Thread by @Biotech2k1

#Inheritance_Patterns

Pedigrees and Linked genes.

1/ The pedigree is a diagram that is used to track a trait across a family tree. It might be cool to track the trait of red hair in your family. The pedigree is critical for tracking a genetic disease through a family to determine what the risk of inheritance.

2/ There are some basics to drawing a pedigree. The lines connect lineages with the males being the squares and the females being the circles. Some pedigrees will use a slash / to cross out deceased people in the pedigree. There are some basics to drawing a pedigree.

3/ Anyone who had the trait, but not the disease gets a small colored circle in the center. Those that have the actual disease get fully colored in. The lines show the children from each generation and their mates.

4/ The roman numerals on the left mark each generation.

5/ By looking at the patterns of inheritance, we can quickly see how the trait is passed. If the trait affects both males and females, its an autosomal trait. If it only affects males or females, then its a sex chromosome linked disease.

6/ If the disease affects every generation, it is a dominant trait. An autosomal dominant trait will affect about 50% of both males and females from an affected parent who is heterozygous.

7/ Recessive traits tend to skip generations and can often skip several generations as many parents get the trait, but not the full disease. From the chart above, we can quickly see this represents a trait that is autosomal dominant.

8/ #Haplotype

Haplotype is a group of genes that are all inherited together from a single parent. This brings up the concept of linked genes. Transmission genetics will often treat genes as they are on different chromosomes.

9/ There are many genes on each chromosome. You only get 1 chromosome from each parent. That means you will inherit large groups of genes together. Large parts of the chromosomes never experience crossing over so they are linked together.

10/ One of the best examples of linked genes is the haplotype of Human Leukocyte Antigen genes. There are hundreds of these genes on Chromosome 6 that make up our self antigens. When you inherit them, you get all of them from a single parent.