Dyschromatosis universalis hereditaria as an autosomal recessive disease in five members of one family

Dyschromatosis universalis hereditaria

Reticulate pigmentary dyschromatoses primarily include dyschromatosis universalis hereditaria (DUH), dyschromatosis symmetrica hereditaria (DSH) (Reticulate acropigmentation of Dohi), and unilateral dermatomal pigmentary dermatosis, which differ in their patterns of distribution. The disease was initially described by Ichikawa and Hiraga in Germany in 1933. The prevalence of DUH is 0.3 per 100,000 with a female preponderance. The skin lesions usually appear in infancy or early childhood and cease to progress beyond adolescence. The subtypes DUH 1 and DUH 3 are found to have autosomal dominant inheritance, which is the most common inheritance pattern, while DUH 2 has an autosomal recessive pattern. The most common gene involved in DUH is ABCB6, while the other genes include SASH 1, PER 3, and KITLG (DUH type 2). DUH is characterized by multiple irregular hyperpigmented macules interspersed with hypopigmented macules in a mottled pattern over the trunk and extremities. The face is involved in 50% of individuals. Rarely, it can also involve hairs, nails, mucous membranes, palms, and soles. Other varied presentations include localized forms, localization of lesions to sun-exposed areas, large macules, uniform palmar hypopigmentation, diffuse hyperpigmentation with spotty depigmented macules, and unilateral involvement. DUH has been reported to be associated with various cutaneous and systemic diseases. The authors have observed cases of DUH associated with hepatocellular carcinoma, solitary keratoacanthoma, and dermoid cyst. The various diagnostic modalities include dermoscopy, histopathology, electron microscopy, and targeted gene sequencing. Though various treatment modalities like NBUVB and lasers have been tried, no treatment is promising.

Retyping and molecular pathology diagnosis of dyschromatosis universalis hereditaria

Dyschromatosis universalis hereditaria (DUH) is characterized by diffuse symmetrically distributed hypopigmented macules mixed with hyperpigmentation. DUH is divided into three types by Online Mendelian inheritance in man (OMIM) that is, DUH1 (OMIM 127500), DUH2 (OMIM 612715) and DUH3 (OMIM 615402) according to the different linkage regions. Although each condition possesses corresponding phenotypic characteristics and the prognosis for each is somewhat different, these disorders are highly overlapped and difficult to differentiate in the clinical setting. Our latest study reveals a novel DUH subtype that presents a mild phenotype of pigmentation anomalies and is named PER3rs772027021 SNP related DUH or DUH4 by us, which make the DUH subtype can be further retyped. Heterozygous distribution or mosaic-like distribution of melanin is a newly discovered pathological features that is uniquely demonstrated in the affected layers of DUH1 and DUH4 patients. In this review, DUH is further divided into four subtypes according the causative genes and their mutational sites, and the mutation regions described in the previous reports. To make an accurate diagnosis, we suggest that Sanger sequencing or the target region sequencing (TRS) to the candidate causative genes related melanogenesis may be the most effective and convenient method of clinical diagnosis or/and prenatal diagnosis for DUH and DUH-like patients. More importantly, heterozygous distribution or mosaic-like distribution of melanin can be utilized for differential diagnosis of DUH. We also investigate the underlying molecular mechanism to form mosaic-like melanin in the affected layers of hyper- and/or hypo-pigmented macules from DUH1 and DUH4 patients. This review provides a molecular and pathological delineation of four types of DUH and aims to establish a concise diagnostic strategy to allow clinical dermatologists to make an accurate diagnosis.

