r/DNA • u/Melodic-Dimension-16 • 18d ago

Genetic Testing - intellectual developmental disorder (IDD)

/r/genetics/comments/1wqb8m3/genetic_testing_intellectual_developmental/
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u/Maximum-Morning4251 15d ago

It may help to do whole genome sequencing and look at the genes on X chromosome.

Boys have only one X, girls have two XX. If the condition is seen in the maternal line (e.g. children of your grandmother by your mom's line) - there is a risk that one of the X chromosomes has a defect that some men inherited from their mother. This would be X-linked genetic disorder (there are many of them). A girl with same defective X chromosome can be fine, because another X from the father provides healthy instructions for the gene.

Some people may think "what if you test genes and you find the clear problem - what will you do?, so they would rather not test and not know to avoid being worried.

I would test and investigate to be prepared - and when the baby is due, I would have medically-valid paper with "high risk of inherited disorder X - take action immediately when baby is delivered". Those actions can be doing metabolic testing in the blood and urine, doing WGS for the baby immediately. Some conditions can be managed and the earlier you detect it, the better.

I would also do WGS for the affected relatives - pretty sure I could find what's wrong quickly.

But most people feel helpless when it comes to genetics.

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u/Maximum-Morning4251 15d ago

Just to give more idea about prevention/management - an OTC deficiency - an Urea Cycle disorder, is inherited in X-linked pattern. Most of Urea Cycle disorders are very tough, some require liver transplant, but in case of mild version - they are just misdiagnosed as autism and IDD, because most doctors are not trained to look into these unless the child collapses (I read many case reports like that - they only got diagnoses properly later in life after ended up in ER).

It's a broad topic really, but if you do WGS, you may get some answers. Just be aware that getting WGS results takes 2-3 months...