A NOVEL PHENOTYPIC PATTERN IN X-LINKED INHERITANCE - CRANIOFRONTONASAL SYNDROME MAPS TO XP22

Craniofrontonasal syndrome (CFNS, OMIM 304110) is a distinctive geneti c disorder whose main clinical manifestations include coronal synostos is, widely spaced eyes, clefting of the nasal tip and various skeletal anomalies. CFNS originally was thought to be transmitted as an autoso mal dominant trait, but recent studies suggest that it is X-linked dom inant, whereby all daughters of males are affected, whereas none of th eir sons are affected. Here we report data confirming that CFNS is X-l inked, mapping to a 13 cM interval in Xp22 with a maximum two-point lo d score of 3.9 (theta = 0) at DXS8022 and a multipoint lod score of 5. 08 at DXS1224. Detailed phenotypic analysis shows that females are mor e severely affected than males, a highly unusual characteristic for an X-linked disorder. CFNS represents the first multiple congenital anom aly syndrome with this unusual phenotypic pattern of X-linked inherita nce.