomeres on these two chromosomes. In addition to mutations and/or variants in a major gene, these loci may harbor a microdeletion and/or translocation; potentially, polygenic factors may also be involved. This single family may be promising for narrowing the search for NTD susceptibility genes.
authors.affiliation: Center for Human Genetics, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Demetra S
authors.initials: DS
authors.lastname: Stamm
authors.forename: Evadnie
authors.initials: E
authors.lastname: Rampersaud
authors.forename: Susan H
authors.initials: SH
authors.lastname: Slifer
authors.forename: Lorraine
authors.initials: L
authors.lastname: Mehltretter
authors.forename: Deborah G
authors.initials: DG
authors.lastname: Siegel
authors.forename: Jianzhen
authors.initials: J
authors.lastname: Xie
authors.forename: Diane
authors.initials: D
authors.lastname: Hu-Lince
authors.forename: David W
authors.initials: DW
authors.lastname: Craig
authors.forename: Dietrich A
authors.initials: DA
authors.lastname: Stephan
authors.forename: Timothy M
authors.initials: TM
authors.lastname: George
authors.forename: John R
authors.initials: JR
authors.lastname: Gilbert
authors.forename: Marcy C
authors.initials: MC
authors.lastname: Speer
mesh_terms: D002889:Chromosomes, Human, Pair 2 / Q000235:genetics*; D002897:Chromosomes, Human, Pair 7 / Q000235:genetics*; D005260:Female; D008040:Genetic Linkage; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D009436:Neural Tube Defects / Q000235:genetics*; D010375:Pedigree; D020641:Polymorphism, Single Nucleotide