Watson syndrome: isita subtype oftype1 neurofibromatosi s?

Over20yearsago,Watsondescribed three families witha condition characterised by pulmonaryvalvularstenosis, caf6au lait patches, anddullintelligence. Shortstature is anadditional feature ofthisautosomal dominantcondition. A fourthfamilywithWatson syndromehassincebeenreported. We have hadtheopportunity toreviewmembersof threeof thesefourfamilies. The clinical phenotypeof Watsonsyndromehas been expandedtoinclude relative macrocephaly andLischnodules inthemajority ofaffected subjects, andneurofibromas inone-third of familymembers.Becausetheadditional clinicalfindings enhancethesimilarity between Watsonsyndromeandneurofibromatosis 1, molecularlinkagestudies havebeenperformedusingprobesflanking theNFIgeneon chromosome17.ProbeHHH202showedthe tightest linkage toWatsonsyndromewitha maximum lodscoreof359at0=00 (95% confidence limits of0=0-0-0. 15). Thissuggests either thatWatsonsyndromeandneurofibromatosis 1areallelic, orthatthereisaseries of