inheritance and pedigree analysis

Many diseases such as cancer, huntington's disease, diabetes, cystic fibrosis and tay sachs are all hereditary. Though each one can be inherited differently. Pedigree charts are often used to show the inheritance of something between family members and can also be used to figure out which time of inheritance it is. The different types of inheritance I will be discussing are x-linked dominant, x-linked recessive, y-linked, autosomal dominant and autosomal recessive.

x-linked dominant - x-linked dominant disorders are disorders located on the x chromosome. There are few disorders that inherit x-linked dominant inheritance. Examples include: Rett syndrome, Aicardi syndome, and Klinefelter symdrome. With x - linked dominant, the disorder is never passed from father to son. All daughters of an affected father and a normal mother will be affected, while all sons will be normal. 1/2 of the sons and 1/2 of the daughters of an affected mother and normal father will be affected as well. Females are more likely to be affected then males and most x-linked disorders are lethal in males.

x-linked recessive- x-linked recessive disorders are also located on the x chromosome, and are more common then x-linked dominant. Examples of x-linked recessive disorders are: Hemophilia A, Duchenne Muscular Dystrophy, Lesch - Nyhan syndrome, male pattern baldness, color blindness and Turner syndrome. The x-linked recessive is also never passed from father to son. Males are much more likely to be affected then females are. All affected males are affected because of their mother. It is usually passed from the affected to grandfather to his carrier daughters, which affect half of the grandsons.

y - linked - Y-linked disorders are located on the y chromosome and are very few. The most common one is male infertility. Since only males inherit a y chromosome, all of the sons of an affect male will also be affected while none of the daughters will be.

autosomal dominant - autosomal disorders mean that only one mutated copy of a gene is required for a person to be affected by an autosomal dominant disorder. Each affected person had a least one affected parent, and there's a 50% chance of a children of an affected parent will get the disorder. Some examples of autosmal dominant Huntington's disease, Marfan syndrome and Familial hypercholesterolemia. Autosomal dominant disorders do not skip generations. Males and females both have equal likelihood of inheriting the disorder.

Autosomal recessive - Autosomal recessive disorders are like autosomal dominant disorders, but two copies need to be inherited instead of one. Some examples of autosomal recessive disorders are: cystic fibrosis, sickle-cell disease, tay-sachs disease and roberts syndrome. In autosomal recessive disorders males and femals are equally likely to inherit the disorder. Disorders often skip generations, and affected children can be born to unaffected parents.