Let’s take a quick look at some of the autosomal dominant disorders that you should be accountable for.
We will cover them in more detail in future lectures. But familial hypercholesterolemia may be not
as prevalent in our society as it is in the Afrikaners society or population. But it certainly is something
that is autosomally dominantly inherited. We also see Huntington’s disease. We’ll cover that
in more detail in a future lecture. Neurofibromatosis, we may not cover in much detail but you do need
to know that’s an autosomal dominant condition. It ends up, there’s fibromatoses or tumors that form
on the nerves and interfere with nerve transmission. There are multiple different outcomes
and expressions of neurofibromatosis. We also see Marfan syndrome. Marfan syndrome is an issue
of connective tissues. These individuals have a pretty difficult time in mobility, maybe even standing up
depending on the degree of expression of this disorder. We might see acute intermittent porphyria.
Now, I bring this one up because it’s very uncommon and frequently misdiagnosed. If you ever have
a patient that’s coming in with intermittent sort of spasming or pains like acute, sharp pains
in the abdomen but through any other technique, you can’t find any phenotypic evidence of it
and it seems like they might be crazy, it could be acute intermittent porphyria which is pretty serious.
So, you want to really treat it. In this day and age, we can do genetic testing to find out whether that’s present.
It can be treated and will have less of an impact on that person’s life. Again, we’ve looked at
polycystic kidney disease, lots of cysts on the kidneys, again an autosomal dominant disorder.
These are certainly disorders that you should keep in mind to make sure that you understand
our autosomal dominant disorders and have a basic understanding of what they are without going into
too much detail. This is a question that I like to consider. Coming from more of an evolutionary perspective,
autosomal dominant alleles, like why do they even persist in the population? You would think
that if something is deleterious and autosomally dominant, then why would they maintain themselves
in the population? Wouldn’t it get selected against in natural selection? The answer to this question
really lays in when the symptoms show up. Earlier, I mentioned that autosomal recessive disorders
show up during childhood. Most autosomal dominant conditions show up in adulthood, most, not all,
show up in adulthood. Because they’re happening after reproductive years, they are maintained
in the population. So before the symptoms show up, people may breed, have offspring, have children
and pass on that anomaly to their offspring. So, the alleles get maintained in the population.
That’s just a little bit of an evolutionary side note. But in short, I’d like to take a quick summary.
We’ve talked about our autosomal recessive disorders as well as autosomal dominant disorders.
I’ve given you some incidences of how they appear in pedigrees as well as some important disorders
that you should keep in mind for your exams. I look forward to moving on with you in the next lecture.