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.

[Hair anomalies in syndromic disorders]. / Haaranomalien bei syndromalen Erkrankungen.

Genetic diseases with hyper- and hypotrichosis are very heterogeneous, both clinically and genetically. This is especially true for ectodermal dysplasias but also for hereditary syndromes in which, beyond abnormal hair growth, other structures and organs are affected. In this review, we discuss distinct diseases with excessive and reduced hair growth, focusing on the clinical hallmarks and underlying genetic defects.

Isolated recessive nail dysplasia caused by FZD6 mutations: report of three families and review of the literature.

Congenital abnormalities of the nail are rare conditions that are most frequently associated with congenital ectodermal syndromes involving several of the epidermal appendages including the skin, teeth, hair and nails. Isolated recessive nail dysplasia (IRND) is much rarer but has recently been recognized as a condition resulting in 20-nail dystrophy in the absence of other cutaneous or extracutaneous findings. A few case reports have identified mutations in the Frizzled 6 (FZD6) gene in families presenting with abnormal nails consistent with IRND. These reports have highlighted the role of Wnt-FZD signalling in the process of nail formation. We report three families presenting with features of IRND, in whom we identified mutations in FZD6, including one previously unreported mutation.

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.

[Alopecia and hypotrichosis in childhood: clinical features and diagnosis]. / Alopezien und Hypotrichosen im Kindesalter: Klinik und Diagnostik.

The monogenic inherited isolated alopecias comprise a group of clinically and genetically heterogeneous disorders with decreased or absent hair. Clinical classification of the isolated alopecias is based upon the onset of the disorder, the regions affected, and the structure of the hair shaft. Men and women are equally affected, and the mode of inheritance is autosomal dominant or autosomal recessive. Therapy does not exist for these rare forms of alopecia. However, molecular genetic diagnosis is possible for the identification of the genetic causes and for the specification of the recurrence risk. Since the identification of the keratin gene KRT86 as a cause of the so called monilethrix in 1997, mutations in eleven other genes have been identified for various isolated alopecias. These include other keratin genes for monilethrix, the HR gene for atrichia congenita, the genes CDSN, APCDD1 and SNRPE for the autosomal dominant form of hypotrichosis simplex, and the genes DSG4, LIPH and LPAR6 for the autosomal recessive forms of hypotrichosis as well as U2HR for hypotrichosis type Marie Unna. Molecular genetic and pathophysiological studies of these rare disorders of hair development have significantly contributed to our understanding of the basic mechanisms of hair loss as well as the physiological mechanisms of hair growth.

A premature termination mutation in a patient with Lowe syndrome without congenital cataracts: dropping the "O" in OCRL.

The oculocerebrorenal syndrome of Lowe is an X-linked recessive disorder characterized by the triad of congenital cataracts, mental retardation and a renal proximal tubulopathy. Although severity of phenotype might vary, congenital cataracts are part of the definition of this rare disorder.We report a 13-year-old patient with the typical cerebrorenal phenotype of Lowe syndrome, that had remained undiagnosed due to absence of any ocular involvement. OCRL gene analysis was carried.DNA analysis revealed a c.C760T (p.Gln199X) nonsense mutation in exon 8 expected to cause complete disruption of OCRL function. After sequencing the parents of the index patient and his maternal grandparents, this mutation turned out to be de novo in the mother. Furthermore, a silent variant (p.Arg35=) was identified in exon 2, that could also be identified in the mother and her 3 sisters, but not in the grandparents assuming germ cell mosaicism in either of the grandparents. RNA analysis from the patient's lymphocytes revealed presence of full-length OCRL transcripts. Western blotting from lymphocyte samples failed to detect OCRL protein even in controls.Our findings extend the phenotypic spectrum caused by OCRL mutations and illustrate that there may be selective organ involvement in Lowe syndrome.

Investigation of selected cytokine genes suggests that IL2RA and the TNF/LTA locus are risk factors for severe alopecia areata.

BACKGROUND: Alopecia areata (AA) is the second most common cause of hair loss in humans, and has a genetically complex inheritance. The hypothesis that AA is autoimmune in nature is supported by previous studies. These report an association with specific HLA alleles, as well as genetic variants of other genes implicated in autoimmunity, such as various cytokine genes. However, these cannot yet be considered proven susceptibility loci, as many of these association findings were derived from small patient samples. OBJECTIVES: To investigate the association between AA and selected cytokine genes using a sample of 768 patients with AA and 658 controls of Central European origin. METHODS: Eleven single-nucleotide polymorphisms (SNPs) from cytokine genes implicated in previous AA studies were genotyped. These genes were IL1B, IL1A, IL1RN, MIF, IFNG and the TNF/LTA gene region. We also genotyped 15 SNPs selected from cytokine genes that have shown significant association with other autoimmune diseases. These genes were IL10, IL36RN, IL12B, IL6, IL2, IL23, IL2RA and IL4R. RESULTS: Significant association was found for two variants within both IL2RA and TNF/LTA. In the overall sample, the most significant results were obtained for the IL2RA variant rs706778 (P = 0·00038) and the TNF/LTA locus variant rs1800629 (P = 0·0017). In subgroup analyses, according to severity, age at onset and family history these effects were stronger in the severely affected patients, with the lowest P-values being obtained for rs706778 (P = 3·8 × 10(-6) ). CONCLUSIONS: Our results point to the involvement of IL2RA and the TNF/LTA region in the aetiology of AA, in particular severe AA, and provide further support for the hypothesis that AA is autoimmune in nature.