GN 301 Module 7: Intellectual Disabilities

St Thomas Aquinas

________ defined intelligence as the ability to combine and separate.

IQ is assumed to be distributed as a ____ distribution

normal

What is the average IQ?

100

What is the normal range of IQ? 

85-115

IQ below __**__**__ is considered intellectually disabled

70

About __ of the population falls in the intellectually disabled range

3%

Single gene examples

Simple Mendelian

PKU (autosomal recessive)

Cannot properly metabolize phenylalanine

Galactosemia  (autosomal recessive)

Toxic levels of galactose in blood

Hurler Syndrome (autosomal recessive)

* Missing lysozomal enzyme allows chemical buildup leading to neurological degeneration
* Often death by age 10
* Enzyme therapy

Tay-Sachs Disease (autosomal recessive)

* inherited lysosomal storage disorder – missing enzyme
* fatty substance builds up in the brain and destroys nerve tissue
* Convulsions, blindness, paralysis, death usually by 5 yrs

Rett Syndrome

(X-linked dominant)

Polygenic:

Possible to get the “bad luck” alleles of several polygenes that contribute to intelligence

See familial inheritance patterns of some intellectual disabilities. More than ___ of cases come from less than 10% of families

__75%__

If both parents have IQ values in the 50 – 70 range, there is a 60-70% chance that their child will also have a subnormal intelligence

Trisomic Situations

* **Trisomy 21 (Down Syndrome)**
* **Trisomy 18 (Edward Syndrome).**
* 50% die in utero Of those who live, 90% will not live longer than 1 yr.
* About 1 in 6000 live births 
* **Trisomy 13 (Patau Syndrome).**
* 1 in 12,000 live births
* **Fragile X Syndrome.**
* Many copies of repeated CGG sequence 
* **William Syndrome.**
* Deletion of 26 genes on chr #7

* **Trisomy 18 (Edward Syndrome).**

* 50% die in utero Of those who live, 90% will not live longer than 1 yr.
* About 1 in 6000 live births 

* **Trisomy 13 (Patau Syndrome).**

\

* 1 in 12,000 live births

Prenatal:

pre-birth health conditions

* Infections (measles, malaria, HIV, herpes)
* Small enough to get to fetus through placenta
* Medicines, Drugs, Alcohol, Smoking
* Maternal Health
* High Blood Pressure
* Diabetes
* Nutrition

Perinatal:

at delivery

* oxygen deprivation at delivery is the main cause from environmental factors
* Premature delivery (low birth weight) (<5.5 pounds)
* Low birth weight correlated with lower IQ

Preterm vs Premature

"Preterm" is a medical term used by healthcare professionals to refer to a baby that is born before the 37th week of pregnancy, regardless of whether the baby is born early or not.

"Premature," on the other hand, is a more general term that refers to any baby that is born before the due date, regardless of how early they are born. In other words, a baby that is born at 36 weeks would be considered preterm, but not necessarily premature, while a baby that is born at 32 weeks would be considered both preterm and premature.

Postnatal:

after delivery

* early nutrition is critical!
* Protein deficiency causes damage to central nervous system