文档介绍：单基因遗传病高级遗传
Etiology of diseases. For any condition the overall balance of genetic and environmental determinants can be represented by a point somewhere within the triangle.
Classification of Genetic Disorders
Single gene disorders are caused by defects in one particular gene, and often have simple and predictable inheritance patterns. They affect about 1 per cent of the population as a whole.
Epigenetic modifications？
Other reasons?
Multifactorial (common)
Variants in genes causing alteration of function
“Environmental” influences act on a genetic predisposition to produce a liability to a disease.
One or more organ system affected.
Person affected if liability above a threshold.
Single gene (1% liveborn)
Mutations in single genes (often causing loss of function)
Dominant/recessive pedigree patterns (Mendelian inheritance).
Can affect structural proteins, enzymes, receptors, transcription factors.
Chromosomal (% liveborn)
Thousands of genes may be involved.
Multiple organ systems affected at multiple stages in gestation.
Usually de novo (trisomies, deletions, duplications) but can be inherited (translocations).
Classification of genetic disorders
+ environment
Male
Mitochondrial
Somatic mutations (cancer)
Single gene disorders:
disorders in which inheritance is due to a single mutant gene
Mendelian inheritance
Genes are units of heredity, based in DNA
Phenotype (physical or functional abnormalities)
Genotype (DNA change)
4. Autosomal vs X-linked
determined by whether the responsible gene is
carried on one of the autosomal chromosomes
or on the X chromosome
5. Dominant vs Recessive , based on phenotypic
expression
Recessive
Homozygotes with two copies of the altered gene are affected
Dominant
Heterozygotes with one copy of the altered gene are affected
X-linked recessive
Males with one copy of the altered gene on the X-chromosome are affec