NATS 1675 Lecture 30: L30 Pt 2 Principles of Inheritance
4 Aug 2015
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If a person carries two dominant or two recessive alleles for the same trait, they are said to be homozygous. If the two alleles are different, the person is said to be heterozygous. Chromosomes number 1-22 are termed autosomal to differentiate them from sex chromosomes. Traits which are controlled by genes carried on these chromosomes are also termed autosomal. Three forms of autosomal inheritance are recognized: autosomal dominant, autosomal recessive, incomplete dominance/co-dominance. Autosomal recessive alleles are usually mutations which do not code for an enzyme or other type of protein needed for normal body function. Thus they are often referred to a non-working . Most common fatal genetic disorder in north america. Delayed lethal genotype: death usually occurs by age 2-5 years. Due to mutation in gene for hexaminase enzyme needed to remove waste products from nerve cells. Genetic testing available for carrier state (heterozygotes) Can be diagnosed in newborn by eye test. Currently there is no cure for condition.
