SYNGAP1-related intellectual disability is a neurological disorder characterized by moderate to severe intellectual disability that is evident in early childhood. The earliest features are typically delayed development of speech and motor skills, such as sitting, standing, and walking. Many people with this condition have weak muscle tone (hypotonia), which contributes to the difficulty with motor skills. Some affected individuals lose skills they had already acquired (developmental regression). Other features of SYNGAP1-related intellectual disability include recurrent seizures (epilepsy), hyperactivity, and autism spectrum disorder, which is characterized by impaired communication and social interaction; almost everyone with SYNGAP1-related intellectual disability develops epilepsy, and about half have autism spectrum disorder.

SYNGAP1-related intellectual disability is a relatively common form of cognitive impairment. It is estimated to account for 1 to 2 percent of intellectual disability cases.

SYNGAP1-related intellectual disability is caused by mutations in the SYNGAP1 gene. The protein produced from this gene, called SynGAP, plays an important role in nerve cells in the brain. It is found at the junctions between nerve cells (synapses) and helps regulate changes in synapses that are critical for learning and memory. Mutations involved in this condition prevent the production of functional SynGAP protein from one copy of the gene, reducing the protein's activity in cells. Studies show that a reduction of SynGAP activity can have multiple effects in nerve cells, including pushing synapses to develop too early. The resulting abnormalities disrupt the synaptic changes in the brain that underlie learning and memory, leading to cognitive impairment and other neurological problems characteristic of SYNGAP1-related intellectual disability.

Genetic Testing Information

• Genetic Testing Registry: Intellectual disability, autosomal dominant 5

Genetic and Rare Diseases Information Center

• Intellectual developmental disorder, autosomal dominant 5

Patient Support and Advocacy Resources

• National Organization for Rare Disorders (NORD)

Clinical Trials

• ClinicalTrials.gov

Catalog of Genes and Diseases from OMIM

• INTELLECTUAL DEVELOPMENTAL DISORDER, AUTOSOMAL DOMINANT 5; MRD5

Scientific Articles on PubMed

• PubMed

• Aceti M, Creson TK, Vaissiere T, Rojas C, Huang WC, Wang YX, Petralia RS, Page DT, Miller CA, Rumbaugh G. Syngap1 haploinsufficiency damages a postnatal critical period of pyramidal cell structural maturation linked to cortical circuit assembly. Biol Psychiatry. 2015 May 1;77(9):805-15. doi: 10.1016/j.biopsych.2014.08.001. Epub 2014 Aug 13. Citation on PubMed or Free article on PubMed Central
• Clement JP, Aceti M, Creson TK, Ozkan ED, Shi Y, Reish NJ, Almonte AG, Miller BH, Wiltgen BJ, Miller CA, Xu X, Rumbaugh G. Pathogenic SYNGAP1 mutations impair cognitive development by disrupting maturation of dendritic spine synapses. Cell. 2012 Nov 9;151(4):709-723. doi: 10.1016/j.cell.2012.08.045. Citation on PubMed or Free article on PubMed Central
• Clement JP, Ozkan ED, Aceti M, Miller CA, Rumbaugh G. SYNGAP1 links the maturation rate of excitatory synapses to the duration of critical-period synaptic plasticity. J Neurosci. 2013 Jun 19;33(25):10447-52. doi: 10.1523/JNEUROSCI.0765-13.2013. Citation on PubMed or Free article on PubMed Central
• Mignot C, von Stulpnagel C, Nava C, Ville D, Sanlaville D, Lesca G, Rastetter A, Gachet B, Marie Y, Korenke GC, Borggraefe I, Hoffmann-Zacharska D, Szczepanik E, Rudzka-Dybala M, Yis U, Caglayan H, Isapof A, Marey I, Panagiotakaki E, Korff C, Rossier E, Riess A, Beck-Woedl S, Rauch A, Zweier C, Hoyer J, Reis A, Mironov M, Bobylova M, Mukhin K, Hernandez-Hernandez L, Maher B, Sisodiya S, Kuhn M, Glaeser D, Weckhuysen S, Myers CT, Mefford HC, Hortnagel K, Biskup S; EuroEPINOMICS-RES MAE working group; Lemke JR, Heron D, Kluger G, Depienne C. Genetic and neurodevelopmental spectrum of SYNGAP1-associated intellectual disability and epilepsy. J Med Genet. 2016 Aug;53(8):511-22. doi: 10.1136/jmedgenet-2015-103451. Epub 2016 Mar 17. Citation on PubMed
• Ozkan ED, Creson TK, Kramar EA, Rojas C, Seese RR, Babyan AH, Shi Y, Lucero R, Xu X, Noebels JL, Miller CA, Lynch G, Rumbaugh G. Reduced cognition in Syngap1 mutants is caused by isolated damage within developing forebrain excitatory neurons. Neuron. 2014 Jun 18;82(6):1317-33. doi: 10.1016/j.neuron.2014.05.015. Citation on PubMed or Free article on PubMed Central
• Parker MJ, Fryer AE, Shears DJ, Lachlan KL, McKee SA, Magee AC, Mohammed S, Vasudevan PC, Park SM, Benoit V, Lederer D, Maystadt I, Study D, FitzPatrick DR. De novo, heterozygous, loss-of-function mutations in SYNGAP1 cause a syndromic form of intellectual disability. Am J Med Genet A. 2015 Oct;167A(10):2231-7. doi: 10.1002/ajmg.a.37189. Epub 2015 Jun 15. Citation on PubMed or Free article on PubMed Central
• Wang CC, Held RG, Hall BJ. SynGAP regulates protein synthesis and homeostatic synaptic plasticity in developing cortical networks. PLoS One. 2013 Dec 31;8(12):e83941. doi: 10.1371/journal.pone.0083941. eCollection 2013. Citation on PubMed or Free article on PubMed Central