Dyschromatosis

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.

Inherited Reticulate Pigmentary Disorders

Reticulate pigmentary disorders (RPDs) are a group of inherited and acquired skin conditions characterized by hyperpigmented and/or hypopigmented macules. Inherited RPDs include dyschromatosis symmetrica hereditaria (DSH), dyschromatosis universalis hereditaria (DUH), reticulate acropigmentation of Kitamura (RAK), Dowling-Degos disease (DDD), dyskeratosis congenita (DKC), Naegeli-Franceschetti-Jadassohn syndrome (NFJS), dermatopathia pigmentosa reticularis (DPR), and X-linked reticulate pigmentary disorder. Although reticulate pattern of pigmentation is a common characteristic of this spectrum of disorders, the distribution of pigmentation varies among these disorders, and there may be clinical manifestations beyond pigmentation. DSH, DUH, and RAK are mostly reported in East Asian ethnicities. DDD is more common in Caucasians, although it is also reported in Asian countries. Other RPDs show no racial predilection. This article reviews the clinical, histological, and genetic variations of inherited RPDs.

The PER3rs772027021 SNP induces pigmentation phenotypes of dyschromatosis universalis hereditaria

Dyschromatosis universalis hereditaria (DUH) is a pigmentary genodermatosis characterized by a mixture of hyperpigmented and hypopigmented macules distributed randomly over the body. Although Sterile Alpha motif- and SH3 domain-containing protein 1 (SASH1) and ATP-binding cassette subfamily B, member 6 (ABCB6) have been identified as causative genes for this disorder, some cases involve unknown pathogenic genes. In this study, whole-exome sequencing, data analysis, and Sanger sequencing were utilized for a four-generation extended Chinese family with DUH. A single-nucleotide polymorphism (SNP) (c. 517C > T (p.P173S), rs772027021) variant in exon 5 of Period Circadian Regulator 3 (PER3) (NM_001289861) was detected in each affected individual of the DUH family; the c. 517C > T SNP of PER3 (PER3^rs772027021 SNP) and a novel mutation in exon 14 of SASH1 (c. 1574C > G (p.T525R)) were both found in the proband. The affected individuals carrying PER3^rs772027021 SNP in this family demonstrated mild-pigmented phenotypes compared to those of the proband carrying PER3^rs772027021 SNP and SASH1 ^T525R mutation. Increased melanin synthesis was induced by PER3^rs772027021 SNP in the melanocytes of affected epithelial tissues. Mutated SASH1 or PER3^rs772027021 SNP alone or cooperation of mutation of SASH1 and PER3^rs772027021 SNP synergistically led to increased melanin synthesis and enhanced proliferation of melanoma cells in vitro. We also phenotypically characterized a commercially available zebrafish mutant line harboring the PER3^rs772027021 SNP to induce melanocyte proliferation in vivo. Our results are the first to reveal that this PER3 SNP may be pathogenic for a novel DUH subtype with mild hyperpigmented and/or hypopigmented phenotypes and that mutation of SASH1 and PER3 cooperatively promotes hyperpigmentation phenotypes. KEY MESSAGES: PER3 ^rs772027021 SNP is identified to be associated with hyperpigmentation and/or hypopigmentation phenotype and the novel pathogenic variant of PER3 ^rs772027021 SNP probably contributed the pathogenesis of DUH. SASH1^T525R mutation is confirmed to associate with DUH. A novel autosomal dominant inheritance DUH subtype with mild pigmentated phenotypes is caused by the PER3^rs772027021 SNP.

Primary Localized Cutaneous Amyloidosis of Keratinocyte Origin: An Update with Emphasis on Atypical Clinical Variants

Amyloid is a protein derived from at least 20 different substances. Once misfolded, it results in a group of cutaneous and systemic conditions. Primary localized cutaneous amyloidosis of keratinocyte origin is a very common subtype that can manifest either as lichen or macular amyloidosis, lacking systemic involvement. Lichen amyloidosis often presents as multiple hyperpigmented papules on the lower extremities whereas macular amyloidosis is classically characterized by dark brown rippled macules on the interscapular area. Review of the literature reveals that in addition to the classical presentation of primary localized cutaneous amyloidosis there exists a plethora of various manifestations that can be grouped into either geographic or morphologic categories. This review provides clinicians with the intimate knowledge of these presentations and summarizes the available treatment modalities.

[Hyperpigmentation]

The key diagnostic tool for hyperpigmentation is histopathology, which may be accompanied by certain laboratory tests. Hyperpigmentation may result from excess melanin (hypermelanosis), cutaneous iron deposits (hemosiderosis), cutaneous carotene deposits (carotenoderma), or cutaneous deposits of a substance not normally found in the skin (dyschromia). The different types of hypermelanosis may be classified as either localised or generalised. The former generally correspond to skin tumours and may form a cutaneous expression of complex syndromes, which most notably include cardiac abnormalities, or to pigmented forms of inflammatory and/or infectious dermatoses. Diffuse hypermelanosis is frequently a sign of systemic disease, generally metabolic or endocrine disease, or else it may result from pharmaceutical therapy. Herein we review the various causes of hyperpigmentation and the corresponding therapy.

