1. Genetic Disorders
Fragile-X Syndrome (FXS)
Prevalence
Approximately 1 in 5000 births
1 in 4000 for males, 1 in 6000 for females
Why?
In many X linked conditions only males who inherit the abnormal gene are affected (e.g. red-green colour blindness).
Fragile X syndrome is an exception, in that females can also be affected – but prevalence is lower and symptoms are less severe.

2. Premutation versus Full Mutation
“Normal” Persons
A section of the DNA in the FMR1 gene (X chromosome) repeats about 30 times. 
Sequence: cytosine, guanine and guanine (CGG). 
Persons with Premutation
CGG repeats times. 
Persons with Full Mutation
CGG repeats times. 

3. 38 weeks
4 pounds, 13 ounces

4. Small for Gestational Age
More than two standard deviations below expected birth weight for gestation time for preterm and full term babies.
Public Health Agency of Canada:
Can include:
Low birth weight (LBW) < 5.5 pounds
Very low birth weight (VLBW) < 3.3 pounds
Extremely low birth weight (ELBW) < 1.1 pounds

5. Appropriate for Gestational Age (AGA)
Less than 2 standard deviations below expected birth weight for gestation time.
Smaller than 90th percentile of expected birth weight for gestational time.
Can include:
Low birth weight (LBW) < 5.5 pounds
Very low birth weight (VLBW) < 3.3 pounds
Extremely low birth weight (ELBW) < 1.1 pounds