Diagnostic overview of blood-based dysferlin protein assay for dysferlinopathies.
BACKGROUND
Dysferlin deficiency causes dysferlinopathies. Among peripheral blood mononuclear cells (PBMCs), the dysferlin protein is expressed specifically in CD14(+) monocytes.


METHODS
We quantified dysferlin protein levels in PBMC lysates of 77 individuals suspected clinically of having a dysferlinopathy to screen for true positives. Subsequent molecular confirmation was done by Sanger sequencing and comparative genomic hybridization arrays to establish diagnosis.


RESULTS
Of the 44 individuals who had significantly reduced dysferlin levels (≤10%), 41 underwent molecular testing. We identified at least 1 mutation in 85% (35 of 41), and 2 mutations, establishing a dysferlinopathy diagnosis, in 61% (25 of 41) of these individuals. Among those with dysferlin protein levels of >10% (33 of 77), only 1 individual (of 14 who underwent molecular testing) had a detectable mutation.


CONCLUSIONS
Our results suggest that dysferlin protein levels of ≤10% in PBMCs, are highly indicative of primary dysferlinopathies. However, this assay may not distinguish carriers from those with secondary dysferlin reduction.
Department of Human Genetics, Emory University School of Medicine, 615 Michael Street, Atlanta, Georgia, 30322, USA.
Arunkanth
A
Ankala
Babi R
BR
Nallamilli
Laura E
LE
Rufibach
Esther
E
Hwang
Madhuri R
MR
Hegde
D000918:Antibody Specificity; D001345:Autoradiography; D015153:Blotting, Western; D000073939:Dysferlin; D004591:Electrophoresis, Polyacrylamide Gel; D005838:Genotype; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000235:genetics; D006801:Humans; D008565:Membrane Proteins / Q000097:blood* / Q000172:deficiency / Q000235:genetics*; D009000:Monocytes / Q000502:physiology; D009124:Muscle Proteins / Q000097:blood* / Q000172:deficiency / Q000235:genetics*; D049288:Muscular Dystrophies, Limb-Girdle / Q000097:blood* / Q000175:diagnosis* / Q000235:genetics; D015203:Reproducibility of Results
C114839:DYSF protein, human; D000073939:Dysferlin; D008565:Membrane Proteins; D009124:Muscle Proteins; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases
CD14+ monocytes; LGMD2B; Miyoshi myopathy; clinical diagnosis; dysferlin; immunoblotting