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.

Differential Diagnosis of Two Chinese Families with Dyschromatoses by Targeted Gene Sequencing

Background:

The dyschromatoses are a group of disorders characterized by simultaneous hyperpigmented macules together with hypopigmented macules. Dyschromatosis universalis hereditaria (DUH) and dyschromatosis symmetrica hereditaria are two major types. While clinical and histological presentations are similar in these two diseases, genetic diagnosis is critical in the differential diagnosis of these entities.

Methods:

Three patients initially diagnosed with DUH were included. The gene test was carried out by targeted gene sequencing. All mutations detected on ADAR1 and ABCB6 genes were analyzed according to the frequency in control database, the mutation types, and the published evidence to determine the pathogenicity.

Results:

Family pedigree and clinical presentations were reported in 3 patients from two Chinese families. All patients have prominent cutaneous dyschromatoses involving the whole body without systemic complications. Different pathogenic genes in these patients with similar phenotype were identified: One novel mutation on ADAR1 (c. 1325C>G) and one recurrent mutation in ABCB6 (c. 1270T>C), which successfully distinguished two diseases with the similar phenotype.

Conclusion:

Targeted gene sequencing is an effective tool for genetic diagnosis in pigmentary skin diseases.

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.

Autosomal-recessive SASH1 variants associated with a new genodermatosis with pigmentation defects, palmoplantar keratoderma and skin carcinoma

SASH1 (SAM and SH3 domain-containing protein 1) is a tumor suppressor gene involved in the tumorigenesis of a spectrum of solid cancers. Heterozygous SASH1 variants are known to cause autosomal-dominant dyschromatosis. Homozygosity mapping and whole-exome sequencing were performed in a consanguineous Moroccan family with two affected siblings presenting an unclassified phenotype associating an abnormal pigmentation pattern (hypo- and hyperpigmented macules of the trunk and face and areas of reticular hypo- and hyperpigmentation of the extremities), alopecia, palmoplantar keratoderma, ungueal dystrophy and recurrent spinocellular carcinoma. We identified a homozygous variant in SASH1 (c.1849G>A; p.Glu617Lys) in both affected individuals. Wound-healing assay showed that the patient's fibroblasts were better able than control fibroblasts to migrate. Following the identification of SASH1 heterozygous variants in dyschromatosis, we used reverse phenotyping to show that autosomal-recessive variants of this gene could be responsible for an overlapping but more complex phenotype that affected skin appendages. SASH1 should be added to the list of genes responsible for autosomal-dominant and -recessive genodermatosis, with no phenotype in heterozygous patients in the recessive form, and to the list of genes responsible for a predisposition to skin cancer.

Amyloidosis cutis dyschromica

Background

Amyloidosis cutis dyschromica is a rarely documented variant of cutaneous amyloidosis. To date, only 26 cases have been reported.

Objective

The purpose of this study was to improve the clinical and histopathological data for this variant of amyloidosis and to highlight the immunohistochemical features of the disease. The published cases were also reviewed.

Methods

We performed a retrospective review of patients with amyloidosis cutis dyschromica in a single centre. The clinical, histopathological and immunohistochemical features were documented and analysed.

Observations

We described 10 cases of amyloidosis cutis dyschromica. Six of them were female. Five patients were from the same family, and the other 5 were sporadic. The distinguishing features of the clinical presentation included generalised mottled hyper- and hypopigmented macules, which were asymptomatic or mild pruritic. The typical onset of the lesions occurred in childhood (n = 7) and occasionally after puberty (n = 3). No evidence of systemic amyloidosis deposition was observed in these cases of amyloidosis cutis dyschromica. Amyloid deposits were observed in the papillary dermis and were positive for the Congo red stain. An immunohistochemical study showed that the amyloid expresses cytokeratins CK34βE12 and CK5/6.

Conclusions

We described the largest series of amyloidosis cutis dyschromica to date and reviewed the published patients. This rare disease is featured by generalised mottled hyper- and hypopigmented lesions, and it is a rare variant of primary cutaneous amyloidosis without evidence of systemic amyloid deposition. Positive staining for the cytokeratins CK34βE12 and CK5/6 in amyloidosis cutis dyschromica suggests that the amyloid is derived from keratinocytes.

