Acta Neuropathol (1998) 95 : 333–337

© Springer-Verlag 1998

R E G U L A R PA P E R

Hitoshi Takahashi · Takeshi Ikeuchi · Yoshiaki Honma ·
Shintaro Hayashi · Shoji Tsuji

Autosomal dominant cerebellar ataxia (SCA6):
clinical, genetic and neuropathological study in a family

Received: 27 May 1997 / Revised, accepted: 27 October 1997

Abstract We describe a family with dominantly inherited ataxia of late adult onset. Expansion of a CAG repeat
in the gene encoding the α1A voltage-dependent calcium
channel was identified at autopsy in one patient, a 65-yearold woman with a disease duration of 11 years. In this patient, pathological changes were confined to the cerebellar
cortex and inferior olivary complex. The cerebellar cortex
showed severe loss of Purkinje cells with proliferation of
Bergmann’s glia, being more pronounced in the superior
parts of the vermis and hemispheres. In the inferior olivary complex, a reduced neuronal cell population, which
could be interpreted as a change secondary to the cerebellar cortical lesion, was evident. We conclude that the pathological phenotype of this newly classified autosomal dominant cerebellar ataxia, SCA6, is cerebello-olivary atrophy, or more strictly cerebellar cortical atrophy.

clarity [10, 20]. Recently, Sanpei et al. [22] found that
novel expansion of a CAG repeat is the causative mutation responsible for spinocerebellar ataxia type 2 (SCA2).
Shortly after this, Zhuchenko et al. [26] reported that expansion of a CAG repeat in the gene encoding the α1A
voltage-dependent Ca2+ channel was the cause of late-onset dominantly inherited ataxia, and this became a new
addition to the above classification as an autosomal dominant spinocerebellar ataxia, SCA6. At present, however,
the neuropathological features of this new genetically defined disease have been described for only one family
[23]. Here we report another family with SCA6, of which
one affected member was examined at autopsy.

Key words Ataxia · Autosomal dominance ·
Cerebello-olivary atrophy · CAG repeat expansion ·
SCA6

Clinical study

Introduction
The rapid progress made in the genetic investigation of
dominantly inherited spinocerebellar ataxias (SCAs) has
made it possible to provide a genotype classification, in
which several disorders have already been listed with

H. Takahashi (Y) · S. Hayashi
Department of Pathology, Brain Research Institute,
Niigata University, 1 Asahimaschi, Niigata 951-8585, Japan
Tel.: 81-25-223-6161, ext. 5151; Fax: 81-25-223-7503;
e-mail: hitoshi@bri.niigata-u.ac.jp
T. Ikeuchi · S. Tsuji
Department of Neurology, Brain Research Institute,
Niigata University, Niigata, Japan
Y. Honma
Department of Neurology, Sado General Hospital,
Sado, Niigata, Japan

Materials and methods

In this family, clinical examinations of two affected members, patients 1 (IV-1) and 2 (IV-6), were performed. An autopsy was later
performed on patient 1. From accounts given by the family members, including patient 1, three other individuals, patients 3 (III-2),
4 (II-1) and 5 (I-1), were said to have been affected by an almost
identical disorder. Three siblings of patient 1 were said to have
died in infancy, but the causes of death were unknown.
Genetic analysis
High-molecular-weight genomic DNA was extracted from the
frozen brain tissue of patient 1 [21]. The CAG repeat size in the
α1A voltage-dependent Ca2+ channel gene was determined by the
polymerase chain reaction (PCR) using oligonucleotide primers
(CACNL1AF: 5′-TCAACATCTGGTACCAGCACTCC-3′, CACNL1AR: 5′-TACCTCCGAGGGCCGCTGGTG-3′) in 25 µl of solution containing 200 µM each of dATP, dGTP, and TTP, 20 µM
dCTP, 1 µM of each primer, 1.5 mM MgCl2, 50 mM KCl, 10 mM
TRIS-HCl, pH 8, 200 ng of genomic DNA, 0.15 µl of [32P]dCTP
(111 TBq/mmol), and 1 unit of Taq polymerase (Takara, Japan).
The thermal controller for amplification was programmed for an
initial 2-min denaturation at 96° C, followed by 30 cycles of 1 min
at 96° C, 1 min at 62° C and 1 min at 72° C, and a final 10-min extension at 72° C. Aliquots of the PCR products were run through
6% denaturing polyacrylamide gels in 1 × TRIS-borate (TBE)
buffer, and autoradiographed on Fuji RX film at –70° C using an
intensifying screen.

