I got this Q wrong. I was wondering why this patient โhas no personal or family historyโ. Hereditary spherocytosis should be a AD disease, so, generally speaking, this diz should be seen in each generation, right?
Can anyone answer why this one can't be F. Beta thalasemia major? I was thinking becaues of his anemia and the "european descent" which includes the mediteranian europeans. Unless NMBE writers think that european only means the ones with extra white people lol
I think the key to this question is to use elimination for facts that we know for sure. The first is that it's a normocytic anemia, so all thalassemias are rule out since thal = microcytic.
That leaves A and D. Since the MCHC is normal (which is not what we would expect for hereditary spherocytosis) and the patient's symptoms are severe, they must have a "milder" version of the disease (e.g. achondroplasia is also autosomal dominant and is lethal if you get the homozygous form).
Obviously some big leaps in reasoning here but that's one path to the right answer
HS is autosomal dominant, but exhibits incomplete penetrance. So he had no record of personal family, but still likely heterzygous.
(Wikipedia) The clinical severity of HS varies from symptom-free carrier to severe hemolysis because the disorder exhibits incomplete penetrance in its expression.
Auto dom disease are usually heterozygous (or so they want us to assume)
Can anyone justify why they did not describe an increased MCHC? FA 2019 says spherocytosis has high MCHC, and they did not even have it on the upper end of normal.
submitted by โnala_ula(127)
The histology is of spherocytes (small spherical cells w/o central pallor). Hereditary spherocytosis is due to defect in proteins interacting with RBC membrane skeleton and plasma membrane (ankyrin, band 3, protein 4.2, spectrin). Mostly autosomal dominant inheritance (so heterozygous mutation since you only need one mutant allele to get the disease).