Question

what will the feature of mitochondrial dna will contribute to intra-family phenotypic variability in mitochondria disorders...

lack of recombination

threshold effect of heteroplasmy.

strict maternal inheritance

low mutation rate relative to nuclear dna

imprinting

Answer 1

Strict maternal inheritance..

Mitochondrial DNA (mtDNA) in humans are always inherited from person's mother and in this way we share the our mitochondrial DNA sequence with our mothers ,sisters,grandmothers and brothers. So it is inheritance pattern which share common mt DNA with our siblings.Mitochondrial DNA posses high variability due high rate of mutation , it shows significant variabilty in unrealted person.

Phenotypic variability in mitochondrial disorder is mainly due to mutation in mitochondrial gene that have passed from mother. when these mutated mitochondrial gene passes from mother to children ,there is a occurence of phenotypic disoredr in intra-famy