A new diagnostic test for VLCAD deficiency using immunohistochemistry.
BACKGROUND
Muscle pathology is often unhelpful in elucidating the specific underlying abnormality in patients with metabolic myopathy with rhabdomyolysis, including very-long chain acyl-CoA dehydrogenase (VLCAD) deficiency. Biochemical analyses require large amounts of biopsy samples for each enzyme assay.


OBJECTIVE
To develop a more efficient diagnostic method for VLCAD deficiency.


METHODS
The authors performed immunohistochemical analysis using an antibody to VLCAD on muscles from 344 patients (226 men and 118 women) without a specific diagnosis who had at least one of the following symptoms: myoglobinuria, high CK level, muscle pain, muscle stiffness, sudden infant death syndrome, and Reye-like syndrome.


RESULTS
Immunoreactivity to VLCAD was absent or markedly reduced in 13 patients. Biochemical analyses confirmed that all these patients had low enzymatic activity and reduced amount of protein. They all had the myopathic phenotype. The authors identified homozygous or compound heterozygous mutations in all of them. All recombinant proteins had reduced enzymatic activity except for 128G>A (G43D) and 796C>G (P266A) mutants, indicating that they are neutral polymorphisms.


CONCLUSIONS
The new screening method for the detection of VLCAD deficiency using an immunohistochemical technique identified 13 new Japanese patients with VLCAD deficiency.
Ohashi
Y
Y
Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan.
Hasegawa
Y
Y
Murayama
K
K
Ogawa
M
M
Hasegawa
T
T
Kawai
M
M
Sakata
N
N
Yoshida
K
K
Yarita
H
H
Imai
K
K
Kumagai
I
I
Murakami
K
K
Hasegawa
H
H
Noguchi
S
S
Nonaka
I
I
Yamaguchi
S
S
Nishino
I
I
D044942:Acyl-CoA Dehydrogenase, Long-Chain / Q000172:deficiency* / Q000235:genetics; D000293:Adolescent; D000328:Adult; D001706:Biopsy; D002648:Child; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D005260:Female; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D008297:Male; D008661:Metabolism, Inborn Errors / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology*
D044942:Acyl-CoA Dehydrogenase, Long-Chain