Exploring the overlap between alopecia areata and major depressive disorder: Epidemiological and genetic perspectives

BACKGROUND

Research suggests that Alopecia areata (AA) and Major Depressive Disorder (MDD) show substantial comorbidity. To date, no study has investigated the hypothesis that this is attributable to shared genetic aetiology.

OBJECTIVES

To investigate AA-MDD comorbidity on the epidemiological and molecular genetic levels.

METHODS

First, epidemiological analyses were performed using data from a cohort of adult German health insurance beneficiaries (n = 1.855 million) to determine the population-based prevalence of AA-MDD comorbidity. Second, analyses were performed to determine the prevalence of MDD in a clinical AA case-control sample with data on psychiatric phenotypes, stratifying for demographic factors to identify possible contributing factors to AA-MDD comorbidity. Third, the genetic overlap between AA and MDD was investigated using a polygenic risk score (PRS) approach and linkage disequilibrium score (LDSC) regression. For PRS, summary statistics from a large MDD GWAS meta-analysis (PGC-MD2) were used as the training sample, while a Central European AA cohort, including the above-mentioned AA patients, and an independent replication US-AA cohort were used as target samples. LDSC was performed using summary statistics of PGC-MD2 and the largest AA meta-analysis to date.

RESULTS

High levels of AA-MDD comorbidity were reported in the population-based (MDD in 24% of AA patients), and clinical samples (MDD in 44% of AA patients). MDD-PRS explained a modest proportion of variance in AA case-control status (R²  = 1%). This signal was limited to the major histocompatibility complex (MHC) region on chromosome 6. LDSC regression (excluding MHC) revealed no significant genetic correlation between AA and MDD.

CONCLUSIONS

As in previous research, AA patients showed an increased prevalence of MDD. The present analyses suggest that genetic overlap may be confined to the MHC region, which is implicated in immune function. More detailed investigation is required to refine understanding of how the MHC is involved in the development of AA and MDD comorbidity.

High tumour mutational burden and EGFR/MAPK pathway activation are therapeutic targets in metastatic porocarcinoma

BACKGROUND

Eccrine porocarcinoma (EPC) is a rare skin cancer arising from the eccrine sweat glands. Due to the lack of effective therapies, metastasis is associated with a high mortality rate.

OBJECTIVES

To investigate the drivers of EPC progression.

METHODS

We carried out genomic and transcriptomic profiling of metastatic EPC (mEPC), validation of the observed alterations in an EPC patient-derived cell line, confirmation of relevant observations in a large patient cohort of 30 tumour tissues, and successful treatment of a patient with mEPC under the identified treatment regimens.

RESULTS

mEPC was characterized by a high tumour mutational burden (TMB) with an ultraviolet signature, widespread copy number alterations and gene expression changes that affected cancer-relevant cellular processes such as cell cycle regulation and proliferation, including a pathogenic TP53 (tumour protein 53) mutation, a copy number deletion in the CDKN2A (cyclin dependent kinase inhibitor 2A) region and a CTNND1/PAK1 [catenin delta 1/p21 (RAC1) activated kinase 1] gene fusion. The overexpression of EGFR (epidermal growth factor receptor), PAK1 and MAP2K1 (mitogen-activated protein kinase kinase 1; also known as MEK1) genes translated into strong protein expression and respective pathway activation in the tumour tissue. Furthermore, a patient-derived cell line was sensitive to EGFR and MEK inhibition, confirming the functional relevance of the pathway activation. Immunohistochemistry analyses in a large patient cohort showed the relevance of the observed changes to the pathogenesis of EPC. Our results indicate that mEPC should respond to immune or kinase inhibitor therapy. Indeed, the advanced disease of our index patient was controlled by EGFR-directed therapy and immune checkpoint inhibition for more than 2 years.

CONCLUSIONS

Molecular profiling demonstrated high TMB and EGFR/MAPK pathway activation to be novel therapeutic targets in mEPC.

Gene expression profiling in aggressive digital papillary adenocarcinoma sheds light on the architecture of a rare sweat gland carcinoma

BACKGROUND

Sweat gland carcinomas are rare cutaneous adnexal malignancies. Aggressive digital papillary adenocarcinoma (ADPA) represents a very rare subentity, thought to arise almost exclusively from the sweat glands of the fingers and toes. The aetiology of sweat gland carcinomas and ADPA is largely unknown. ADPAs are most likely driven by somatic mutations. However, somatic mutation patterns are largely unexplored, creating barriers to the development of effective therapeutic approaches to the treatment of ADPA.

OBJECTIVES

To investigate the transcriptome profile of ADPA using a sample of eight formalin-fixed, paraffin-embedded tissue samples of ADPA and healthy control tissue.