De novo mutation in KITLG gene causes a variant of Familial Progressive Hyper- and Hypo-pigmentation (FPHH)

Familial Progressive Hyper‐ and Hypopigmentation is a pigmentary disorder characterized by a mix of hypo‐ and hyperpigmented lesions, café‐au‐lait spots and hypopigmented ash‐leaf macules. The disorder was previously linked to KITLG and various mutations have been reported to segregate in different families. Furthermore, association between KITLG mutations and malignancies was also suggested. Exome and SANGER sequencing were performed for identification of KITLG mutations. Functional in silico analyses were additionally performed to assess the findings. We identified a de novo mutation in exon 4 of KITLG gene causing NM_000899.4:c.[329A>T] (chr12:88912508A>T) leading to NP_000890.1:p.(Asp110Val) substitution in the 3rd alpha helix. It was predicted as pathogenic, located in a conserved region and causing an increase in hydrophobicity in the KITLG protein. Our findings clearly confirm an additional hot spot of KITLG mutations in the 3rd alpha helix, which very likely increases the risk of malignancies. To our knowledge the present study provides the strongest evidence of association of the KITLG mutation with both Familial Progressive Hyper‐ and Hypopigmentation and malignancy due to its’ location on somatic cancer mutation locus. Additionally we also address difficulties with classification of the unique phenotype and propose a subtype within broader diagnosis.

Two novel SASH1 mutations in Chinese families with dyschromatosis universalis hereditaria

Background

Dyschromatosis universalis hereditaria (DUH) is a rare genodermatosis characterized by hyper‐ and hypo‐pigmented macules on the face, trunk, and extremities. The condition causes severe cosmetic problem which can lead to significant psychological distress to the patients and bear a negative impact on society. DUH is a condition with genetic heterogeneity. The SASH1 gene was recently identified as pathogenic genes in DUH patients.

Methods

Two families clinically diagnosed with dyschromatosis universalis hereditaria were enrolled. Whole‐exome sequencing combined with Sanger sequencing and bioinformatics analysis was performed in the probands. MutationTaster, CADD, SIFT, PolyPhen‐2, and LRT software, and The American College of Medical Genetics and Genomics Standards and Guidelines were employed to assess the pathogenicity of detected missense mutations. One hundred healthy unrelated Chinese individuals were used as controls. All participants signed an informed consent form.

Results

Genetic screening revealed a heterozygous SASH1 c.1547G>A (p.Ser516Asn) mutation for patients in family 1, and SASH1 c.1547G>T (p.Ser516Ile) for family 2. Both such de novo mutations are located in a highly conserved SLY domain in SASH1, have not been previously reported in any publication, and were not detected in any control databases.

Conclusions

The novel heterozygous mutations, SASH1 c.1547G>A and c.1547G>T, are likely responsible for the DUH phenotype in these two families. Our study expands the mutation spectrum of DUH. Whole‐exome sequencing showed its efficiency in the diagnostic of hereditary skin disorders.

Updated review of genetic reticulate pigmentary disorders

Reticulate pigmentary disorders are a group of disorders characterized by hyper- and/or hypopigmented macules with varying sizes and amounts of pigment. Some of the disorders are heritable, such as Dowling-Degos disease, dyschromatosis universalis hereditaria, dyschromatosis symmetrica hereditaria, reticulate acropigmentation of Kitamura and X-linked reticulate pigmentary disorder. Although each condition possesses unique phenotypic characteristics and the prognosis for each is somewhat different, there is a large degree of overlap between the disorders and therefore they are difficult to differentiate in the clinical setting. This updated review provides a clinical and molecular delineation of these genetic reticulate pigmentary disorders and aims to establish a concise diagnostic strategy to allow clinical dermatologists to make an accurate diagnosis, as well as to provide useful information for clinical and genetic counselling.

Dyschromias: A Series of Five Interesting Cases from India

Dyschromatosis is a pigmentary genodermatosis which presents with hyper and hypopigmented skin lesions giving a mottled appearance. It is a rare entity in India reported mainly in the East Asian population. Classically, two forms have been described; dyschromatosis universalis hereditaria (DUH) and dyschromatosis symmetrica hereditaria. Here we report four cases of DUH and one case of dyschromatosis symmetrica hereditaria from India.

