RT Journal Article
SR Electronic
T1 <em>UNC80</em> mutation causes a syndrome of hypotonia, severe intellectual disability, dyskinesia and dysmorphism, similar to that caused by mutations in its interacting cation channel <em>NALCN</em>
JF Journal of Medical Genetics
JO J Med Genet
FD BMJ Publishing Group Ltd
SP 397
OP 402
DO 10.1136/jmedgenet-2015-103352
VO 53
IS 6
A1 Yonatan Perez
A1 Rotem Kadir
A1 Michael Volodarsky
A1 Iris Noyman
A1 Hagit Flusser
A1 Zamir Shorer
A1 Libe Gradstein
A1 Ramon Y Birnbaum
A1 Ohad S Birk
YR 2016
UL http://jmg.bmj.com/content/53/6/397.abstract
AB Background A syndrome of profound hypotonia, intellectual disability, intrauterine growth retardation with subsequent failure to thrive, dyskinesia and epilepsy was diagnosed in Bedouin Israeli families. Mild dysmorphism was evident: plagiocephaly, broad forehead with prominent nose, smooth philtrum and congenital esotropia. We set out to decipher the molecular basis of this syndrome.Methods Genome-wide linkage analysis and fine mapping were done. Whole exome sequencing data were filtered for candidate variants within locus. Validation and segregation of the mutation was assayed via Sanger sequencing. UNC80 expression pattern was analysed through reverse transcription PCR.Results Homozygosity mapping followed by fine mapping identified a 7.5 Mb disease-associated locus (logarithm of odds score 3.5) on chromosome 2. Whole exome and Sanger sequencing identified a single homozygous nonsense mutation within this locus, segregating within the families as expected for recessive heredity and not found in a homozygous state in 150 Bedouin controls: c.151C&gt;T, p.(R51*) in UNC80.Conclusions The syndrome described is caused by a mutation in UNC80, truncating most of the 3258 amino acids highly conserved encoded protein, that has no known motifs. UNC80 bridges between UNC79 and the cation channel NALCN, enabling NALCN's role in basal Na+ leak conductance in neurons, essential for neuronal function. The phenotype caused by the UNC80 mutation resembles that previously described for homozygous NALCN mutations.