The different diagnostic schemas all agree on the facial characteristics used to define FAS but differ in how many must be present to obtain a diagnosis. The most distinctive facial characteristics are short palpebral fissures, a smooth philtrum, and a thin upper vermillion border (Fig. 1). In all four schemas, growth deficiency for FAS is defined as pre or postnatal weight or height at or below the 10th percentile. The CNS dysfunction has the broadest range of potential deficits and is the most variable among the different schemas, but is most consistently defined as evidence of a structural brain anomaly, head circumference below the 10th percentile, or evidence of pervasive neurological or other CNS dysfunction.
