The symptoms associated with this syndrome are variable, but common features include: low birthweight, low muscle tone at birth, poor feeding in infancy (often requiring feeding by tube for a period) and oromotor dyspraxia together with moderate developmental delays and learning disabilities but amiable behaviour. Other clinically important features include epilepsy, heart defects (atrial septal defect, ventricular septal defect) and kidney/urological anomalies. Silvery depigmentation of strands of hair have been noted in several patients. With age there is an apparent coarsening of facial features. 17q21.3 was reported simultaneously in 2006 by three independent groups, with each group reporting several patients, and is now recognised to be one of the more common recurrent microdeletion syndromes. Recently a patient with a small duplication in same segment of DNA has been described. An overview of the clinical features of the syndrome, by reviewing 22 individuals with a 17q21.31 microdeletion, estimated the disorder is present in one in every 16,000 people.
The recurrent deletion is between 500-650 kilobases (Kb) in size encompassing at least six genes, among them the microtubule-associated protein tau (MAPT). A review of five patients found the parental chromosome from which the deletion originated carried a common 900kb inversion polymorphism. The orientation of low copy repeats flanking the deleted segment, suggests the inversion in the parental chromosome influences the deletion in the child's chromosome via a non-allelic homologous recombination (NAHR) mechanism.
^ abSharp AJ, Hansen S, Selzer RR et al. (September 2006). "Discovery of previously unidentified genomic disorders from the duplication architecture of the human genome". Nat. Genet.38 (9): 1038–42. doi:10.1038/ng1862. PMID16906162.
^ abShaw-Smith C, Pittman AM, Willatt L, Martin H, Rickman L, Gribble S, Curley R, Cumming S, Dunn C, Kalaitzopoulos D, Porter K, Prigmore E, Krepischi-Santos AC, Varela MC, Koiffmann CP, Lees AJ, Rosenberg C, Firth HV, de Silva R, Carter NP (2006). "Microdeletion encompassing MAPT at chromosome 17q21.3 is associated with developmental delay and learning disability.". Nat Genet38 (9): 1032–7. doi:10.1038/ng1858. PMID16906163.
^ abKoolen DA, Vissers LE, Pfundt R, de Leeuw N, Knight SJ, Regan R, Kooy RF, Reyniers E, Romano C, Fichera M, Schinzel A, Baumer A, Anderlid BM, Schoumans J, Knoers NV, van Kessel AG, Sistermans EA, Veltman JA, Brunner HG, de Vries BB (2006). "A new chromosome 17q21.31 microdeletion syndrome associated with a common inversion polymorphism.". Nat Genet38 (9): 999–1001. doi:10.1038/ng1853. PMID16906164.
^ abcKoolen DA, Sharp AJ, Hurst JA, Firth HV, Knight SJ, Goldenberg A, Saugier-Veber P, Pfundt R, Vissers LE, Destrée A, Grisart B, Rooms L, Van der Aa N, Field M, Hackett A, Bell K, Nowaczyk MJ, Mancini GM, Poddighe PJ, Schwartz CE, Rossi E, De Gregori M, Antonacci-Fulton LL, McLellan MD, Garrett JM, Wiechert MA, Miner TL, Crosby S, Ciccone R, Willatt L, Rauch A, Zenker M, Aradhya S, Manning MA, Strom TM, Wagenstaller J, Krepischi-Santos AC, Vianna-Morgante AM, Rosenberg C, Price SM, Stewart H, Shaw-Smith C, Brunner HG, Wilkie AO, Veltman JA, Zuffardi O, Eichler EE, de Vries BB (2008). "Clinical and molecular delineation of the 17q21.31 microdeletion syndrome.". J Med Genet45 (11): 710–20. doi:10.1136/jmg.2008.058701. PMC3071570. PMID18628315.
^Tan TY, Aftimos S, Worgan L, Susman R, Wilson M, Ghedia S, Kirk EP, Love D, Ronan A, Darmanian A, Slavotinek A, Hogue J, Moeschler JB, Ozmore J, Widmer R, Bruno D, Savarirayan R, Peters G (2009). "Phenotypic expansion and further characterisation of the 17q21.31 microdeletion syndrome.". J Med Genet46 (7): 480–9. doi:10.1136/jmg.2008.065391. PMID19447831.
^Varela MC, Krepischi-Santos AC, Paz JA, Knijnenburg J, Szuhai K, Rosenberg C, Koiffmann CP (2006). "A 17q21.31 microdeletion encompassing the MAPT gene in a mentally impaired patient.". Cytogenet Genome Res114 (1): 89–92. doi:10.1159/000091934. PMID16717456.
^Sharkey FH, Morrison N, Murray R, Iremonger J, Stephen J, Maher E, Tolmie J, Jackson AP (2009). "17q21.31 microdeletion syndrome: further expanding the clinical phenotype.". Cytogenet Genome Res127 (1): 61–6. doi:10.1159/000279260. PMID20110647.
^Kirchhoff M, Bisgaard AM, Duno M, Hansen FJ, Schwartz M (2007). "A 17q21.31 microduplication, reciprocal to the newly described 17q21.31 microdeletion, in a girl with severe psychomotor developmental delay and dysmorphic craniofacial features". Eur J Med Genet50 (4): 256–63. doi:10.1016/j.ejmg.2007.05.001. PMID17576104.