Intermediate length C9orf72 expansion in an ALS patient without classical C9orf72 neuropathology

There was no family history of neuromuscular disease. Examination revealed weakness particularly in the lower limbs, hyperrefl exia, wasting and fas-ciculation. There was no sensory or cognitive impair-ment. A diagnosis of ALS was made following full neurological investigation. She died from respiratory failure 31 months after symptom onset. Pathological material was obtained from the Sheffi eld Brain Tissue Bank. Ethics committee approval and written consent was obtained. Genomic DNA was extracted from cerebellar material and a C9orf72 expansion of 16 GGGGCC repeats was identifi ed by PCR analysis (Figure 1A) and Southern hybridization (8) (Figure 1B). Single nucleotide polymorphisms (SNPs) at rs3849942 and rs2814707 are highly associated with the 9p21 risk allele (1). Genotyping showed that our patient was heterozygous for the minor, or risk, allele at both positions. This is highly suggestive that her intermediate length expan-sion had occurred on the background of the 9p21 risk haplotype. Taqman allelic discrimination assay on an ABI 7900HT Real-Time PCR system was used for genotyping SNPs. Pre-designed primers and probes were purchased from Applied Biosystems (Foster City, USA). Histology revealed loss of lower motor neurons in the medulla and spinal cord with Bunina bodies in residual neurons. The motor cortex had detectable superfi cial cortical vacuolation. Immunohistochemis-try revealed p62 and TDP-43-positive neuronal and glial cytoplasmic inclusions in motor cortex, brain-stem and spinal cord. C9orf72 disease is associated with an abundance of ‘ star-shaped ’ ubiquitylated, TDP-43 negative inclusions in extramotor areas (6);