FTLD-ALS of TDP-43 type and SCA2 in a family with a full ataxin-2 polyglutamine expansion.
Polyglutamine expansions in the ataxin-2 gene (ATXN2) cause autosomal dominant spinocerebellar ataxia type 2 (SCA2), but have recently also been associated with amyotrophic lateral sclerosis (ALS). We present clinical and pathological features of a family in which a pathological ATXN2 expansion led to frontotemporal lobar degeneration with ALS (FTLD-ALS) in the index case, but typical SCA2 in a son, and compare the neuropathology with a case of typical SCA2. The index case shares the molecular signature of SCA2 with prominent polyglutamine and p62-positive intranuclear neuronal inclusions mainly in the pontine nuclei, while harbouring more pronounced neocortical and spinal TDP-43 pathology. We conclude that ATXN2 mutations can cause not only ALS, but also a neuropathological overlap syndrome of SCA2 and FTLD presenting clinically as pure FTLD-ALS without ataxia. The cause of the phenotypic heterogeneity remains unexplained, but the presence of a CAA-interrupted CAG repeat in the FTLD case in this family suggests that one potential mechanism may be variation in repeat tract composition between members of the same family.
Department of Neuropathology, John Radcliffe Hospital, University of Oxford, Headley Way, Oxford, OX3 9DU, UK.
Dirk
D
Bäumer
Simon Z
SZ
East
Bing
B
Tseu
Adam
A
Zeman
David
D
Hilton
Kevin
K
Talbot
Olaf
O
Ansorge
D000369:Aged, 80 and over; D000690:Amyotrophic Lateral Sclerosis / Q000150:complications* / Q000235:genetics* / Q000473:pathology; D000067528:Ataxins; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005192:Family Health; D006801:Humans; D008297:Male; D009419:Nerve Tissue Proteins / Q000235:genetics*; D020754:Spinocerebellar Ataxias / Q000150:complications* / Q000235:genetics* / Q000473:pathology; D019680:Trinucleotide Repeat Expansion
D000067528:Ataxins; D004268:DNA-Binding Proteins; D009419:Nerve Tissue Proteins