334
Neuropathological methods
Histological examination of patient 1 was performed on formalinfixed, paraffin-embedded sections using several stains, including
hematoxylin and eosin (H & E), Klüver-Barrera (Luxol fast blue/
cresyl violet), Holzer, Bodian’s method and methenamine silver.
Selected sections were also stained by the modified Gallyas-Braak
method [5, 24], or immunostained with a mouse monoclonal
antibody against tau-2 (Dakopatts, Glostrup, Denmark; diluted
1:2000), using the avidin-biotin-peroxidase method.

Results
Case reports
Patient 1 (proband, IV-1, Fig. 1)
The patient had been healthy until the age of 54 years,
when slurred speech and unsteady gait appeared. On neurological examination, instability when standing on one

Fig. 1 Family pedigree

leg was observed. The Achilles’ tendon reflex was absent
on the left side, whereas the other deep tendon reflexes
were exaggerated. Thereafter, gait ataxia and dysarthria
progressed slowly, but steadily. At the age of 56, ataxia
was also apparent in the upper limbs. At the age of 59, the
patient became unable to walk without assistance. At the
age of 65 years, she became bedridden, and exhibited gazeevoked nystagmus and intention tremor, and died about 11
years after onset of the disease. The direct cause of death
was colon cancer, which was found and removed surgically 7 months before death, but metastasis to the liver
was already present at that time. During the course of her
illness, there was no evidence of dementia, and no sensory
or autonomic disorder, or muscle weakness developed.
Results of laboratory tests, including cerebrospinal fluid
and blood, were unremarkable.
Patient 2 (IV-6)
This female patient had been healthy until the age of 48
years, when slurred speech and unsteadiness of gait appeared. These symptoms progressed slowly. At the age of
57, gaze-evoked nystagmus became apparent. At age 59,
the patient became unable to walk without assistance. At
age 63, intension tremor and ataxia in the upper limbs became apparent. At the time of writing, she is 67 years old
and virtually chair bound. Computed tomography revealed
atrophy of the cerebellum (Fig. 2). All deep tendon reflexes were exaggerated. No pathological reflexes were
elicited. There was no evidence of dementia, and no sensory or autonomic disorder, or muscle weakness has developed so far.
Patients 3 (III-2) and 4 (II-1)
Patient 3 had been healthy until the age of 50 years, when
speech and gait difficulties appeared. At the age of 60, he
Fig. 3 The expanded allele
with 22 CAG repeats was
shown in patient 1 at autopsy

Fig. 2 A computed tomography scan of patient 2 showing severe
cerebellar cortical atrophy and dilatation of the fourth ventricle

335

Fig. 4 a Mid-sagittal section through the cerebellar vermis showing folial atrophy, being more marked in the superior part. b No
pathological changes are evident in the pons, including the middle
cerebellar peduncle (left). Neurons in the pontine nuclei are well
preserved (right). c The superior part of the vermis showing almost
complete loss of Purkinje cells. d The rostral part of the principal
inferior olivary nucleus showing obvious neuronal loss and gliosis.
b Klüver-Barrera, left ×1.2, right ×200; c, d H&E, c ×100, d ×125

committed suicide because of the distress caused by the
disease. Patient 4 died at the age of 80 years.
Genetic analysis
The numbers of CAG repeats in patient 1 were 22 and 13
(Fig. 3).
Neuropathological findings
Autopsy of patient 1 was performed 11 h after death. The
investigation was limited to the brain and the spinal cord,
together with the anterior and posterior nerve roots, the
cervical dorsal root ganglion, and the tibial nerve in the
popliteal region.
The brain weighed 1310 g before fixation. The cerebellum appeared very small and atrophic in comparison
with the cerebrum and brain stem, which were fairly well
proportioned in relation to each other. The spinal cord was
unremarkable. In sections, the cerebellum showed atrophy

