Mitochondrial Inheritance,MULTIFACTOR

How are mitochondrial diseases inherited?

Maternally: Only mothers transmit mtDNA to all offspring.
Paternally-inherited mtDNA is not transmitted.
Affects both sons and daughters, but only daughters pass it on.

Why are mitochondrial diseases often multisystemic?

Because mitochondria are responsible for energy production, so high-energy-demand tissues (brain, heart, muscles, kidneys) are commonly affected.

What is heteroplasmy in mitochondrial inheritance?

A state in which cells contain both normal and mutated mtDNA. The ratio determines disease severity and expression.

List examples of mitochondrial diseases.

MELAS (Mitochondrial Encephalopathy, Lactic Acidosis, Stroke-like episodes)
Leber’s hereditary optic neuropathy
Leigh syndrome
MERRF (Myoclonic Epilepsy with Ragged Red Fibers)
Kearns-Sayre syndrome

What is multifactorial inheritance?

It involves
multiple genes
(polygenic) and
environmental factors
working together to cause a condition.

What is heritability in multifactorial diseases?

It’s a measure of how much of the variation in a trait is due to genetic differences.

What is genetic predisposition?

It’s an increased likelihood of developing a disease due to inherited genetic factors. Disease only manifests if certain environmental thresholds are crossed.

How does multifactorial inheritance differ from Mendelian?

No clear dominant/recessive pattern
Risk increases with number of affected relatives
Traits show continuous variation (e.g., height, blood pressure)

Examples of multifactorial diseases?

Diabetes mellitus
Hypertension
Heart disease
Schizophrenia
Breast/ovarian cancer
Neural tube defects