Developmental pathogenesis of short palpebral fissure length in children with fetal alcohol syndrome.

BACKGROUND: From the standpoint of normal embryologic development, the palpebral fissures are generally considered to be determined by and dependent on the underlying optic vesicles, outpouchings of the frontal area of the developing fetal brain. It has been suggested that short palpebral fissures are a reflection of an underlying defect in specific areas of forebrain development. Alternatively, short palpebral fissures, seen in a number of multiple malformation syndromes associated with small occipitofrontal circumference (OFC), such as the fetal alcohol syndrome (FAS), might be proportionally small as a reflection of the microcephaly. The purpose of this study was to examine whether short palpebral fissures are independent of or determined by the OFC.
METHODS: Age-specific palpebral fissure length (PFL) and OFC centiles were correlated in 273 children with FAS, 272 children with some features of FAS, and 385 children with no structural features characteristic of FAS.
RESULTS: The OFC and PFL centiles demonstrated a statistically significant but weak correlation in all three study groups. Among children with FAS, only 10.2% of the total variation in PFL could be accounted for by OFC (p = 0.0001). A similar pattern was observed for children with some features of FAS (r(2) = 0.142; p = 0.0001) and children with no structural features of FAS (r(2) = 0.110; p = 0.0001).
CONCLUSIONS: Palpebral fissure length is predominately independent of occipitofrontal circumference in children with and without features of FAS. Short palpebral fissures may well reflect a defect in forebrain development rather than being proportionally reduced in size as a reflection of microcephaly. Birth Defects Research (Part A) 2009. (c) 2009 Wiley-Liss, Inc.