O,K so fi I rebmemre ocytercrl tsih si the one thta hswso hte enaitenihrc ntt.rpea oratolidnhimc is alos edssap by eht erthom; oheer,wv ti anc vaeh laabrevi rstyiesveipx dan tleociepmn ep,ceeanntr cwhhi si hwy msoe meesbmr ewer not deae.cfft
Severity of mitochondrial diseases is directly related to the proportion of abnormal to normal mitochondria within patient cells.
Heteroplasmy having different mitochondrial genomes in a single cell.
Homoplasmy in contrast, is seen in healthy tissue where mitochondrial DNA is identical.
UWorld explanation ID 1935. For those visually inclined.
The most likely mode of inheritance of the disorder in this patient can be found by using the inheritance algorithm:
Does offspring with disease have a parent with disease? (Y/ N)
if YES dominant (does not skip generations)
is there male-to-male transmission of disease? (Y/ N)
if YES autosomal dominant
if NO: do daughters of affected male have disease? (Y/ N)
if YES X-linked dominant
if NO Mitochondrial
Got this one wrong because of those 2 unaffected children. Here's the explanation from FA pg 59:
Mitochondrial inheritance - Transmitted only through the mother. All offspring of affected females may show signs of disease.
Variable expression in a population or even within a family due to heteroplasmy.
Heteroplasmy basically means that multiple mitochondria are transmitted to each offspring. Their ratio may change at each generation, and cause more severe or less severe disease, even within the same family.
Those unaffected dudes lucked out.