Question: Which are the most commonly reported pathological states associated with the formation of DNA G-quadruplexes?

Context:
Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) were recently shown to be caused by expansion of a (GGGGCC)n/(GGCCCC)n repeat in the C9ORF72 gene
Myocardial fibrosis is a key pathological change in a variety of heart diseases contributing to the development of heart failure, arrhythmias, and sudden death. Recent studies have shown that relaxin prevents and reverses cardiac fibrosis. Endogenous expression of relaxin was elevated in the setting of heart disease; the extent of such up-regulation, however, is insufficient to exert compensatory actions, and the mechanism regulating relaxin expression is poorly defined. In the rat relaxin-1 (RLN1, Chr1) gene promoter region we found presence of repeated guanine (G)-rich sequences, which allowed formation and stabilization of G-quadruplexes with the addition of a G-quadruplex interactive ligand berberine.
Up-regulating relaxin expression by G-quadruplex interactive ligand to achieve antifibrotic action
Our findings document a novel therapeutic strategy for fibrosis through up-regulating expression of endogenous relaxin.
We identified a G-rich sequence within exon 3 of BACE1 involved in controlling splice site selection
β-Site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1) is the transmembrane aspartyl protease that catalyzes the first cleavage step in the proteolysis of the APP to the amyloid β-protein (Aβ), a process involved in the pathogenesis of Alzheimer disease
Anti-amyloidogenic processing of the amyloid precursor protein APP by α-secretase prevents formation of the amyloid-β peptide, which accumulates in senile plaques of Alzheimer disease patients. α-Secretase belongs to the family of a disintegrin and metalloproteases (ADAMs), and ADAM10 is the primary candidate for this anti-amyloidogenic activity
Using circular dichroism spectroscopy, we demonstrate that a G-rich region between nucleotides 66 and 94 of the ADAM10 5'-UTR forms a highly stable, intramolecular, parallel G-quadruplex secondary structure under physiological conditions
FANCJ helicase defective in Fanconia anemia and breast cancer unwinds G-quadruplex DNA to defend genomic stability.
Telomerase inhibition with a novel G-quadruplex-interactive agent, telomestatin: in vitro and in vivo studies in acute leukemia
Recently, we have demonstrated that treatment with a G-quadruplex-interactive agent, telomestatin reproducibly inhibited telomerase activity in the BCR-ABL-positive leukemic cell lines
A G-quadruplex-interactive agent, telomestatin (SOT-095), induces telomere shortening with apoptosis and enhances chemosensitivity in acute myeloid leukemia
We examined G-quadruplex interactive agent, telomestatin (SOT-095), for its ability to inhibit the proliferation of human leukemia cells, including freshly obtained leukemia cells.

Answer: There is a growing recognition for the profound role of G-quadruplexes in a wide spectrum of diseases, such as cancer, diabetes and cardiovascular disease. Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) were recently shown to be caused by expansion of a (GGGGCC)n/(GGCCCC)n repeat in the C9ORF72 gene.  Treatment with a G-quadruplex interactive ligand was shown to achieve antifibrotic action. G-quadruplex forming sequences have also been linked with ADAM10 a primary candidate for anti-amyloidogenic activity in Alzheimer's. A G-quadruplex-interactive agent, telomestatin (SOT-095), induces telomere shortening with apoptosis and enhances chemosensitivity in acute myeloid leukemia.
Exact answer: Amyotrophic lateral sclerosis (ALS)
frontotemporal dementia (FTD)
Alzheimer's disease
fibrosis
acute myeloid leukemia