M Mahdi Motazacker

Publications of M Mahdi Motazacker

• Mutations in NSUN2 Cause Autosomal- Recessive Intellectual Disability.

  Authors: Lia Abbasi-Moheb, Sara Mertel, Melanie Gonsior, Leyla Nouri-Vahid, Kimia Kahrizi, Sebahattin Cirak, Dagmar Wieczorek, M Mahdi Motazacker, Sahar Esmaeeli-Nieh, Kirsten Cremer, Robert Weißmann, Andreas Tzschach, Masoud Garshasbi, Seyedeh S Abedini, Hossein Najmabadi, H Hilger Ropers, Stephan J Sigrist, Andreas W Kuss

  American journal of human genetics. 04/2012;

  With a prevalence between 1 and 3%, hereditary forms of intellectual disability (ID) are among the most important problems in health care. Particularly, autosomal-recessive forms of the disorder haveWith a prevalence between 1 and 3%, hereditary forms of intellectual disability (ID) are among the most important problems in health care. Particularly, autosomal-recessive forms of the disorder have a very heterogeneous molecular basis, and genes with an increased number of disease-causing mutations are not common. Here, we report on three different mutations (two nonsense mutations, c.679C>T [p.Gln227(∗)] and c.1114C>T [p.Gln372(∗)], as well as one splicing mutation, g.6622224A>C [p.Ile179Argfs(∗)192]) that cause a loss of the tRNA-methyltransferase-encoding NSUN2 main transcript in homozygotes. We identified the mutations by sequencing exons and exon-intron boundaries within the genomic region where the linkage intervals of three independent consanguineous families of Iranian and Kurdish origin overlapped with the previously described MRT5 locus. In order to gain further evidence concerning the effect of a loss of NSUN2 on memory and learning, we constructed a Drosophila model by deleting the NSUN2 ortholog, CG6133, and investigated the mutants by using molecular and behavioral approaches. When the Drosophila melanogaster NSUN2 ortholog was deleted, severe short-term-memory (STM) deficits were observed; STM could be rescued by re-expression of the wild-type protein in the nervous system. The humans homozygous for NSUN2 mutations showed an overlapping phenotype consisting of moderate to severe ID and facial dysmorphism (which includes a long face, characteristic eyebrows, a long nose, and a small chin), suggesting that mutations in this gene might even induce a syndromic form of ID. Moreover, our observations from the Drosophila model point toward an evolutionarily conserved role of RNA methylation in normal cognitive development.

• ST3GAL3 mutations impair the development of higher cognitive functions.

  Authors: Hao Hu, Katinka Eggers, Wei Chen, Masoud Garshasbi, M Mahdi Motazacker, Klaus Wrogemann, Kimia Kahrizi, Andreas Tzschach, Masoumeh Hosseini, Ideh Bahman, Tim Hucho, Martina Mühlenhoff, Rita Gerardy-Schahn, Hossein Najmabadi, H Hilger Ropers, Andreas W Kuss

  American journal of human genetics. 09/2011; 89(3):407-14.

  The genetic variants leading to impairment of intellectual performance are highly diverse and are still poorly understood. ST3GAL3 encodes the Golgi enzyme β-galactoside-α2,3-sialyltransferase-IIIThe genetic variants leading to impairment of intellectual performance are highly diverse and are still poorly understood. ST3GAL3 encodes the Golgi enzyme β-galactoside-α2,3-sialyltransferase-III that in humans predominantly forms the sialyl Lewis a epitope on proteins. ST3GAL3 resides on chromosome 1 within the MRT4 locus previously identified to associate with nonsyndromic autosomal recessive intellectual disability. We searched for the disease-causing mutations in the MRT4 family and a second independent consanguineous Iranian family by using a combination of chromosome sorting and next-generation sequencing. Two different missense changes in ST3GAL3 cosegregate with the disease but were absent in more than 1000 control chromosomes. In cellular and biochemical test systems, these mutations were shown to cause ER retention of the Golgi enzyme and drastically impair ST3Gal-III functionality. Our data provide conclusive evidence that glycotopes formed by ST3Gal-III are prerequisite for attaining and/or maintaining higher cognitive functions.