Descriptive Epidemiology in Genetic Epidemiology

Abstract

Genetics has come to play an increasingly important role in studies of health and disease driven both by new technologies that enable these studies (chromosome analysis, DNA sequencing, genotyping) and by our recognition of the key role of genes and genetic variation in disease causation. Humans have 23 pairs of chromosomes made up of some 3 billion nucleotides (A, C, G, and T) of DNA. There are over 20,000 genes scattered across the human chromosomes, most containing in their DNA sequences the information for the amino acid sequence and time/place of expression of a particular protein. We receive one chromosome (and one copy of each of the genes on that chromosome) from our mother and one from our father. Variation in the DNA sequence can result in different alleles or forms of the gene and these individual differences are inherited according to Mendel’s laws of transmission resulting in dominant, recessive, or X-linked forms of inheritance.