A case of dyschromatosis universalis hereditaria with adermatoglyphia: A rare association

Dyschromatosis universalis hereditaria (DUH) is a rare, autosomal dominant genodermatosis with a peculiar reticulate pigmentary change, consisting of hyperpigmented macules mingled with hypopigmented lesions to give an overall impression of mottling. We herein report a case of DUH with adermatoglyphia in a young male with family history of the disorder.

Dyschromatosis universalis hereditaria: Infrequent genodermatoses in India

Dyschromatosis universalis hereditaria (DUH) is a rare genodermatosis reported initially and mainly in Japan. However, subsequent cases have been reported from other countries. We report a case of DUH in a south Indian woman with a positive family history with cosmetic disfigurement and severe psychological impairment.

Reticulate dermatoses

The term "reticulate" is used for clinical description of skin lesions that are configured in a net-like pattern. Many primary and secondary dermatoses present in such patterns involving specific body sites. Certain cutaneous manifestations of systemic diseases or genodermatoses also present in such manner. This review classifies and describes such conditions with reticulate lesions and briefly, their associated features.

Novel mutations of ABCB6 associated with autosomal dominant dyschromatosis universalis hereditaria

Objective

Dyschromatosis universalis hereditaria (DUH) is a rare heterogeneous pigmentary genodermatosis, which was first described in 1933. The genetic cause has recently been discovered by the discovery of mutations in ABCB6. Here we investigated a Chinese family with typical features of autosomal dominant DUH and 3 unrelated patients with sporadic DUH.

Methods

Skin tissues were obtained from the proband, of this family and the 3 sporadic patients. Histopathological examination and immunohistochemical analysis of ABCB6 were performed. Peripheral blood DNA samples were obtained from 21 affected, 14 unaffected, 11 spouses in the family and the 3 sporadic patients. A genome-wide linkage scan for the family was carried out to localize the causative gene. Exome sequencing was performed from 3 affected and 1 unaffected in the family. Sanger sequencing of ABCB6 was further used to identify the causative gene for all samples obtained from available family members, the 3 sporadic patients and a panel of 455 ethnically-matched normal Chinese individuals.

Results

Histopathological analysis showed melanocytes in normal control’s skin tissue and the hyperpigmented area contained more melanized, mature melanosomes than those within the hypopigmented areas. Empty immature melanosomes were found in the hypopigmented melanocytes. Parametric multipoint linkage analysis produced a HLOD score of 4.68, with markers on chromosome 2q35-q37.2. A missense mutation (c.1663 C>A, p.Gln555Lys) in ABCB6 was identified in this family by exome and Sanger sequencing. The mutation perfectly cosegregated with the skin phenotype. An additional mutation (g.776 delC, c.459 delC) in ABCB6 was found in an unrelated sporadic patient. No mutation in ABCB6 was discovered in the other two sporadic patients. Neither of the two mutations was present in the 455 controls. Melanocytes showed positive immunoreactivity to ABCB6.

Conclusion

Our data add new variants to the repertoire of ABCB6 mutations with DUH.

Mutations in POFUT1, encoding protein O-fucosyltransferase 1, cause generalized Dowling-Degos disease