of the folia with open fissures, being more marked in the
superior parts of the vermis and hemispheres (Fig. 4a).
The cerebrum and brain stem were of normal appearance.
Histologically, the significant changes were confined to
the cerebellar cortex and inferior olivary complex. No apparent changes were found elsewhere in the CNS, including the spinal cord, particularly the pons (Fig. 4b) and
basal ganglia, which were of normal histological appearance. The lumbar anterior and posterior nerve roots, cervical dorsal root ganglion and tibial nerve were also intact.
The cerebellar cortex revealed severe loss of Purkinje
cells with proliferation of Bergmann’s glia (Fig. 4c). Severe loss of granule cells was also noted. The molecular
layer was reduced in width with an increase of astrocytic
nuclei. These changes were more pronounced in the superior parts of the vermis and hemispheres. The folial white
matter showed myelin pallor and fibrillary gliosis, the degree of which appeared to correspond to that of the cortical degeneration. The deep white matter and cerebellar
peduncles were of normal histological appearance. The
dentate nucleus was well preserved with abundant neurons, although gliosis was evident there, and also in the
surrounding white matter (amiculum).
In the inferior olivary complex, which was examined at
three different levels, mild to moderate loss of neurons
with gliosis was observed, being more pronounced in the
rostral part of the principal inferior olivary nucleus (Fig.
4d) as well as in the caudal part of the medial accessory
olivary nucleus. In the principal inferior olivary nucleus

336

itself, such changes were more marked in the dorsal band
than in the ventral band.
No argyrophilic or tau-positive structures could be found
in the cerebellum, pons or medulla oblongata, as far as
could be examined. In the cerebrum, only a small number
of neurofibrillary tangles were observed in the hippocampus and parahippocampal gyrus.

Discussion
In this family, it appears almost certain that through five
successive generations, at least five patients developed
very similar late-onset cerebellar ataxia and that the disease was inherited as an autosomal dominant trait. In the
two patients examined, the cardinal symptoms were slowly,
but steadily progressive gait and limb ataxia, and dysarthria. Nystagmus was also noted, but other oculomotor
findings were negative. None of the patients had dementia, sensory or autonomic disorder, or muscle weakness.
The clinical features appeared to be those of “pure” autosomal dominant cerebellar ataxia of late onset (ADCA III)
[10–12].
Our genetic study revealed that patient 1 had a disease
resulting from the SCA6 mutation with 22 CAG repeats,
i.e., the expansion of a CAG repeat in the gene encoding
the α1A voltage-dependent Ca2+ channel. Zhuchenko et al.
[26] reported that the patients they examined had alleles
with larger repeat numbers (21–27) compared to the number of repeats (4–16) in control subjects. It is noteworthy
that other neurological diseases, including familial hemiplegic migraine and episodic ataxia type-2, have been reported to be caused by different mutations in the same gene
encoding the α1A voltage-dependent Ca2+ channel [16].
In our patient 1, the neuropathological changes were
confined to the cerebellar cortex and inferior olivary complex. The neuropathology of SCA6 has so far been described for only one family; Zhuchenko et al. [26] simultaneously disclosed that one family with dominantly inherited ataxia with late onset, which had been described
originally by Subramony et al. [23], was an example of
SCA6, showing mutations with 22 CAG repeats in one
living affected member and one autopsied one. Subramony et al. [23] performed neuropathological examinations of two affected members, and reported that the features, which were concordant between the two, were consistent with cerebello-olivary atrophy [6]; there was severe loss of Purkinje cells with less severe loss of granule
cells and thinning of the molecular layer. Mild to moderate loss of neurons in the inferior olives and dentate nucleus was also evident. The spinal cord was examined in
one affected member, showing no pathological changes.
Several families with dominantly inherited ataxias and
cerebello-olivary atrophies have been described [1–4, 8,
9, 13, 19, 25]. It is not certain whether these represent a
genetically homogeneous entity, and they may represent
spinocerebellar ataxia type 5 (SCA5), whose clinical phenotype is very similar to that of SCA6 [10, 18, 20]. However, reviewing the reported pathological findings appears

