Question

describe common genetic and congenital alterations.

Answer 1

# Genetic disorders are :-

-mutation in the gene

-may or may not be present at birth

-genetic disorders may be:

-single-gene disorders

-multifactorial (multi-gene disorders)

# Single gene disorders are :-

-caused by a single defective or mutant gene

-effects may be seen in different parts of the body

-over 8000 known single gene disorders

# Autosomal dominant

-single mutant gene that is transmitted to offspring regardless of sex. Each offspring regardless of sex, has a 50%chance of developing the disorder

-Huntington disease

-Marfan syndrome

-Neurofirbomatosis

# Autosomal recessive

-only occur when both members of the gene pair are affected

-may affect both sexes

-both parents may be unaffected but may be carriers of the defected gene

-onset is usually early

-most disorders are caused by an enzyme deficiency rather than a structure problem

# Phenylketonuria

-autosomal recessive

--rare metabolic disorder caused by a deficiency in the liver enzyme needed to change phenylalinine to tyrosine

--phenylalinine build up can lead to mental retardation

-treat with special diet

# X-linked disorders

-sex linked disorders

-almost always on the X chromosome

-almost always recessive

Ex: hemophilia A, G6PD deficiency

# Multifactorial inheritance disorders

-caused by problems in multiple genes

-usually an environmental agent is involved

-usually dont follow a clear pattern

-may or may not be evident at birth

# Chromosomal disorders may be due to:

-an alteration in the structure of the chromosome

-alteration in the duplication of the chromosome

-alteration in the number of chromosomes

- Examples are Downs Syndrome , Edwards syndrome etc