Novel and recurrent ATP2A2 mutations in Japanese patients with Darier's disease.

Darier's disease (DD, keratosis follicularis: OMIM#124200) is an autosomal dominant skin disorder characterized by multiple dark brown keratotic plaques and warty papules covered by thick crusts. Most cases of DD are caused by mutations in ATP2A2, which is expressed in both the skin and the brain. ATP2A2 encodes the cardiac muscle SERCA2a protein and the ubiquitously expressed SERCA2b. SERCA2 plays an important role as a calcium pump. It is thought that a mutation in ATP2A2 causes dyskeratosis and abnormality of cell-cell adhesion. Here, we report five DD patients from five independent families who presented or were referred to the Nagoya University Hospital in the past five years. We detected five mutations in ATP2A2, including a previously unreported mutation. We observed no apparent genotype/phenotype correlation between types and sites of the ATP2A2 mutations and DD phenotypes in the present series of DD patients. Genetic diagnosis from ATP2A2 mutation search is useful for the definite diagnosis of DD, although it is difficult to predict the severity and prognosis of skin symptoms from the results of the ATP2A2 mutation analysis in DD patients.

Histological Classification and Differential Diagnosis of Nonepisodic Angioedema With Eosinophilia: A Clinicopathologic Study of 12 Cases With Literature Review.

Nonepisodic angioedema with eosinophilia (NEAE) is a rare condition characterized with monoepisodic angioedema, a nonfebrile state, eosinophilia, normal serum IgM levels, and lack of internal organ involvement. The histology of this disease is not yet well known. The purpose of this study was to characterize the histopathologic features of NEAE. Twelve cases of clinically confirmed NEAE were retrieved from 6 institutions, and these cases were reviewed regarding the clinical data and histopathology, particularly regarding granulomatous lesions. The authors demonstrated that the histology of NEAE can be classified into 3 patterns that of eosinophilic granulomatous panniculitis (7/12 cases), eosinophilic dermatitis without granuloma formation (3/12 cases), and invisible dermatosis (2/12 cases). Six of the 7 granulomatous cases showed the characteristic eosinophilic granulomatous lesions containing individual necrotic adipocytes with membranous fat changes, which could be a differential clue to the diagnosis of NEAE. Review of the previously reported cases (n = 37) revealed that the histological classification could be adaptable to these reported cases. The authors should recognize the histological variation of NEAE and distinguish it from the histological mimickers, including eosinophilic granulomatosis with polyangiitis, erythema nodosum, hypereosinophilic syndrome, and episodic angioedema with eosinophilia.

Highly prevalent LIPH founder mutations causing autosomal recessive woolly hair/hypotrichosis in Japan and the genotype/phenotype correlations.

Mutations in LIPH cause of autosomal recessive woolly hair/hypotrichosis (ARWH), and the 2 missense mutations c.736T>A (p.Cys246Ser) and c.742C>A (p.His248Asn) are considered prevalent founder mutations for ARWH in the Japanese population. To reveal genotype/phenotype correlations in ARWH cases in Japan and the haplotypes in 14 Japanese patients from 14 unrelated Japanese families. 13 patients had woolly hair, and 1 patient had complete baldness since birth. An LIPH mutation search revealed homozygous c.736T>A mutations in 10 of the patients. Compound heterozygous c.736T>A and c.742C>A mutations were found in 3 of the patients, and homozygous c.742C>A mutation in 1 patient. The phenotype of mild hypotrichosis with woolly hair was restricted to the patients with the homozygous c.736T>A mutation. The severe phenotype of complete baldness was seen in only 1 patient with homozygous c.742C>A. Haplotype analysis revealed that the alleles containing the LIPH c.736T>A mutation had a haplotype identical to that reported previously, although 4 alleles out of 5 chromosomes containing the LIPH c.742C>A mutation had a different haplotype from the previously reported founder allele. These alleles with c.742C>A are thought to be the third founder LIPH mutation causing ARWH. To accurately determine the prevalence of the founder mutations, we investigated allele frequencies of those mutations in 819 Japanese controls. Heterozygous c.736T>A mutations were found in 13 controls (allele frequency: 0.0079; carrier rate: 0.016), and heterozygous c.742C>A mutations were found in 2 controls (allele frequency: 0.0012; carrier rate: 0.0024). In conclusion, this study confirms the more accurate allele frequencies of the pathogenic founder mutations of LIPH and shows that there is a third founder mutation in Japan. In addition, the present findings suggest that the mutation patterns of LIPH might be associated with hypotrichosis severity in ARWH.

Whole-exome sequencing identifies ADAM10 mutations as a cause of reticulate acropigmentation of Kitamura, a clinical entity distinct from Dowling-Degos disease.

Reticulate acropigmentation of Kitamura (RAK) is a rare genetic disorder of cutaneous pigmentation with an autosomal dominant pattern of inheritance and a high penetration rate. The characteristic skin lesions are reticulate, slightly depressed pigmented macules mainly affecting the dorsa of the hands and feet, which first appear before puberty and subsequently expand to the proximal limb and the trunk. To identify mutations that cause RAK, we performed exome sequencing of four family members in a pedigree with RAK. Fifty-three SNV/Indels were considered as candidate mutations after some condition narrowing. We confirmed the mutation status in each candidate gene of four other members in the same pedigree to find the gene that matched the mutation status and phenotype of each member. A mutation in ADAM10 encoding a zinc metalloprotease, a disintegrin and metalloprotease domain-containing protein 10 (ADAM10), was identified in the RAK family. ADAM10 is known to be involved in the ectodomain shedding of various substrates in the skin. Sanger sequencing of four additional unrelated RAK patients revealed four additional ADAM10 mutations. We identified a total of three truncating mutations, a splice site mutation and a missense mutation in ADAM10. We searched for mutations in the KRT5 gene, a causative gene for the similar pigmentation disorder Dowling-Degos disease (DDD), in all the patients and found no KRT5 mutation. These results reveal that mutations in ADAM10 are a cause of RAK and that RAK is an independent clinical entity distinct from DDD.

Mutation analysis of the ADAR1 gene in dyschromatosis symmetrica hereditaria and genetic differentiation from both dyschromatosis universalis hereditaria and acropigmentatio reticularis.

Dyschromatosis symmetrica hereditaria (DSH) (also called "reticulate acropigmentation of Dohi") is a pigmentary genodermatosis of autosomal dominant inheritance. We have clarified for the first time four pathological mutations of the double-stranded RNA-specific adenosine deaminase gene (ADAR1 or DSRAD) in four DSH pedigrees. In this paper, we report 16 novel mutations containing six missense substitutions (p.V906F, p.K1003R, p.G1007R, p.C1036S, p.S1064F, p.R1078C), two splice site mutations (IVS2+2T>G, IVS8+2T>A), six frameshift mutations (p.H216fs, p.K433fs, p.G507fs, p.P727fs, p.V955fs, p.K1201fs), and two nonsense mutations (p.R426X, p.Q600X) found in Japanese patients with DSH. We did not establish any clear correlation between the clinical phenotypes and the genotypes of ADAR1 gene mutations in our examination of 16 cases plus four pedigrees. None of the different mutations identified in our studies of 20 cases suggested any founder effect. Furthermore, we did not identify any mutations in the ADAR1 gene of three patients with dyschromatosis universalis hereditaria or three patients with acropigmentatio reticularis, indicating that the two diseases are completely different from DSH, although they have sometimes been suggested to be phenotypical variations of DSH.