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What are the 4 classifications of genetic disorders?
- errors of morphogenesis
- chromosomal abnormalities
- single-gene defects
- polygeneic inherited disease
What are errors of morphogenesis?
- Zygotes have all genes found as an adult.
- Zygote expresses or activate genes in a specific manner during different stages of development.
- Genes can be abnormally activate or abnormal genese can be activated.
- --> restults in agenesis (organ missing), hypoplasia (incomplete dev), involution failure (fetal structrues fail to involute)
- Structural chromosomal abnormalities are:
- 1. translocations
- 2. deletions
- 3. inversions
- 4. Formation of ring chromosomes
chromosomal abnormalities are:
- 1. Monosomy: absence of 1 eg Turner Syndrome
- 2. Trisomy: extra copy eg - Down Syndrome
Single - Gene Abnormalities:
- 1. Autosomal dominant: Marfran Syndrome.
- 2. Autosomal recessive- phenylketonuria
- 3. X-linked inheritance- hemophilia
- - disease process reflecting abnormal genes + environ factors eg HTN
- - disorders run in families bc they share genes and environment
What is Down Syndrome?
- congenital (numerical chromosomal abnormality of trisomy) syndrome
- mental retardation
- large tongue, mongol appearance
- heart disease, intestinal stenosis, leukemia
- 21st trisomy
- high risk w/ advanced maternal age
What is Marfan Syndrome?
- ex of single-gene abnormality (autosomal dominant)
- connective tissue disorder
- involves ocular, skeletal, cardiovascular systems
- Tall stature, disproportionately long extremities, ectopia, myopia, aortic root dilation, aneurysms
What is Hemophilia?
- Serious inherited (x-linked recessive single gene abnormality)
- disorder of blood clotting that results in spontaneous bleeding, particularly into joints, muscles & internal organs
- Hem A:
- mutation in gene for factor VIII
- Hem B:
- mutations in gene for factor IX