Endele et al. (2010) reported 2 unrelated German boys with mental retardation associated with 2 different de novo chromosome translocations, t(9;12)(p23;p13.1) and t(10;12)(q21.1;p13.1), respectively, with a common breakpoint in 12p13.1 that disrupted the GRIN2B gene. The first boy ... Endele et al. (2010) reported 2 unrelated German boys with mental retardation associated with 2 different de novo chromosome translocations, t(9;12)(p23;p13.1) and t(10;12)(q21.1;p13.1), respectively, with a common breakpoint in 12p13.1 that disrupted the GRIN2B gene. The first boy had mild to moderate mental retardation, behavioral anomalies, and abnormal electroencephalogram (EEG), whereas the second boy had a more complex phenotype including severe mental retardation, behavioral and EEG anomalies, ophthalmologic manifestations, choanal atresia, cryptorchidism, and flat feet. Neither had overt seizures. Endele et al. (2010) also reported 4 unrelated patients of European descent with nonsyndromic mild to moderate mental retardation. One of the patients also had irregular slow dysrhythmia on EEG, but none showed seizures. All had behavioral abnormalities that were not specifically delineated.
In 4 of 468 patients with mental retardation, Endele et al. (2010) identified 4 different de novo heterozygous mutations in the GRIN2B gene (138252.0001-138252.0004).
By sequencing 44 candidate genes in 2,446 autism spectrum disorder probands, O'Roak ... In 4 of 468 patients with mental retardation, Endele et al. (2010) identified 4 different de novo heterozygous mutations in the GRIN2B gene (138252.0001-138252.0004). By sequencing 44 candidate genes in 2,446 autism spectrum disorder probands, O'Roak et al. (2012) identified 4 individuals with de novo mutations in the GRIN2B gene. The mutations included a frameshift, a missense, a splice site, and a nonsense mutation (138252.0005-138252.0008).