BASIM ZWAIN LECTURESMEDICAL PHYSIOLOGY

PATTERNS OF INHERITANCE

Professor Dr. Basim Zwain

Faculty of Medicine

Jabir ibn Hayyan Medical University

basimzwain@jmu.edu.iq

PATTERNS OF INHERITANCE

Inheritance pattern Description ExamplesAutosomal dominant One mutated copy of the gene in each cell

is sufficient for a person to be affected by an autosomal dominant disorder. Each affected person usually has one affected parent . Autosomal dominant disorders tend to occur in every generation of an affected family.

Huntington disease,neurofibromatosis type 1

Autosomal recessive Two mutated copies of the gene are present in each cell when a person has an autosomal recessive disorder. An affected person usually has unaffected parents who each carry a single copy of the mutated gene (and are referred to as carriers) . Autosomal recessive disorders are typically not seen in every generation of an affected family.

cystic fibrosis, sickle cell anemia

PATTERNS OF INHERITANCEInheritance pattern Description ExamplesX-linked dominant X-linked dominant disorders are caused by

mutations in genes on the X chromosome. Females are more frequently affected than males, and the chance of passing on an X-linked dominant disorder differs between men and women . Families with an X-linked dominant disorder often have both affected males and affected females in each generation. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons (no male-to-male transmission).

fragile X syndrome

X-linked recessive X-linked recessive disorders are also caused by mutations in genes on the X chromosome. Males are more frequently affected than females, and the chance of passing on the disorder differs between men and women . Families with an X-linked recessive disorder often have affected males, but rarely affected females, in each generation. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons (no male-to-male transmission).

Hemophilia,Fabry disease

PATTERNS OF INHERITANCEInheritance

pattern Description ExamplesCodominant In codominant inheritance, two different versions

(alleles) of a gene can be expressed, and each version makes a slightly different protein . Both alleles influence the genetic trait or determine the characteristics of the genetic condition.

ABO blood group,alpha-1 antitrypsin deficiency

Mitochondrial This type of inheritance, also known as maternal inheritance, applies to genes in mitochondrial DNA. Mitochondria, which are structures in each cell that convert molecules into energy, each contain a small amount of DNA. Because only egg cells contribute mitochondria to the developing embryo, only females can pass on mitochondrial mutations to their children . Disorders resulting from mutations in mitochondrial DNA can appear in every generation of a family and can affect both males and females, but fathers do not pass these disorders to their children.

Leber hereditary optic neuropathy (LHON)