genetic factors and disease Flashcards
3 causes of disease
genetic (down syndrome)
multifactorial (spina bifida)
environmental (poor diet)
genotype
genetic constitution of an individual
phenotype
appearance of an individual (physical, biochemical, physiological) which results from the interaction of the environment and the genotype
Allele
one of several alternative forms of gene at a specific locus, normal allele; wild type, disease allele carrying a pathogenic variant
Polymorphism
frequent hereditary variations at a locus
Homozygous
both alleles the same at a locus
Heterozygous
alleles at a locus are different
Hemizygous
only one allele refers to a locus on a X chromosome in a male
Autosomal dominant inheritance
disease which is manifest in the heterozygous state (Huntington’s disease)
Autosomal recessive inheritance
disease which is manifest in the homozygous state (e.g. cystic fibrosis)
X-linked inheritance
caused by pathogenic variants in genes on the X chromosome (haemophilia)
mitochondrial disorders
mutations can cause severe childhood onset conditions such as epilepsy
imprinting
for some genes only 1 out of the 2 alleles is active, the other is inactive. For particular genes it is always the paternal or the maternal allele
multifactorial conditions
diseases that are due to a combination of genetic and environmental factors most common diseases are multifactorial
Rare Genetic subset of a multifactorial disease – Familial Hypercholesterolaemia and Coronary Heart Disease
- Lipids absorbed in intestinal cell packaged with proteins. In the liver associated with cholesterol to form lipoproteins
- High levels of low density lipoproteins associated with increased risk of heart disease
- Some people have a pathogenic variant in the gene for LDL receptor and have increased genetic predisposition for CHD
