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Bioinformatics of the Brain

impact on the economies of countries. There are a multitude of studies in-

volving microarray techniques and many more are to be added till a cure for

this complex mind-boggling brain disease is established. In a comprehensive

study done by Takei and coworkers, a tissue microarray technique was used

to identify diffuse pathological processes in late stages of AD, dementia, and

amyotrophic lateral sclerosis (ALS) [47]. In another study Blauwendraat and

coworkers identified a diverse spectrum of mutation carriers observed novel

genotype-phenotype correlations in AD and Parkinson’s Disease (PD) [48].

Given how challenging it is to obtain a premortem brain tissue sample, it

is clear from the research that considerable effort has been made to identify

blood biomarkers for particular brain diseases and disorders in addition to

tissue biomarkers. Collection of blood samples is minimally intrusive, simple

to use, and economical. Such studies may involve the use of peripheral blood

mononuclear cells (PBMC), whole blood cells, lymphocytes, serum T-cells,

or red blood cells. For instance, Sakharkar et al. did a comparison of brain

and peripheral blood cell gene expression profiles of PD patients to assess

early indicators of the disease [49]. Their analysis results determined that the

identified genes do not represent a common biological pathway due to the

heterogenic structure of the disease. In another study, Miki and colleagues

performed whole transcriptome assay using PBMC from PD patients [50].

According to their findings, PD exhibits considerably elevated upstream au-

tophagy protein levels as well as negative feedback on the mRNA expression

of these proteins.

Neurons in the brain gradually degenerate due to Huntington’s disease

(HD), an uncommon hereditary condition. Zhou and colleagues analyzed post-

mortem prefrontal cortical tissue using microarrays from patients with HD

[51]. Their research revealed that reduced brain derived neurotrophic factor

expression is involved in HD pathogenesis and may be regulated by cAMP,

MAPK, and Ras signaling pathways. Revealing HD mechanism can be chal-

lenging due to the intricacy of the affected regions of the brain and cell types.

Thus, it is most likely to come across studies in animal models of this disease.

For instance, in a mouse cell line model of HD, Marfil-Marin, and colleagues

used microarray technology to discover the circRNAs (circular RNA’s) with

differential expression and the biochemical pathways regulated through these

circRNAs [52]. In a study that is first of its kind they discovered 23 circR-

NAs with variable expression, and they found that several pathways, like the

dopaminergic synapse, MAPK, and long-term depression were notably en-

riched.

There is a significant genetic predisposing factor for amyotrophic lateral

sclerosis (ALS), a fatal neurodegenerative illness which mostly impacts the

motor neuron system of humans. A whole blood transcriptome microarray

analysis of ALS carried out by Van Rheenen and coworkers discovered 2,943

transcripts that were differently expressed, mostly associated with RNA bind-

ing and intracellular trafficking [53]. Swindell and coworkers analyzed mi-

croarray data of blood samples derived from ALS patients and their healthy