Mild Cystic Fibrosis Linked to Chromosome 7q22 Markers with an Uncommon Haplotype

  1. Allyn McConkie-Rosell, MSW;
  2. Yuan-Tsong Chen, MD, PhD;
  3. Denise Harris;
  4. Marcy C. Speer, MS;
  5. Margaret A. Pericak-Vance, PhD;
  6. Jia-Huan Ding, MD, PhD;
  7. W. Edward Highsmith, Jr., PhD;
  8. Michael Knowles, MD; and
  9. Stephen G. Kahler, MD

    Abstract

    Cystic fibrosis is the commonest autosomal recessive genetic disorder among northern Europeans and their descendants. Recently, investigators have mapped the gene for cystic fibrosis to chromosome 7. We report the results of DNA linkage analysis in a consanguineous family with mild cystic fibrosis. The probes used in this study were pmet D, pmet H, XV-2c, KM. 19, and pJ3.11. Linkage to the identified cystic fibrosis locus of 7q22 was established with a peak logarithm of the odds (lod) score of 3.00 at a recombination fraction Θ = 0.00 using the tightly linked marker KM. 19. In addition, we found the D haplotype, which is not commonly associated with cystic fibrosis, to be segregating in this family. The D haplotype is composed of the 1.4-kb allele detectable by XV-2c and the 6.6-kb allele detectable by KM. 19. The three patients with cystic fibrosis who had consanguineous parents were homozygous DD, were among the least severely affected, and had no pancreatic insufficiency. The five patients with unrelated parents were heterozygous for the D haplotype and the commoner B haplotype, except one patient who was homozygous DD. All affected persons with pancreatic insufficiency had the DB genotype. These DNA linkage studies provide additional evidence for the existence of a cystic fibrosis allele that is associated with mild disease.

    Article and Author Information

    • From Duke University Medical Center, Durham, and the University of North Carolina, Chapel Hill, North Carolina. For current author addresses, see end of text.

    • Grant Support: Supported in part by grant UNC CFRDP R001 7-05 from the Cystic Fibrosis Foundation, grants NS26630, HL34322, and RR46 from the National Institute of Health, and funds made available by the Duke Children's Classic and the Bonner Professorship, University of North Carolina School of Medicine.

    • Requests for Reprints: Allyn McConkie-Rosell, MSW, Division of Pediatric Genetics and Metabolism, Box 3028, Duke University Medical Center, Durham, North Carolina 27710.

    • Current Author Addresses: Ms. McConkie-Rosell and Harris, Drs. Chen, Ding, and Kahler: Division of Genetics and Metabolism, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina 27710.

      Ms. Speer and Dr. Pericak-Vance: Division of Neurology, Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710.

      Dr. Highsmith: Division of Molecular Pathology, Department of Pathology, University of North Carolina, School of Medicine, Chapel Hill, North Carolina 27599.

      Dr. Knowles: Department of Medicine, University of North Carolina, School of Medicine, Chapel Hill, North Carolina 27599.

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    1. Ann Intern Med November 15, 1989 vol. 111 no. 10 797-801
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