METHODS

Transcriptome profiling was performed using the Affymetrix PrimeView Human Gene Expression Microarray and findings were validated via reverse transcription of RNA and real-time quantitative polymerase chain reaction.

RESULTS

Transcriptome analyses showed increased tumour expression of 2266 genes, with significant involvement of cell cycle, ribosomal and crucial cancer pathways. Our results point to tumour overexpression of FGFR2 (P = 0·001).

CONCLUSIONS

The results indicate the involvement of crucial oncogenic driver pathways, highlighting cell cycle and ribosomal pathways in the aetiology of ADPA. Suggested tumour overexpression of FGFR2 raises the hope that targeting the fibroblast growth factor (FGF)/FGF receptor axis might be a promising treatment for ADPA and probably for the overall group of sweat gland carcinomas.

A novel KRT86 mutation in a Turkish family with monilethrix, and identification of maternal mosaicism

BACKGROUND

Monilethrix is a rare monogenic dystrophic hair loss disorder with high levels of intrafamilial and interfamilial variability. It is characterized by diffuse occipital or temporal alopecia, hair fragility and follicular hyperkeratosis of the occipital region. Mutations in the keratin genes KRT81, KRT83 and KRT86 lead to autosomal dominant monilethrix, whereas mutations in the desmoglein 4 gene (DSG4) cause an autosomal recessive form.

AIM

To identify the mutation in a consanguineous Turkish family with three affected children and apparently unaffected parents.

METHODS

Sequencing analysis of the genes DSG4 and KRT86 was performed. SNaPshot analysis was conducted to quantify the proportion of cells carrying the KRT86 mutation and to confirm maternal mosaicism of KRT86.

RESULTS

No pathogenic mutation was found by sequencing analysis of DSG4; however, analysis of KRT86 revealed a novel mutation, c.1231G>T;p.Glu411*, in exon 7 in the three affected children and their mother. The mutation signal was weaker in the mother than in the three siblings, and SNaPshot analysis revealed substantial mutation-level variation between the children and their mother.

CONCLUSIONS

Our results extend the spectrum of KRT86 mutations and indicate KRT86 mosaicism in the family examined. This study is the first, to our knowledge, to describe mosaicism for a monogenic hair loss disorder, and suggests that mosaicism leads to a mild manifestation of monilethrix.

Investigation of the male pattern baldness major genetic susceptibility loci AR/EDA2R and 20p11 in female pattern hair loss

BACKGROUND

The aetiology of female pattern hair loss (FPHL) is largely unknown. However, it is hypothesized that FPHL and male pattern baldness (AGA) share common susceptibility alleles. The two major susceptibility loci for AGA are the androgen receptor (AR)/ectodysplasin A2 receptor (EDA2R) locus on the X-chromosome, and a locus on chromosome 20p11, for which no candidate gene has yet been identified.

OBJECTIVES

To examine the role of the AR/EDA2R and 20p11 loci in the development of FPHL using 145 U.K. and 85 German patients with FPHL, 179 U.K. supercontrols and 150 German blood donors.

METHODS

Patients and controls were genotyped for 25 single nucleotide polymorphisms (SNPs) at the AR/EDA2R locus and five SNPs at the 20p11 locus.

RESULTS

Analysis of the AR/EDA2R locus revealed no significant association in the German sample. However, a nominally significant association for a single SNP (rs1397631) was found in the U.K. sample. Subgroup analysis of the U.K. patients revealed significant association for seven markers in patients with an early onset (P = 0·047 after adjustment for the testing of multiple SNPs by Monte Carlo simulation). No significant association was obtained for the five 20p11 variants, either in the overall samples or in the analysis of subgroups.

CONCLUSIONS

The observed association suggests that the AR/EDA2R locus confers susceptibility to early-onset FHPL. Our results do not implicate the 20p11 locus in the aetiology of FPHL.

Identification of a U2HR gene mutation in Turkish families with Marie Unna hereditary hypotrichosis

Marie Unna hereditary hypotrichosis (MUHH) is an autosomal dominant form of isolated alopecia. The disorder is characterized by the absence or scarcity of scalp hair, eyebrows and eyelashes at birth. Coarse wiry hair begins to grow during childhood, but this is followed by progressive hair loss, which usually begins around puberty. A recent study identified mutations in U2HR, an inhibitory upstream open reading frame in the 5'-untranslated region of the human hairless gene. We investigated three reportedly unrelated Turkish multigeneration families with MUHH. Using direct sequencing of U2HR we were able to identify the c. 2T>A (p.M1K) mutation in one index patient of each family. The mutation cosegregates perfectly with the disease in all members of the families. To our knowledge, this is the first time that a mutation in U2HR has been identified in families from the Middle East. The observation of a common mutation is suggestive of a possible founder effect.

