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Molecular Testing: Applications in Screening Newborns for Hemoglobinopathies and Galactosemia

Molecular Testing: Applications in Screening Newborns for Hemoglobinopathies and Galactosemia. Michael Glass Washington State Department of Health. In the Beginning: Science, November1949. May1972. National Sickle Cell Anemia Control Act Funds and promotes population screening and education.

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Molecular Testing: Applications in Screening Newborns for Hemoglobinopathies and Galactosemia

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  1. Molecular Testing:Applications in Screening Newborns for Hemoglobinopathies and Galactosemia Michael Glass Washington State Department of Health

  2. In the Beginning:Science, November1949

  3. May1972 National Sickle Cell Anemia Control Act Funds and promotes population screening and education

  4. Solubility Test

  5. Alkaline Electrophoresis(cellulose acetate) AFSC Control AE FAC FAS

  6. 1986 Prophylaxis with Oral Penicillin in Children with Sickle Cell Anemia • Marilyn H. Gaston, M.D., Joel I. Verter, Ph.D., Gerald Woods, M.D., Charles Pegelow, M.D., John Kelleher, M.D., Gerald Presbury, M.D., Harold Zarkowsky, M.D., Elliott Vichinsky, M.D., Rathi Iyer, M.D., Jeffrey S. Lobel, M.D., Steven Diamond, M.D., C. Tate Holbrook, M.D., Frances M. Gill, M.D., Kim Ritchey, M.D., John M. Falletta, M.D., and For the Prophylactic Penicillin Study Group N Engl J Med 1986; 314:1593-1599 June 19, 1986

  7. 1987 NIH Consensus Conference: “The benefits of screening are so compelling that universal screening should be provided…”

  8. The α,β,λ’s of The Hb Molecule

  9. Isoelectric focusing FA ASFC control FA AA FA

  10. Hemoglobin ~7500 Asian infants born in WA each year

  11. Science 1985

  12. Human Genetics 1987

  13. Science1988 • Science 29 January 1988: Vol. 239 no. 4839 pp. 487-491 DOI: 10.1126/science.2448875 • Primer-directed enzymatic amplification of DNA with a thermostable DNA polymerase • RK Saiki, et. al • Cetus Corporation, Department of Human Genetics, Emeryville, CA 94608.

  14. 1994 Washington adds DNA/PCR to the routine screening algorithm for hemoglobinopathies.

  15. DNA/PCR Methods

  16. Normal wild type mutant type

  17. Heterozygote wild type mutant type

  18. Homozygote mutant type wild type

  19. Hemoglobin Screening Protocol: IEF → HPLC → DNA/PCR Mutations: -globin: S, E, C, (-globin: Constant Spring)

  20. Hemoglobin

  21. Limitation/Caution DNA is helpful but not perfect: No response from the HbA probe can be due to a thalassemia deletion that encompasses the site.

  22. Galactosemia Washington was the last to add (2004) Lessons learned from others: • Deadly disorder • Galt enzyme labile in heat and humidity • Duarte variant modifies severity

  23. Galactosemia Screening Protocol: GALT enzyme → Total galactose → DNA/PCR Mutations: Q188R, S135L, K285N, & N314D (Duarte variant)

  24. Galactosemia frequency of classic alleles of 250 patients in the U.S. (from genetests.org)

  25. Galactosemia *DNA analysis should already have been done on first specimen

  26. Galactosemia DNA results on 41 infants

  27. Galactosemia for G/? genotype

  28. Limitations/Caution DNA is helpful but not perfect: A D/G finding does not always mean a DG phenotype: • They could be on the same chromosome • There may be another severe mutation that is not on the screening panel.

  29. Other Approaches • DNA Bead Technology • LightCycler • Microarrays • Sequencing • etc

  30. Summary Second tier targeted DNA has provided additional valuable information in WA to guide follow-up for hemoglobins, galactosemia

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