Hereditary Diseases

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Mendelian Condition-

Originate as one or more mutation in a single gene, usually of a large effect. These can be simple Mendelian or may have some exception (X-linkage or incomplete dominance. Example would be Huntington’s disease

Complex Diseases/ Polygenic or Multifactorial Diseases-

Occur throughout the influence of multiple genes along with non-genetic (ex. diabetes, heart disease, and certain types of cancer.

• Prevalence and patterns in inheritance vary

• Much more difficult to study and predict- prediction are probabilistic

Diabetes

• Environmental and genetic components are important

• Actually multiple diseases all characterized by high blood glucose level but having different genetic causes

• Type 1- autoimmune, Type 2- non-autoimmune

Chromosomal Conditions

• Presence of an extra chromosome, the absence of a chromosome, the duplication or deletion of a chromosome segment, and certain structural rearrangements of chromosomes can each lead to developmental and physical abnormalities (Ex. down syndrome, cri-du-chat syndrome, and Prader-Willi Syndrome

• Some hereditary and some are spontaneous and not passed down in families. Less tolerated for autosomes and can be not a disease (bc gene dosing changes and this can have a major impac t espcecially if the genes changes while being expressed

Down Syndrome

• May not be inherited

• Caused by three copies of the 21st chromosome

• Heritable in about 3% of the cases- caused by translocation