Infancy- and childhood-onset dyschromatoses

The dyschromatoses are a group of pigmentary disorders characterized clinically by mixed and often guttate hypopigmented and hyperpigmented lesions. There are many conditions that present with dyschromatosis, including genodermatoses, inflammatory skin diseases, infections, drug and chemical use, and nutritional disorders. Some conditions have extracutaneous features. Poikiloderma (a combination of hypo- and hyperpigmentation with telangiectasia and atrophy) must be excluded. In this article, we describe the dyschromatoses typically presenting in infancy and childhood, most of which are genodermatoses. The approach we have taken in classifying them is based on organ involvement. We hope this article will serve as a guide for dermatologists to the recognition of these uncommon conditions.

Amyloidosis cutis dyschromica associated with atypical Parkinsonism, spasticity and motor weakness in a Pakistani female

Amyloidosis cutis dyschromica is a rare form of cutaneous amyloidosis in which there is deposition of keratinocyte-derived amyloid with involvement of almost the entire integument, leading to diffuse dyschromia without associated systemic abnormalities. We report the case of a 40-year-old female who presented with the onset of diffuse hyperpigmentation shortly after birth, which was followed by the widespread development of numerous 2-5 mm hypopigmented macules. Biopsy of the one of these macules revealed eosinophilic globular material in the papillary dermis with Congo red birefringence which also stained positively for high-molecular weight cytokeratin. Electron microscopy confirmed the presence of 11 nm hollow fibrils, consistent with amyloid. Similar clinical changes were noted in a younger male sibling. Both patients also suffered from an unexplained neurological disorder characterized by atypical Parkinsonism, spasticity and motor weakness. This association has not been shown before and may represent a heretofore unreported contiguous gene syndrome.

Dyschromatosis ptychotropica: an unusual pigmentary disorder in a boy with epileptic encephalopathy and progressive atrophy of the central nervous system-a novel entity?

The skin and the central nervous system are tissues of common ectodermal origin and share a close ontogenetic relationship. Genetic diseases primarily affecting both organ systems are regularly encountered in both dermatological and neurological settings. Here, we report on a boy with epileptic encephalopathy, severe intellectual disability, optic atrophy, and progressive cerebellar and supratentorial atrophy, reminiscent of progressive encephalopathy with edema and hypsarrythmia (PEHO) syndrome displaying a previously undescribed dyschromatosis in the form of progressive reticulate and mottled hyper- and hypopigmentation of the neck and the inguinal and axillary regions. We hypothesised that this combination of neurological and cutaneous findings has a common aetiology and represents a novel recognisable entity. Because of the unusual dermatological findings, we suggest the term dyschromatosis ptychotropica. Recognition of further cases may help elucidate the aetiology of this condition and give insight into the pathophysiology of both pigmentation disorders and epileptic encephalopathies.

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.

Two Taiwanese siblings with dyschromatosis universalis hereditaria

Two Taiwanese siblings presented with clinical and histological findings of dyschromatosis universalis hereditaria, which is an uncommon hereditary skin disease. A 26-year-old Taiwanese man had developed diffuse hyperpigmentation with hypopigmented spots over his whole body from the age of 4 years. His 34-year-old brother had also developed a similar skin pigmentary defect from about the same age. Histological examination of the hyperpigmented lesions found an increase in melanin in the basal layer, pigmentary incontinence, and some melanophages in the upper dermis but no increase in the number of melanocytes. The unique clinical, histological, and genetic features of this condition are outlined.

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.

A novel missense mutation in DSRAD in a family with dyschromatosis symmetrica hereditaria

Dyschromatosis symmetrica hereditaria (DSH) is a rare autosomal dominant cutaneous disorder characterized by a mixture of hyperpigmented and hypopigmented macules of various sizes on the extremities. Pathogenic mutations in the DSRAD gene have been identified. In this report, we identified a Chinese family with a three-generation pedigree of DSH, in which a novel heterozygous nucleotide G-->A transition was found. It is at position 3,125 in exon 12 of the DSRAD gene which induces a R1042H change in the putative deaminase domain of DSRAD. Our study expands the database on the DSRAD gene mutations in DSH.

Survey and mechanism of skin depigmenting and lightening agents

The type and amount of melanin synthesized by the melanocyte, and its distribution pattern in the surrounding keratinocytes, determines the actual color of the skin. Melanin forms through a series of oxidative reactions involving the amino acid tyrosine in the presence of the enzyme tyrosinase. Tyrosinase catalyses three different reactions in the biosynthetic pathway of melanin in melanocytes: the hydroxylation of tyrosine to l-DOPA and the oxidation of l-DOPA to dopaquinone; furthermore, in humans, dopaquinone is converted by a series of complex reactions to melanin. Among the skin-lightening and depigmenting agents, magnesium-l-ascorbyl-2-phosphate (MAP), hydroxyanisole, N-acetyl-4-S-cysteaminylphenol, arbutin (hydroquinone-beta-d-glucopyranoside) and hydroquinone (HQ) are the most widely prescribed worldwide. However, with reports of potential mutagenicity and epidemics of ochronosis, there has been an increasing impetus to find alternative herbal and pharmaceutical depigmenting agents. A review of the literature reveals that numerous other depigmenting or skin-lightening agents are either in use or in investigational stages. Some of these, such as kojic, glycolic and azelaic acids, are well known to most dermatologists. Others have been discovered and reported in the literature more recently. Several depigmentation and lightening agents are discussed, including their historical background, biochemical characteristics, type of inhibition and activators from various sources. In addition, the clinical importance of mushroom tyrosinase as a recent prospect is discussed in this paper.

