title: Human SP-A locus: allele frequencies and linkage disequilibrium between the two surfactant protein A genes.
abstract: Two surfactant protein A (SP-A) genes and several alleles for each SP-A locus have been previously described. In this report we investigate the potential usefulness of the SP-A loci as markers for genetic studies. We establish conditions that allow the identification of alleles with very similar sequences; We also determine the degree of polymorphism for each SP-A locus: The heterozygosity and polymorphism information content (PIC) values for the SP-A1 locus are 0.63 and 0.55, respectively, and for the SP-A2 locus are 0.50 and 0.56. In the course of these studies, we identify one new SP-A2 allele and show that the SP-A1 and SP-A2 loci are in linkage disequilibrium (P < 0.000001). We also identify 19 of the 20 possible haplotypes in a population of n = 239. Nine of the observed haplotypes reach statistical significance (P < 0.01) in this population, and the segregation of two haplotypes (6A2/1A0 and 6A4/1A) without recombination is verified in a family pedigree. These data together indicate that both SP-A loci are sufficiently polymorphic to be good markers for use in genetic studies. Furthermore, the finding of one novel allele suggests that additional unknown SP-A alleles are yet to be found.
authors.affiliation: Department of Cellular and Molecular Physiology, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, Hershey, 17033-0850, USA.
authors.forename: J
authors.initials: J
authors.lastname: Floros
authors.forename: S
authors.initials: S
authors.lastname: DiAngelo
authors.forename: M
authors.initials: M
authors.lastname: Koptides
authors.forename: A M
authors.initials: AM
authors.lastname: Karinch
authors.forename: P K
authors.initials: PK
authors.lastname: Rogan
authors.forename: H
authors.initials: H
authors.lastname: Nielsen
authors.forename: R G
authors.initials: RG
authors.lastname: Spragg
authors.forename: K
authors.initials: K
authors.lastname: Watterberg
authors.forename: G
authors.initials: G
authors.lastname: Deiter
mesh_terms: D000328:Adult; D000483:Alleles; D015415:Biomarkers; D005787:Gene Frequency; D008040:Genetic Linkage; D006801:Humans; D007231:Infant, Newborn; D010375:Pedigree; D011110:Polymorphism, Genetic; D011510:Proteolipids / Q000235:genetics*; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000235:genetics*
chemical_list: D015415:Biomarkers; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; C445842:SFTPA1 protein, human; C445843:SFTPA2 protein, human