00:01Coming to this topic, predominance of autism in males more than in females, first we need
00:09to remember that the ratio of incidence is four times higher in males compared to females.
00:18It is 4 is to 1 ratio predominantly in males and there are multiple factors responsible
00:25for this and there are threefold, one is genetics and the second one is epigenetics and the third
00:32one is hormonal which I will be explaining.
00:36So coming to the first part, the genetics part which is the most important differentiation
00:40between male and female and the females have two X chromosomes and the males have one X
00:46chromosome and this is called female protection.
00:50As we know, the autism genetic disorders, the genes are mostly transferred through the
00:56X chromosome.
00:57So the concentration of the pathogenic disease-causing genes to cause disease in females needs to
01:05be higher because of the two X chromosomes.
01:10As males have only one X chromosome, the burden is essentially much lower.
01:14So this mechanism is called female protection in the sense they are more protected towards
01:20autism.
01:21And the second one, because males have only one X chromosome and the de novo mutation, even
01:27though there is no family history, de novo mutation for a male child to get autism from a de novo
01:35mutation, the load needed for that mutation is very low compared to females because they carry
01:43only one X chromosome and other genetic disorders like shank 3 gene and nrx n1 gene and even though
01:52they are present in both males and females, but they are more penetrant, the penetrance means
01:57presence of disease mutation causing disease clinically.
02:01So it's called penetration.
02:04So the pathogenic genes which are responsible for the disease have more penetrance in males
02:09compared to females.
02:12And the second part is called epigenetic mechanism and which is very important and there is something
02:19called gene inactivation or mosaic inactivation.
02:23So if you see the X chromosome in all the males, they come from the mother and the Y chromosome
02:30comes from the father.
02:31So in mosaic inactivation, what happens is even though there are two X chromosomes, so because
02:37they are similar, one of them gets inactivated.
02:40That's called gene inactivation.
02:41In most of the times, the mutated X gene because of lack of function and they get deactivated.
02:48Whereas the normal X gene, so it gets activated and it becomes functional.
02:53So the inactivated gene, if it's transferred to the next generation male, they can express
02:59the autism.
03:00And whereas the females, because they have two X chromosome, one from the father and one
03:04from the mother.
03:05So even though one of them carries the X chromosome, the genes responsible for the autism, the other
03:10one cancels it out.
03:11This is called mosaic inactivation of the X chromosome and it is an epigenetic mechanism
03:16which is also responsible for increased influence in male babies.
03:22And the third part is the hormonal part.
03:25So as we know, the testosterone in the, because of the adrenal glands in male babies and they
03:34produce testosterone and even before birth.
03:37So what happens is the male babies, they express more receptors which are androgen receptors
03:45in their brains before the birth.
03:47And whereas female babies, they actually, they express receptors which are more receptive
03:54to estrogens, female hormones before birth.
03:57So the difference is even before the birth.
04:00In the sense that the male babies, because of the exposure to testosterone inside the brain,
04:09so they tend to have less oxytocin which is responsible for empathy and social bonding.
04:15So as we know, oxytocin is also called happy hormone or bonding hormone, which is responsible
04:21for the mother and which comes while the mother gives the milk to the baby.
04:27So it is one of the most gratifying things in the life of the mother.
04:33And these things do contribute.
04:36So because of the increase of prenatal testosterone, before birth testosterone exposure to the male
04:41babies, so there will be less oxytocin resulting in less social bonding and which results in
04:49less empathy and so forth and then it results in more risk of autism.
04:55So there is one, this is, can be seen in the patients in male babies born with adrenal hyperplasia
05:01where there is increased levels of testosterone hormone of production and where there is
05:06they have very much high risk of getting autism spectrum compared to this.
05:12And apart from that, there are certain environmental factors also, so which can respond, which can
05:18cause, contribute to this.
05:20And as male babies, they are more prone to systematism, that's called rules-based learning.
05:28And whereas female babies, they are more into social interactions.
05:31And in a troubled family, and where there is a single parent or the parents are going through
05:38a difficult phase, so the risk on male babies is much higher to withdraw, in the sense that
05:46they have more risk of getting autism compared to the female child.
05:50And that's the same way.
05:56You
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