Notes Pedigrees Orderly diagram of a familys genetic

Notes: Pedigrees Orderly diagram of a family’s genetic traits

A pedigree shows… • relationships, sex, genotype & phenotype of each member • if an allele is dominant or recessive • if an allele is autosomal or sex-linked

Symbols • Circle = female • Square = male • Horizontal line = parents • Vertical line = children • Symbol w/line through it = dead

More symbols • Half-Shaded = heterozygous not affected (recessive disorder) • Completely darkened = homozygous affected • Half-Darkened = heterozygous affected (dominant disorder)

Pattern #1 - Autosomal Dominant • In general, males & females equally affected • NO skipping generations • Trait is expressed if allele is present

AD EX: Huntington’s disease • Build up of protein causes damage to nerve cells in brain • Most people develop symptoms in 40 s-50 s • Symptoms start w/movement problems, slurred speech, balance problems, swallowing difficulties Huntington disease (right) showing a larger cavity where brain cells have died,

Pattern #2 – Autosomal Recessive • In general, males & females equally affected • Can skip generations • Both parents are carriers • Trait is expressed only if homozygous

AR EX: Cystic Fibrosis • Defective chloride-ion transport protein in cell membranes • Symptoms – thick, heavy mucus clogs lungs, liver, pancreas • Most people do not survive past late 30 s • Many treatments for symptoms, but NO cure

Pattern #3 - Autosomal • In general, males & females equally affected • Father-child transmission of trait

Pattern #4 – Sex-linked recessive • In general, more males are affected than females • If mom is carrier sons are affected, not daughters • If dad is affected daughters are carriers • NO dad-son transmission • NO male carriers

EX: Red-Green Color Blindness • Affects males more than females • 3 types of cone cells working together give you color vision (red, blue, green)

EX: Hemophilia • • Affects males more than females Missing blood clotting proteins Lots of bleeding from minor cuts Can suffer internal bleeding from bumps/bruises • Can be treated w/injections of clotting proteins

Try this one • Autosomal dominant

Autosomal recessive

Dominant - Autosomal

Recessive - Autosomal

Recessive, X-linked

Recessive - Autosomal

Dominant - Autosomal

Recessive, X-linked

Autosomal recessive

X-linked recessive