-Leads to Dz's if only one allele is Altered (A)
-Usually do to mutations in structural genes
-In one parent affected, every child has 50% risk of inheriting the altered allele, thus Dz's.

(Autosomal Dominant Polycistics kidney disese, achondroplasia, Huntingtons, Marfan, Ehlerers-Danlos Syndrom.

-Dz's occurs only if both alleles are altered.
-Mostly enzyme deficiencies.
-Onset of disease often in childhood and symptoms are usually more severe than autosomal dominant.

-Heterozygotes of recessive disease are known as carriers and show no phenotype of Dz's.

-If both parents heterozygotes carries, the offspring has a 25% probability of getting disease, 50% of becoming carrier and 25% of being unnaffected.

-Allele responsible for Dz's on X-chromosome.
-Women are carriers and only affected if both X-chromosomes carry affected allele.

-Children have a 50% of inheriting the altered x-chromosome. Sons develop disease and daughters are carriers.
-skips generations

-Men whose only X-chromosome carries altered allele, will always develop the disease.

-All daughters inherit the altered X-chromosome: Carriers.
-All sons that inherit the healthy X from mom: healthy!

Ex. color blindness, hemophilia A/B. G6PD deficiency, Duchene muscular dystrophy, Lesch-Nyhan syndrome,, becker muscular dystrophy

In X-linked recessive inheritance, all male offspring of the affected father (and a healthy mother) are healthy, do not carry the altered allele, and therefore cannot pass on the altered allele!

The allele responsible for disease is on the X-chromosome.
Both men and women affected. Affected fathers pass altered allele to daughters and not to sons.
Ex. Rett Syndrome, Alport Syndrome, rickets

Maternally inherited, any offspring of an affected mother shows signs of disease. mitochondrial myopathies (e.g., MELAS syndrome), Leber hereditary optic neuropathy.

DO NOT Follow Mendelian Laws of Inheritence Ex. type 1 and type 2 diabetes mellitus, hypertension, androgenic alopecia, atopy, schizophrenia, and Alzheimer disease