Step I Down syndrome Vs fragile X

[Dr.serotonin]

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they say (UW) that the most common inherited cause of intellectual disability is Fragile X syndrome and the most common congenital cause of intellectual disability is Down syndrome. what is the difference between congenital and inherited ?? Isn't down inherited?

 

[chillaxbro]

This is how I see it: Inherited means you can pass it down. Congenital just means you're born with it so it may or may not be inherited

Down syndrome you're just kind of born with due to something going wrong in cell biology / meiosis. Its genetic in origin but I dont think you can pass it down

 

[worldbeater]

Down syndrome you're just kind of born with due to something going wrong in cell biology / meiosis. Its genetic in origin but I dont think you can pass it down

Also remember with Down's syndrome, the #1 cause is nondisjunction, 2) robertsonian translocation 3) mosacisim

 

[Dr.serotonin]

Down syndrome you're just kind of born with due to something going wrong in cell biology / meiosis. Its genetic in origin but I dont think you can pass it down

are you sure a Down synd patient can't pass it to the offsprings? i guess why not? during gametogenesis one of the sperm?oocyte may get that extra 21 chromosome (even if nondysjunction do not occur)

 

[chillaxbro]

are you sure a Down synd patient can't pass it to the offsprings? i guess why not? during gametogenesis one of the sperm?oocyte may get that extra 21 chromosome (even if nondysjunction do not occur)

True...... no I'm not sure

 

[zhopv10]

They can if its from a robertsonian translocation, not sure if they can otherwise...might increase the risk, I'll have to look they up.


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[Jabbed]

are you sure a Down synd patient can't pass it to the offsprings? i guess why not? during gametogenesis one of the sperm?oocyte may get that extra 21 chromosome (even if nondysjunction do not occur)

Males with Down syndrome are infertile (trisomic spermatogonia are non-viable). Female with down syndrome have decreased fertility, rarely reproduce, but can pass on the trisomy. Still, this scenario is far less common the Fragile X from an epidemiologic level.

 

[worldbeater]

Also in order of frequency: 1) Fetal alcohol syndrome 2) Fragile X 3) Down's Syndrome

Everybody things Down's is the most common out of the three, but these two conditions are ahead of it.

 

[aspiringmd1015]

just made a thread on this and didnt realize this one. So basically fragile X is more common bc of the rare Robertosonian causes of Downs, and also bc males are infertile?

how does CGG repeates cause FMR1 hypermethylation??

 

[slz1900]

Also in order of frequency: 1) Fetal alcohol syndrome 2) Fragile X 3) Down's Syndrome

Everybody things Down's is the most common out of the three, but these two conditions are ahead of it.

Where'd you see this? CDC says that Down syndrome is more common than fragile X.

 

[slz1900]

just made a thread on this and didnt realize this one. So basically fragile X is more common bc of the rare Robertosonian causes of Downs, and also bc males are infertile?

how does CGG repeates cause FMR1 hypermethylation??

Right, Fragile X is by definition inherited, Down syndrome by definition isn't except for Robertsonian translocation. As for fertility, here's at least 1 case report of a male having children. Since literally no resource discusses Down syndrome fertility I wouldn't worry about it. CGG repeats are in the promoter region. and CpG islands are what are methylated to silence genes and if you have a lot more of them you will have a greater silencing of gene expression.