Best Post of February 2016: Cerebellar dentate neuron undergoing grumose degeneration in a case of progressive supranuclear palsy

The next in our "Best of the Month" series comes from February 1, 2016 and is composed entirely of a photomicrograph of a lone neuron suffering from PSP:

Bodian stain

Genetics of PSP further elucidated

Actor Dudley Moore died in 2002 with PSP

About 20,000 people in the United States are currently diagnosed with Progressive Supranuclear Palsy (PSP). A variant in the MAPT gene, has been repeatedly linked to the disease. Researchers led by Gunter Höglinger of Philipps-Universitat in Germany studied more than 2,000 individuals of European descent diagnosed with PSP, comparing their DNA to that of nearly 7,000 healthy European individuals. The results were published last month in the journal Nature Genetics. The study reported several single nucleotide polymorphisms (SNPs) associated with the disease. One of the SNPs reported by Höglinger’s team is located in MAPT and is closely linked to the already well-established variant for PSP risk. In this study, each copy of the G version of rs8070723 in MAPT was associated with about 5.5 times lower odds of the disease. (Source: spittoon.23andme.com)

Grumose degeneration in the cerebellar dentate nucleus

It’s hard to find a picture of grumose degeneration in a textbook or online. I did, however, find one in an article by Yamanouchi et al. entitled “An Autopsy case of ornithine transcarbamylase deficiency” [Brain & Development 24 (2002) 91-94]. Grumose degeneration appears as eosinophilic granular material around dentate neurons. Neuropathologists usually think of grumose degeneration of the cerebellar dentate as an autopsy finding in progressive supranuclear palsy (PSP). But the authors of this article describe the same finding in a case of ornithine transcarbamylase deficiency, the most common heritable urea cycle disorder. They point out that although grumose degeneration was first described in a patient with PSP, it has also been reported in certain other neurodegenerative disorders, such as dentatorubropallidoluysian atrophy, Ramsay-Hunt syndrome, and juvenile Alzheimer disease with myoclonus. Ultrastructural studies have revealed that this eosinophilic material corresponds to degenerate Purkinje cell axon terminals. By the way, the word ‘grumose’, which can also be spelled ‘grumous’, means granular and refers to something that resembles grume, which is (according to Webster’s online dictionary) a thick, viscid fluid or clot-like material.