A hand book of life sciences/CLASSICAL GENETICS
PEDIGREE ANALYSIS
[edit | edit source]=== PATTERNS OF INHERITANCE ===[1]
AUTOSOMAL DOMINANT
[edit | edit source]- Each affected person has an affected parents.
- It occurs in every generation.
- There is male to male transmission.
Ex: Huntington's chorea,Neurofibromatosis,Achondroplasia,Familial hypercholesterolemia
AUTOSOMAL RECESSIVE
[edit | edit source]- Most affected individuals have unaffected parents.
- Both parents of unaffected persons are carriers but offsprings are affected.
- Trait often skips generations.
Ex:Sickle cell anemia,Cystic fibrosis,Phenylketonuria,Tay-Sachs disease
X-LINKED DOMINANT
[edit | edit source]- Females are more frequently affected from mothers.
- Affected females comes from affected mothers or fathers.
- If the male is affected then all of his daughters would be affects but non of his sons are affected.
- If the female is affected then about half of her sons are affected.
- It present in each generation.
Ex:Hypophatemic rickets (vitamin-D resistant rickets), Ornithine Transcarbamylase deficiency
X-LINKED RECESSIVE
[edit | edit source]- Most affected individuals are male.
- Affected males comes from mother who are affected or carriers.
- Affected females comes affected father and affected or carrier mother.
- Affected males present in each generation.
Ex:Hemophilia A,Duchenne Muscular Dystrophy,Colour blindness, Night blindness,Fragile X-syndrome
Y-LINKED INHERITANCE
[edit | edit source]- It is also known as holandric inheritance.
- Affects only Males.
- Affected males always have an affected father.
- If the fathers will affected,all of his sons will be affected.
Ex:Flatfoot and hair loss
MITOCHONDRIAL DISORDERS
[edit | edit source]- This inheritance can affect both males and females.But only passed on by females.
- It can appear in every generation.
Ex:Mitochondrial myopathy, Diabetes mellitus and deafness(DAD)