Pedigree Analysis

The pedigree analysis helps one to foresee possible genetic defects in the progeny and if possible to avoid them.Genetic counselling in order to create better human being in the future become possible through pedigree analysis.

Pedigree analysis is one of the best methods of analysing inheritance study.It determines the mode of inheritance of a trait whether dominant or recessive,autosomal or sex linked.It also helps in the study of linkage analysis.Pedigree is a chart or diagram representing the ancestral history of an individual.This is a schematic means of showing genetic relationship among individuals.

The pedigree pattern provides information on the Mendelian principles of segregation,independent assortment,allelism,linkage and more effectively on single factor inheritance.

Study of a particular trait in a family usually begins with an affected person who is referred to as the proband or propositus and is marked by an arrow.Generations are numbered with Roman Numerals and range from the earliest at the top pf the pedigree chart to the most recent at the bottom.If the trait is inherited it will be reflected in the pedigree generations.In case of autosomal mode of inheritance the trait will be observed in both male and female.In X linked inheritance generally the females are carriers and they transmit the abnormality  to 50% of their male children.The abnormality is manifested in the males and the trait is never transmitted directly from father to son,But in Y linked  inheritance genes and  Y chromosomes are passed down exclusively  along male  lines.In autosomal  dominant inheritance every affected person normally must have an affected parent and affected children in 1:1 ratio/