to be of importance for a better understanding of SCA6
neuropathology. Akelatis [1] reported two patients from
one family on whom autopsies were performed, who had
died within 2 years after onset. Concordance of neuropathological findings was documented in the two; the
grossly normal cerebella showed loss of Purkinje cells,
being more marked in the superior vermis, but the molecular and granular layers as well as the white matter were
of normal histological appearance, suggesting that the initial and primary change occurs in the cerebellar Purkinje
cells, starting from the superior vermis. With regard to
loss of the granule cells in the cases of SCA6 examined by
Subramony et al. [23] and our group, the possibility that it
is a change secondary to loss of Purkinje cells can be considered.
In our patient 1, the distribution of neuronal loss in the
inferior olivary complex appeared to correspond anatomically to that of Purkinje cell loss in the cerebellar cortex.
Similar observations were made by previous investigators
[1, 2, 8, 9, 13, 19, 25]. This type of neuronal loss in the inferior olivary complex has been interpreted as a change
representing retrograde transsynaptic degeneration secondary to the cerebellar cortical lesion [14]. Indeed, the
extent of the inferior olivary complex degeneration never
surpasses that of cerebellar cortical degeneration in cerebello-olivary atrophy.
The dentate nucleus may show neuronal loss [6]. Hoffman et al. [13] stated that the dentate nucleus was involved, with loss of approximately 10% of its neurons in
the case they studied. However, in several other cases,
neuronal loss was not evident in this nucleus [1, 8, 9, 25].
Richter [19] emphasized that there were local differences
in the severity of neuronal degeneration in the dentate nucleus, and that there was obvious fibrillary gliosis in the
dentate nucleus itself as well as in the surrounding white
matter. The cases of SCA6 described by Subramony et al.
[23] were reported to show mild to moderate neuronal
loss in the dentate nucleus. In our patient 1, neurons in the
dentate nucleus were well preserved, although myelin pallor and gliosis were evident in the background and surrounding white matter (amiculum). It is considered that in
cerebello-olivary atrophy, the dentate nucleus is usually
unremarkable, and even if neuronal loss is evident, it is a
change representing anterograde transsynaptic degeneration secondary to loss of the cerebellar Purkinje cells [19],
and presumably, also of the inferior olivary complex neurons.
It is interesting to note that Gilman et al. [7] have recently reported a family with the SCA1 mutation, of which
at autopsy one patient showed argyrophilic, tau-positive
glial cytoplasmic inclusions in several regions in the CNS,
including the cerebellum. These glial cytoplasmic inclusions were very similar, if not identical, to those first described in multiple system atrophy [15, 17]. In our patient
1, however, no such inclusions could be found. Subramony et al. [23] did not mention this feature.
In conclusion, the three autopsy cases from two different families with genetically identified SCA6 described so
far strongly suggest that the pathological phenotype of

337

this disease is cerebello-olivary atrophy [6]. Taken together with the clinicopathologically similar previous
cases, we believe that in a strict sense, the disease is a
form of cerebellar cortical atrophy [19], and that glial cytoplasmic inclusions could not be a feature.
Acknowledgements We wish to express our appreciation to Mr.
S. Egawa, Mr. T. Hasegawa, Ms. C. Tanda, and Ms. Y. Ohta for
their technical assistance, and to Ms. M. Machida and Ms. K. Abe
for their help in preparing the manuscript.

References
1. Akelaitis AJ (1938) Hereditary form of primary parenchimatous atrophy of the cerebellar cortex associated with mental deterioration. Am J Psychiatry 94: 1115–1140
2. Bielschowsky M, Bouman L, Sillevis Smitt WG (1934) Über
eine ungewöhnliche Form von cerebellarer Heredoataxie. J
Psychiatr Neurol 51: 1–15
3. Bogaert LV (1947) Sur une atrophie cérébelleuse tradive du
type Marie-Foix-Alajouanine héréditaire et familiale avec une
atrophie pallidale partielle cliniquement muette. J Belge Neurol
Psychiatry 47: 268–286
4. Bonni A, Carpio-O’Donovan RD, Robitaille Y, Andermann E,
Andermann F, Arnold DA (1993) Magnetic resonance imaging
in the diagnosis of dominantly inherited cerebello-olivary atrophy: a clinicopathologic study. Can Assoc Radiol J 44: 194–
198
5. Braak H, Braak E, Ohm T, Bohl J (1988) Silver impregnation
of Alzheimer’s neurofibrillary changes counterstained for basophilic material and lipofuscin pigment. Stain Technol 63:
197–200
6. Eadie MJ (1975) Cerebello-olivary atrophy (Holmes type).
Handb Clin Neurol 21: 403–414
7. Gilman S, Sima AAF, Junck L, Kluin KJ, Koeppe RA, Lohman
MA, Little R (1996) Spinocerebellar ataxia type I with multiple
system degeneration and glial cytoplasmic inclusions. Ann
Neurol 39: 241–255
8. Hall B, Noad KB, Latham O (1941) Familial cortical cerebellar
atrophy. Brain 64: 178–194
9. Hall B, Noad KB, Latham O (1945) Familial cortical cerebellar
atrophy: a contribution to the study of heredo-familial cerebellar disease in Australia. Med J Aust 1: 101–108
10. Hammans SR (1996) The inherited ataxias and the new genetics. J Neurol Neurosurg Psychiatry 61: 327–332
11. Harding AE (1982) The clinical features and classification of
the late onset autosomal dominant cerebellar ataxias. A study
of 11 families, including descendants of ‘the Drew family of
Walworth’. Brain 105: 1–28

