BIOL239 Lecture Notes - Sickle-Cell Disease, Intellectual Disability, Pleiotropy
20 May 2013
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Document Summary
Pedigree analysis: many human traits run in families : most do not show a simple mendelian pattern of inheritance. Abnormal hemoglobin, sickle-shaped red cells, anemia, blocked circulation, increased resistance to malaria. Single nucleotide substitution results in incorrect amino acid, resulting in a change in conformation of them -globin protein when deoxygenated. Sickle cell anemia is a syndrome: the phenotype varies. Missing enzyme; build-up of fatty deposit in brain;nbuild-up destroys nervous development; blindness, paralysis, mental retardation. Mutation in enzyme in metabolic pathway causes the amino acid phenylalanine to build up. Body deals with this by converting it to phenylpyruvic acid which interferes with early development of the nervous system; mental deficiency in untreated young: examples of single-gene traits in humans. Missing enzyme in pathway to melanin production; unpigmented skin, hair and eyes. Progressive mental and neurological damage; neurologic disorders by ages 40-70. Mutation caused by extra nucleotide repeats cag in the gene. Adds extra glutamine amino acids to the protein.