Dowling-Degos disease (DDD), or reticular pigmented anomaly of the flexures, is a type of rare autosomal-dominant genodermatosis characterized by reticular hyperpigmentation and hypopigmentation of the flexures, such as the neck, axilla, and areas below the breasts and groin, and shows considerable heterogeneity. Loss-of-function mutations of keratin 5 (KRT5) have been identified in DDD individuals. In this study, we collected DNA samples from a large Chinese family affected by generalized DDD and found no mutation of KRT5. We performed a genome-wide linkage analysis of this family and mapped generalized DDD to a region between rs1293713 and rs244123 on chromosome 20 [corrected]. By exome sequencing, we identified nonsense mutation c.430G>T (p.Glu144(∗)) in POFUT1, which encodes protein O-fucosyltransferase 1, in the family. Study of an additional generalized DDD individual revealed the heterozygous deletion mutation c.482delA (p.Lys161Serfs(∗)42) in POFUT1. Knockdown of POFUT1 reduces the expression of NOTCH1, NOTCH2, HES1, and KRT5 in HaCaT cells. Using zebrafish, we showed that pofut1 is expressed in the skin and other organs. Morpholino knockdown of pofut1 in zebrafish produced a phenotype characteristic of hypopigmentation at 48 hr postfertilization (hpf) and abnormal melanin distribution at 72 hpf, replicating the clinical phenotype observed in our DDD individuals. At 48 and 72 hpf, tyrosinase activities decreased by 33% and 45%, respectively, and melanin protein contents decreased by 20% and 25%, respectively. Our findings demonstrate that POFUT1 mutations cause generalized DDD. These results strongly suggest that the protein product of POFUT1 plays a significant and conserved role in melanin synthesis and transport.

The genetic determination of skin pigmentation: KITLG and the KITLG/c-Kit pathway as key players in the onset of human familial pigmentary diseases

Cutaneous pigmentation is regulated by a complex melanogenic network in which skin cells synthesize growth factors and cytokines. Mutations in genes encoding these regulators modify their expression and/or functionality, leading to altered signaling pathways and contributing to altered skin phenotypes. In this issue, Amyere et al. report a genome-wide analysis of seven families with familial progressive hyperpigmentation and hypopigmentation, identifying three new mutations in KITLG. The study underlines the relevance of investigating candidate genes implicated in the onset of pigmentary disorders. Furthermore, Amyere et al. suggest that different pigmentary diseases can result from the same mutation or different mutations in the same gene, and they offer hope for the development of new and efficacious treatment strategies.

Dyschromatosis universalis hereditaria in a young Nigerian female

Dyschromatosis universalis hereditaria (DUH) is a clinically heterogeneous disorder that shows generalized mottled pigmentation. It occurs most commonly in Japanese persons, with sporadic reports from South Africa, India, and Iraq. Histopathology reveals a variable degree of pigmentary incontinence. Although the precise etiology of this disorder is not yet known, the clinicopathological findings implicate an inherent abnormality of melanosomes or melanin processing. We describe a case in a young Nigerian girl.

Dyschromatosis universalis hereditaria: evidence for autosomal recessive inheritance and identification of a new locus on chromosome 12q21-q23

Dyschromatosis universalis hereditaria (DUH) and dyschromatosis symmetrica hereditaria (DSH) are pigmentary dermatoses most commonly seen in Japan. Both disorders usually show autosomal dominant inheritance, although in some cases autosomal recessive inheritance was reported. DSH was mapped to chromosome 1q21.3, and mutations in the gene ADAR (DSRAD) were identified in Japanese, Chinese and Taiwanese families with autosomal dominant DSH. A second locus for dyschromatosis was mapped on chromosome 6q24.2-q25.2 in two Chinese families initially reported to be affected with DSH, but later suggested to have autosomal dominant DUH. The aim of this study was to investigate whether one of these two loci is involved in the development of DUH in a consanguineous Bedouin family from Saudi Arabia with four affected and three unaffected sibs, clearly pointing to autosomal recessive inheritance. After excluding mutations in ADAR and linkage to the candidate regions on chromosomes 1 and 6, we performed an single nucleotide polymorphism-based genome-wide scan for linkage with other loci. Under the assumption of autosomal recessive inheritance, we have identified a new locus for dyschromatosis on chromosome 12q21-q23 in this Arab family with a maximum logarithm of the odds (LOD) score of 3.4, spanning a distance of 18.9 cM. Our study revealed the first locus for autosomal recessive DUH and supports recent evidence that DSH and DUH are genetically distinct disorders.