12. Harding AE (1993) Clinical features and classification of inherited ataxias. Adv Neurol 61: 1–14
13. Hoffman PM, Stuart WH, Earle KM, Brody JA (1971) Hereditary late-onset cerebellar degeneration. Neurology 21: 771–777
14. Holmes G, Stewart TG (1908) On the connection of the inferior
olives with the cerebellum in man. Brain 31: 125–135
15. Nakazato Y, Yamazaki H, Hirato J, Ishida Y, Yamaguchi H
(1990) Oligodendroglial microtubular tangles in olivopontocerebellar atrophy. J Neuropathol Exp Neurol 49: 521–530
16. Ophoff RA, Terwindt GM, Vergouwe MN, Eijk R van, Oefner
PJ, Hoffman SMG, Lamerdin JE, Mohrenweiser HW, Bulman
DE, Ferrari M, Haan J, Lindhout D, Ommen G-JB van, Hofker
MH, Ferrari MD, Frants RR (1996) Familial hemiplegic migraine and episodic ataxia type-2 are caused by mutations in
the Ca2+ channel gene CACNL1A4. Cell 87: 543–552
17. Papp MI, Kahn JE, Lantos P (1989) Glial cytoplasmic inclusions in the CNS of patients with multiple system atrophy (striatonigral degeneration, olivopontocerebellar atrophy and ShyDrager sysdrome). J Neurol Sci 94: 79–100
18. Ranum LPW, Schut LJ, Lundgren JK, Orr HT, Livingston DM
(1994) Spinocerebellar ataxia type 5 in a family descended
from the grandparents of President Lincoln maps to chromosome 11. Nat Genet 8: 280–284
19. Richter RB (1950) Late cortical cerebellar atrophy. A form of
hereditary ataxia. Am J Hum Genet 2: 1–29
20. Rosenberg RN (1995) Autosomal dominant cerebellar phenotypes: the genotype has settled the disease. Neurology 45: 1–5
21. Sambrook J, Fritsch EF, Maniatis T (1989) Molecular cloning:
a laboratory manual, 2nd edn. Cold Spring Harbor Laboratory
Press, Cold Spring Harbor
22. Sanpei K, Takano H, Igarashi S, et al (1996) Identification of
the spinocerebellar ataxia type 2 gene using a direct identification of repeat expansion and cloning technique, DIRECT. Nat
Genet 14: 277–284
23. Subramony SH, Fratkin JD, Manyam BN, Currier RD (1996)
Dominantly inherited cerebello-olivary atrophy is not due to a
mutation at the spinocerebellar ataxia-I, Machado-Joseph disease, or dentato-rubro-pallido-luysian atrophy locus. Mov Disord 11: 174–180
24. Wakabayashi K, Takahashi H (1996) Similarities and differences among progresive supranuclear palsy, corticobasal degeneration and Pick’s disease. Neuropathology 16: 262–268
25. Weber FP, Greenfield JG (1942) Cerebello-olivay degeneration: an example of heredo-familial incidence. Brain 65: 220–
231
26. Zhuchenko O, Bailey J, Bonnen P, Ashizawa T, Stockton DW,
Amos C, Dobyns WB, Subramony SH, Zoghbi HY, Lee CC
(1997) Autosomal dominant cerebellar ataxia (SCA6) associated with small polyglutamine expansion in the α1A-voltagedependent calcium channel. Nat Genet 15: 62–69