Text of Inheritance Patterns through Pedigrees MMHS Science Mr. Chitraroff
Inheritance Patterns through PedigreesMMHS ScienceMr. Chitraroff
Main Inheritance TypesAutosomal RecessiveAutosomal DominantX-Linked (Sex-Linked) RecessiveX-Linked (Sex-Linked) DominantAutosomal = Inherited on the body chromosomes #1-44.Sex-Linked = Inherited on the Sex Chromosomes #45 & 46. (XX or Xy)
Autosomal Dominant TraitsAlmost all individuals will be heterozygous. (Hh)
Every affected individual has an affected biological parent. There is no skipping of generations. 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. Normal siblings of affected individuals do not transmit the trait to their offspring.
There are never carriers (half-shaded symbols).
Autosomal Dominant Disorders
Huntingtons DiseaseSymptoms 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 (43)PolydactlyDisorder of more than 5 fingers or toes per appendage.
a legal dwarf
Autosomal RecessiveTraits will often skip a generation.Parents may not have the trait, but can pass it on to offspring. (e.g. Het)Males and Females are equally affected.Both parents can be carriers. (half-shade)
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 InheritanceWhich Type of Inheritance is this?
AlbinismrevealedCircled symbols show Heterozygous Individual (Aa)Whats gross about this pedigree?
Jamaican Albino Yellow Mon
Sex-Linked TraitsPassed on from the (X) Sex Chromosome.Fathers pass trait on to daughters.Mothers pass trait on to daughters or sons.Usually skips a generation.Males more likely affected than females.Female carriers possible, not males.
Sex Linked RecessiveExamples:Color-blindnessDuchenne 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.