|Bruno and colleagues identified two classes of co-locating microduplications in 17p13.3: class I duplications including YWHAE but not PAFAH1B1; and class II duplications always including PAFAH1B1, and sometimes including the genomic region encompassing the CRK and YWHAE genes . Class I microduplications are associated with intellectual disability (ID), subtle dysmorphic facial features, subtle hand/foot malformations, and a tendency toward postnatal overgrowth . Class II microduplications recently have been shown to be associated with mild to moderate ID and hypotonia. Some dysmorphic features, such as prominent forehead and pointed chin, are shared with class I duplications, while overgrowth, behavioural problems and hand/foot abnormalities are less often noted.
 Bruno D L, Anderlid B M, Lindstrand A, van Ravenswaaij-Arts C, Ganesamoorthy D, Lundin J, Martin C L, Douglas J, Nowak C, Adam M P, Kooy R F, Van der Aa N, et al. Further molecular and clinical delineation of co-locating 17p13.3 microdeletions and microduplications that show distinctive phenotypes. J Med Genet 47:299-311
|We suggest that there are two classes of co-locating microduplications in 17p13.3. Class I duplications (six cases) involve YWHAE (encoding 14-3-3e), but notably not PAFAH1B1.12 Class II duplications (seven cases) always involve PAFAH1B1 and may also include the genomic region encompassing the CRK and YWHAE genes.12 14 Class I show autistic manifestations and other behavioural symptoms, speech and motor delay, subtle dysmorphic facial features, subtle hand/foot malformations, and a tendency to postnatal overgrowth (table 2). Class II microduplications have recently been shown to be associated with moderate to mild developmental and psychomotor delay and hypotonia. Some dysmorphic features, such as prominent forehead and pointed chin, are shared with the class I duplications, while overgrowth, behavioural problems and hand/foot abnormalities are less often noted (table 3).
12. Bi W, Sapir T, Shchelochkov OA, Zhang F, Withers MA, Hunter JV, Levy T, Shinder V, Peiffer DA, Gunderson KL, Nezarati MM, Shotts VA, Amato SS, Savage SK, Harris DJ, Day-Salvatore DL, Horner M, Lu XY, Sahoo T, Yanagawa Y, Beaudet AL, Cheung SW, Martinez S, Lupski JR, Reiner O. Increased LIS1 expression affects human and mouse brain development. Nat Genet 2009;41:168e77.
14. Roos L, Jonch AE, Kjaergaard S, Taudorf K, Simonsen H, Hamborg-Petersen B, Brondum-Nielsen K, Kirchhoff M. A new microduplication syndrome encompassing the region of the Miller-Dieker (17p13 deletion) syndrome. J Med Genet 2009;46:703e10.