Inheritance Patterns through Pedigrees MMHS Science Mr. Chitraroff

Main Inheritance Types 1.Autosomal Recessive 2.Autosomal Dominant 3.X-Linked (Sex-Linked) Recessive 4.X-Linked (Sex-Linked) Dominant Autosomal = Inherited on the body chromosomes #1-44. Sex-Linked = Inherited on the Sex Chromosomes #45 & 46. (XX or Xy)

Pedigree Symbols

Autosomal Dominant Traits 1.Almost all individuals will be heterozygous. (Hh) 2.Every affected individual has an affected biological parent. There is no skipping of generations. 3.Males and females have an equally likely chance of inheriting the mutant allele and being affected. The recurrence risk of each child of an affected parent is 1/2. 4.Normal siblings of affected individuals do not transmit the trait to their offspring. 5.There are never carriers (half-shaded symbols).

Autosomal Dominant

Autosomal Dominant Disorders DiseaseSymptoms Huntington’s Disease Symptoms may include involuntary movements and loss of motor control. In addition, personality changes may occur, with loss of memory and decreased mental capacity. Achondroplasia (dwarfism) Achondroplastic dwarfs have short stature, with an average adult height of 131 cm (4’3”) Polydactly Disorder of more than 5 fingers or toes per appendage.

Jason Acuna aka “Weeman” a legal dwarf

Polydactly

Autosomal Dominant

Autosomal Recessive 1.Traits will often skip a generation. 2.Parents may not have the trait, but can pass it on to offspring. (e.g. Het) 3.Males and Females are equally affected. 4.Both parents can be carriers. (half-shade)

Autosomal Recessive Examples: Examples: *Cystic fibrosis *Tay-Sach’s disease Males and females are equally likely to be affected. The recurrence risk to the unborn sibling of an affected individual is 1/4. The trait is characteristically found in siblings, not parents of affected or the offspring of affected. Parents of affected children may be related. The rarer the trait in the general population, the more likely a consanguineous mating is involved.

Albinism Inheritance Which Type of Inheritance is this?

Albinism…revealed Circled symbols show Heterozygous Individual (Aa) What’s gross about this pedigree?

Jamaican Albino “Yellow Mon”

Sex-Linked Traits 1.Passed on from the (X) Sex Chromosome. 2.Fathers pass trait on to daughters. 3.Mother’s pass trait on to daughters or sons. 4.Usually skips a generation. 5.Males more likely affected than females. 6.Female carriers possible, not males.

Sex Linked Recessive Examples: –Color-blindness –Duchenne Muscular Dystrophy The disease is never passed from father to son. Males are much more likely to be affected than females. All affected males in a family are related through their mothers. Trait or disease is typically passed from an affected grandfather, through his carrier daughters, to half of his grandsons.

Sex-Linked Recessive Disorders Hemophilia-blood doesn’t clot Colorblindness—Can’t see certain colors. Duchenne Muscular Dystrophy—degenerative breakdown of muscles. Duchenne Muscular Dystrophy—degenerative breakdown of muscles. Anosmia – Inability to smell.