640Lecture0705

640Lecture0705 - TYPES OF GENETIC VARIATION protein...

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1 TYPES OF GENETIC VARIATION Morphological variation Protein variation Nucleic acid variation ultimately DNA protein variation • how do we measure variability – structural similarity? how • immunology • Variation in enzyme activity • indirect structural differences (electrophoresis) • amino acid similarity (sequence) enzyme activity • glucose-6-phosphate dehydrogenase – X-linked locus –protein variants with known clinical effects G-6-PD • Large number of variants with activity differences – Significance of many unclear – Some polymorphic alleles associated with enzyme deficiency and red cell hemolysis (hemolytic anemia) – G6PD deficiency sensitivity following treatment with antimalarial drugs (primaquine) and "favism" G-6-PD Frequency of G6PD deficiency associated with primaquine sensitivity about 10% of blacks <1% Caucasian (usually Mediterranean) + association with localities with increased malaria G-6-PD • examine enzyme variability of definable genetic variants in populations does it correlate with other biochemical phenotype ? (specifically, electrophoretic phenotypes) –Enzyme activity only partially correlated with electrophoretic mobility
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1 Distribution of G6PD activity
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2 frequency of G6PD deficiency in various Male Jewish Population samples E.R. GIBLETT, GENETIC MARKERS IN HUMAN BLOOD, 1969 STARCH GEL ELECTROPHORETIC PHENOTYPES FOR G6PD VARIANTS A B
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1 Over 115 alleles identified most are rare variants almost all cause decreased activity 6 alleles frequent in some populations What variants are known and how many are polymorphic Many G6PD variants now known some polymorphic in specific populations Med & Near East 100 0-7% Mediterranean S.E.Asia 105 4-24% Canton Blacks 110 8-20% A- Greece 98
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640Lecture0705 - TYPES OF GENETIC VARIATION protein...

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