Rundataxin, a novel protein with RUN and diacylglycerol binding domains, is mutant in a new recessive ataxia.
We have identified a novel form of recessive ataxia that segregates in three children of a large consanguineous Saudi Arabian family. The three patients presented with childhood onset gait and limb ataxia, dysarthria and had limited walking without aid into their teenage years. Two patients developed epilepsy at 7 months without relapse after treatment, and mental retardation. Linkage studies allowed us to identify a single locus that segregated with the disease on chromosome 3q28-qter. Mutation screening of all coding sequences revealed a single nucleotide deletion, 2927delC, in exon 19 of the KIAA0226 gene, which results in a frame shift of the C-terminal domain (p.Ala943ValfsX146). The KIAA0226 gene encodes a protein that we named rundataxin, with two conserved domains: an N-terminal RUN domain and a C-terminal domain containing a diacylglycerol binding-like motif. The closest paralogue of rundataxin, the plekstrin homology domain family member M1, has been shown to colocalize with Rab7, a small GTPase associated with late endosomes/lysosomes, suggesting that rundataxin may also be associated with vesicular trafficking and signalling pathways through its RUN and diacylglycerol binding-like domains. The rundataxin pathway appears therefore distinct from the ataxia pathways involving deficiency in mitochondrial or nuclear proteins and broadens the range of mechanisms leading to recessive ataxias.
Assoum
Mirna
M
Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/Université de Strasbourg, et Collège de France, 67404 Illkirch, France.
Salih
Mustafa A
MA
Drouot
Nathalie
N
H'Mida-Ben Brahim
Dorra
D
Lagier-Tourenne
Clotilde
C
AlDrees
Abdulmajeed
A
Elmalik
Salah A
SA
Ahmed
Taha S
TS
Seidahmed
Mohammad Z
MZ
Kabiraj
Mohammad M
MM
Koenig
Michel
M
D000293:Adolescent; D001259:Ataxia / Q000235:genetics* / Q000473:pathology; D000071183:Autophagy-Related Proteins; D001483:Base Sequence; D001921:Brain / Q000473:pathology; D002874:Chromosome Mapping; D003241:Consanguinity; D004252:DNA Mutational Analysis; D005190:Family; D005260:Female; D016368:Frameshift Mutation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics*; D018895:Microsatellite Repeats; D010375:Pedigree; D017354:Point Mutation; D020641:Polymorphism, Single Nucleotide; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012529:Saudi Arabia; D017384:Sequence Deletion; D055815:Young Adult
D000071183:Autophagy-Related Proteins; D047908:Intracellular Signaling Peptides and Proteins; C552537:RUBCN protein, human