Partial deletion of GLRB and GRIA2 in a patient with intellectual disability.
We report about the partial de novo loss of GLRB and GRIA2 in an individual with intellectual disability (ID). No additional mutations were found in either gene. GLRB itself does not seem to be a good candidate as it causes autosomal recessive hyperekplexia and no symptoms were found in the patient. Mutations of GRIA2 have not been described as cause of ID to date. Nonetheless, it is a very attractive candidate because it encodes a subunit of a glutamate receptor, which is highly expressed in postsynaptic structures and has an important role in signal transduction across synapses. Although we were able to isolate a fragment of a fusion transcript of both genes from the patient's blood, we were not able to isolate a transcript with an open reading frame throughout the entire length. The reading frame could be restored by differential splicing, which might take place in brain tissue but not in blood. We assume that either haploinsufficiency of GRIA2 or a GLRB/GRIA2 fusion gene leading to a protein with dominant-negative properties is causing the phenotype of the patient.
Institut für Klinische Genetik, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany. karl.hackmann@tu-dresden.de
Karl
K
Hackmann
Sarah
S
Matko
Eva-Maria
EM
Gerlach
Maja
M
von der Hagen
Barbara
B
Klink
Evelin
E
Schrock
Andreas
A
Rump
Nataliya
N
Di Donato
D000595:Amino Acid Sequence; D002675:Child, Preschool; D005091:Exons; D050939:Gene Fusion; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008607:Intellectual Disability / Q000235:genetics*; D008297:Male; D008969:Molecular Sequence Data; D018091:Receptors, AMPA / Q000235:genetics*; D018009:Receptors, Glycine / Q000235:genetics*; D017384:Sequence Deletion
C114561:GLRB protein, human; D018091:Receptors, AMPA; D018009:Receptors, Glycine; C104722:glutamate receptor ionotropic, AMPA 2