The  diagnosis of FAS requires 3 criteria:
1.   3 specific facial abnormalities.
2.   Growth problems.
3.   Central nervous system (CNS) problems.
 
1.   The 3 abnormal facial features are: 1) Smooth ridge between the nose and upper lip (smooth philtrum),  2) Thin upper lip and 3) short distance between the inner and outer corners of the eyes which gives the eyes a wide spaced appearance.
( see the lip-philtrum guide at:
http://depts.washington.edu/fasdpn/htmls/lip-philtrum-guides.htm
 
 
Other features that can be seen are a low nasal bridge, short nose and a small head circumference.
 
2. Growth problems: Confirmed prenatal or postnatal height or weight at or  both below the 10th percentile.  Adjusted for age, gestational age and race.
 
3. Central nervous system abnormalities: (includes any of the following)
 
a) Head circumference at or below the 10th percentile adjusted for age and sex and/ or clinically significant brain abnormalities observed through imaging
 
.
 
b) Neurological-problems with abnormal nervous system function that cannot be linked to another cause including poor coordination and muscle control or problems is sucking as a baby.
 
 
 
 c) Functional problems including:
 
 Global cognitive or intellectual deficits with performance below the third percentile or functional deficits below the 16th percentile in three of the following: cognitive or developmental deficits, executive functioning deficits, motor functioning delays, problems with attention or hyper activity, impaired social skills, and other problems such as sensor, language or memory deficits.
 
Mother’s alcohol use during pregnancy can strengthen the case for a FAS diagnosis but it is not essential if the child meets the criteria above. 
 
The symptom pattern can overlap with other disorders such as Fragile X Syndrome, but is distinct from other disorders such as Tuberosis Sclerosis and Prader-Willi Syndrome.  Other diagnostic measures can help discriminate conditions with overlapping symptom patterns.