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Apolipoprotein E alleles in sporadic inclusion-body myositis and hereditary inclusion-body myopathy.

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LETTERS
Apolipoprotein E Alleles in Sporadic
Inclusion-Body Myositis and Hereditary
Inclusion-Body Myopathy
Valerie Askanas, MD, PhD,* W. King Engel, MD,'
Massimiliano Mirabella, MD,* Karl H , Weisgraber, PhD,?
Ann M. Saunders, PhD,$ Allen D. Roses, MD,$
and Janis McFerrin, BS*
In the recent issue of Annals, Garlepp and co-workers [I]
reported increased frequency of apolipoprotein (apoE) 4 allele in sporadic inclusion-body myositis (s-IBM), based on
studies performed in 14 Australian white patients [I]. In
contrast, Harrington and associates [2]reported no increase
of apoE 4 allele frequency in 11 s-IBM patients from the
United Kingdom. ApoE is associated histopathologically
with neurofibrillary tangles of Alzheimer's disease (AD) [ 3 ] .
An increased frequency of the apoE 4 allele has been demonrestrated in both late-onset-familial and sporadic AD ([4],
viewed in reference 5). Because the muscle-fiber phenotype
of s-IBM and hereditary inclusion-body myopathy (h-IBM)
strikingly resembles that of AD brain, including abnormal
hyperaccumulations of apoE [6], P-amyloid protein [7],
phosphorylated T [S], and other proteins (reviewed in reference 9 ) , it is important to establish whether an increased
frequency of the apoE 4 allele is also associated with s- and/
or h-IBM.
We studied distribution of the apoE. alleles in 11 patients
with s-IBM and 12 with h-IBM. s-1BM patients included 1
Pakistani, 2 Chinese, 1 Latino, and 7 white patients. Among
h-IBM patients, 10 were Persian Jews and 1 was Pakistani.
All s- and h-IBM patients had their diagnosis confirmed by
our established diagnostic criteria IS]. The 35 disease-control
patients included those with amyotrophic lateral sclerosis,
progressive muscular arrophy, myasthenia gravis, polymyositis, various peripheral' neuropathies, spastic paraparesis plus
epilepsy, and morphologically nonspecific rnyopathies. D N A
was extracted and apoE alleles studied :according to described
methods [ 4 ] ,without knowiedge of the patients' diagnoses.
There was no increased frequency ofapoE 4 allele in either
s- or h-IBM (Table). Our studies demonstrate that among
our patients the frequency of the apoE 4 allele is not increased in either s- or h-IBM. Therefore, increased apoE 4
does not appear to be a risk factor for the IBMs.
The reason for the unusual similarity between pathology
of TBM muscle and AD brain is not known, but a cascade
of similar pathogenic steps occurring in the muscle fiber and
neuron, but provoked by different causes, is a possibility. A
tissue-specific intracellular aging change could be a necessary
requirement in both the IBMs and AD.
"USC Neuromziscular Center
Department of Neurology
University of Southern California School of Medicine
Good Samaritan Hospital
Los Angeles, C4 90017-1912
?Gladstone Institute of Cardiovascular Disease
Universiq o f California
San Francisco, CA 941 10
$Division of Neurology
Duke University Medical Center
Durham, NC 2771 0
References
1. Garlepp MJ, Tabarias H, van Bockxmeer FM, et ai. Apolipoprorein E &4in inclusion body myositis. Ann Neurol 1995;38:957-
959
2. Harrington CR, Anderson JR, Chan KK. Apolipoprotein E type
E4 allele frequency is not increased in patienrs wirh sporadic
inclusion-body myositis. Neurosci Lett I995;183:35-38
3. Namba Y, 'Tomonaga M, Kawasaki H, et al. Apolipoprotein E
immunoreaccivity in cerebral amyloid deposits and neurofibrillary tangles in Alzheimer's disease and kuru plaque amyloid in
Creutzfeld-Jakob disease. Brain Res 1991;541:163-166
4. Saunders AM, Strittmatter WJ, Schmcchel D, et al. Association
of apolipoprotein E allele ~4 with late-onset familial and sporadic Alzheimer's disease. Neurology 1993;43:1467-1 472
5. Roses AD. Perspective: on the metabolism of apolipoprotein E
and the Alzheimer diseases. Enp Neurol 1995;132:149-156
6. Askanas V, Mirabella M , Engel WK, et al. Apolipoprotein E
immunoreactive deposits in inclusion-body muscle diseases.
Lancet 1994;343:364-365
7. Askanas V, Engel MK, Alvarez RB. Light- and electronniicroscopic localization of P-amyloid protein in muscle biopsies of
patients with inclusion-body myositis. Am J Pathol 1992;141:
31-36
8. Askanas V, Engel WK, Bilak M, et al. Twisted tubulofilaments
of inclusion-body myositis muscle resemble paired helical filaments of Alzheimer brain and contain hyperphosphorylated tau.
Am J Pathol 1994;144:177-187
9. Askanas V, Engel MK. New advances in the understanding of
sporadic inclusion-body myositis and hereditary inclusion-body
myopathics. Curr Opin Rheumatol 1995;7:486-496
Reply
Michael J. Garlepp, PhD, and Frank L. Mastaglia, M D
Apolipoprotein E Alleles in Sporadic Inclusion-Body Myositis
and Hereditary Inclusion-Body Myopathy
Patients
Number
of Alleles
S-IBM
h-IBM
Disease control
22
24
70
Median
Age
(yr)
67
38
65
ApoE Allele
Frequencies
E2
E3
E4
0.09
0.08
0.10
0.86
0.87
0.05
0.05
0.11
0.74
ApoE = apolipoprotein E; s-IBM = sporadic inclusion-body myositis; h-IBM = hereditary inclusion-body myopathy.
264
W e note with interest the results presented by Askanas and
colleagues in which they report that the incidence of the
apolipoprotein E (apoE) ~4 allele in their patients with inclusion-body myositis (IBM) was not increased compared with
controls. This study and the previous two published studies
[ 1, 21, which have addressed this issue, have suffered from
the obvious limitation that relatively few cases were available
for analysis. This may be one reason for the discrepancy in
reported results. However, other explanations are possible.
IBM may well be heterogeneous in its etiology, and the
final manifestation as inclusion-body myopathy, with or
without associated inflammation, may be reached via more
Copyright 0 1996 by the American Neurological Association
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myopathy, allele, inclusion, apolipoprotein, myositis, hereditary, body, sporadic
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