The TRAF1/C5 locus confers risk for familial and severe alopecia areata

BACKGROUND

Alopecia areata (AA) is a common hair loss disorder with a complex mode of inheritance. Autoimmune mechanisms are presumed to be crucial aetiologically. It is plausible that a number of autoimmune disorders may share a common genetic background. This phenomenon has been demonstrated in previous studies, which have shown an overlap of susceptibility alleles between AA and other autoimmune disorders. Recent studies have shown that genetic variants on the TRAF1/C5 (tumor necrosis factor receptor-associated factor 1, complement component 5) locus confer susceptibility to rheumatoid arthritis (RA).

OBJECTIVES

To examine the role of the TRAF1/C5 locus in the development of AA using a large sample of 1,195 patients with AA and 1280 controls.

METHODS

We genotyped the two most significant single nucleotide polymorphisms (SNPs) (rs10818488, rs2416808) from a former RA candidate gene study. After having obtained evidence for association, we performed a fine-mapping study and genotyped the locus with an additional 27 SNPs.

RESULTS

While no significant result was obtained for the overall sample, rs2416808 showed significant associations in the analysis of the subgroups with severe AA and with a positive family history. The most significant P-value for rs2416808 was in familial cases (P = 0.004, P(corr) = 0.026). The fine mapping revealed significant associations for four additional SNPs in the analysis of subgroups, with rs2416808 remaining the most significant marker.

CONCLUSIONS

Our results point to the involvement of the TRAF1/C5 locus in the aetiology of familial and severe AA, and provide further support for a shared aetiology between AA and other autoimmune disorders.

The R620W polymorphism in PTPN22 confers general susceptibility for the development of alopecia areata

BACKGROUND

The functional R620W (c.1858C>T) variant of the protein tyrosine phosphatase nonreceptor 22 gene (PTPN22) has been associated with a variety of autoimmune disorders. A recent study has suggested that R620W also contributes to the severe form of alopecia areata (AA).

OBJECTIVES

We sought to replicate the finding of an association between PTPN22 and severe AA. In addition, we wanted to study the effect of PTPN22 on the general risk to develop AA and on other subtypes of AA (mild AA, early/late age at onset, positive/negative family history).

METHODS

The R620W variant was genotyped in a large case-control sample of Belgian-German origin with 435 patients and 628 controls.

RESULTS

Significant results were obtained for the overall collective of patients with AA (P=0.007). Subdividing the sample according to severity of AA, family history and age at onset, we detected lowest P-values for patients with the severe form of AA (Pcorr=0.036), with a positive family history (Pcorr=0.042) and with an age at onset<or=20 years (Pcorr=0.048).

CONCLUSIONS

Our results suggest the R620W variant of PTPN22 as a general risk factor in AA with the strongest effect observed among patients with a severe type of AA, a positive family history or an early onset of disease.

Moderate glucose deprivation preconditions myocardium against infarction

Glucose-free perfusion preconditions myocardium against the consequences of subsequent ischemia. We investigated whether mitochondrial ATP-sensitive potassium (mK (ATP)) channels are involved in preconditioning by glucose deprivation, and whether moderate glucose deprivation also preconditions myocardium. Isolated rat hearts underwent 30 min of no-flow ischemia followed by 1 h reperfusion. Controls were not further treated. Three groups were preconditioned by perfusion with 0, 40 or 80 mg/dl (0, 2.22, 4.44 mmol/l) glucose (correction of osmotic pressure by addition of urea) for 10 min followed by 10 min perfusion with normal buffer (150 mg/dl, or 8.33 mmol/l glucose) before the ischemia reperfusion protocol. In one group, 100 micromol/l of the mK (ATP) channel blocker 5-HD was added to the glucose-free perfusate. Two groups were treated with 5-HD or urea before ischemia without preconditioning. Left ventricular developed pressure and maximum ischemic contracture (82 +/- 21 mmHg) were similar in all groups. Mean left ventricular developed pressure was 100 +/- 16 mm Hg under baseline conditions, and poorly recovered to 8 +/- 11 mm Hg during reperfusion. Preconditioning with 0 and 40 mg/dl glucose containing buffer reduced infarct size from 41 +/- 10% (control) to 23 +/- 12% (p = 0.02) and 26 +/- 8% (p = 0.011). The 5-HD blocked preconditioning by glucose deprivation (38 +/- 9%, p = 0.04) while 80 mg/dl glucose, 5-HD and urea had no effect on infarct size (39 +/- 9%; 38 +/- 13%; 37 +/- 8%; p = 1.0 each). We conclude that transient severe glucose deprivation and moderate glucose deprivation preconditions the isolated rat heart. Preconditioning by complete glucose deprivation depends on the opening of mK (ATP) channels.