Identification of two novel DSRAD mutations in two Chinese families with dyschromatosis symmetrica hereditaria

Dyschromatosis symmetrica hereditaria (DSH) is a hereditary skin disease characterized by the presence of hyperpigmented and hypopigmented macules on face and dorsal aspects of the extremities that appear in infancy or early childhood. Genetic studies have identified mutations in the double-stranded RNA-specific adenosine deaminase (DSRAD) gene, encoding double-stranded RNA-specific adenosine deaminase, to be responsible for this disorder. Here, we report two novel mutations c.2116 G > A (E706K) and c.2848 C > T (Q950X) in the DSRAD gene identified in two Chinese pedigrees with DSH. This study should be useful for genetic counseling and prenatal diagnosis for affected families and in expanding the database on DSRAD gene mutations in DSH.

Familial gigantic melanocytosis

BACKGROUND

Familial gigantic melanocytosis (FGM) is a rare disorder first described in 1984 and termed "familial melanopathy with gigantic melanocytes". The cause of the disorder is still unknown. Melanocytes in both hyper- and hypopigmented skin seem to be unable to deliver melanin to the surrounding keratinocytes.

OBJECTIVE

In this study, we report four new cases of FGM. Electron microscopic examination was performed in a trial to shed more light on the underlying defect in this disorder.

PATIENTS AND METHODS

Patients were examined clinically and biopsies were taken from both hyperpigmented and hypopigmented areas, and divided into two parts; one part was processed for routine microscopic examination with hematoxylin and eosin and Masson Fontana stains. The other portion of the biopsy was fixed in glutraldhyde 3% and processed for electron microscopic (EM) examination.

RESULTS

By light microscopy, the patients' skin showed areas of hyperpigmented basal cells alternating with poorly pigmented areas. Hair follicles in the scalp biopsies showed the same pathology. By EM, pigmented areas showed gigantic melanocytes and heavily pigmented keratinocytes. Nonpigmented areas showed poorly pigmented keratinocytes and fewer, but also gigantic melanocytes.

CONCLUSIONS

The raindrop-like hypopigmentation in this disorder can be explained by a failure of melanocytes to deliver melanin to their surrounding keratinocytes. The cause of the presence of heavily pigmented keratinocytes in the hyperpigmented zones could not be determined. There is a strong possibility of a more widespread abnormality affecting not just the melanocytes.

Identification of a novel mutation in the DSRAD gene in a Chinese pedigree with dyschromatosis symmetrica hereditaria

Dyschromatosis symmetrica hereditaria (DSH) is an autosomal dominant skin disorder characterized by a mixture of hyperpigmented and hypopigmented macules distributed on the face and dorsal aspects of the extremities that appear in infancy or early childhood. The DSH locus has recently been mapped to chromosome 1q21 and then pathogenic mutations have been identified in the DSRAD gene. In the study reported here we examined the DSRAD gene mutations of a three-generation Chinese pedigree with DSH by direct sequencing. We identified a novel heterozygous nucleotide T-->C transition at position 3388 in exon 14 of the DSRAD gene which induces a C1130R change in the putative deaminase domain of DSRAD. Our study expands the database on the DSRAD gene mutations in DSH and enriches the knowledge about the function of the DSRAD gene.

A new arginine substitution mutation of DSRAD gene in a Chinese family with dyschromatosis symmetrica hereditaria

BACKGROUND

Dyschromatosis symmetrica hereditaria (DSH) is a pigmentary genodermatosis of autosomal dominant inheritance characterized by a mixture of hyperpigmented and hypopigmented macules distributed on the dorsal aspects of the hands and feet. To date, only three articles testified that DSH is caused by the mutations of DSRAD gene (also called ADAR1) encoding for RNA-specific adenosine deaminase.

OBJECTIVE

To identify mutations of DSRAD as the disease-causing gene and recognize different mutations giving a clue to insight into the mechanism of DSH.

METHODS

We collected a Chinese DSH family consisting of a total of 11 individuals including five DSH patients (three males and two females). The whole coding region of DSRAD was amplified by polymerase chain reaction and products analyzed by direct sequencing.

RESULTS

We detected a transition, 3463 C>T, leading to a missense mutation (R1155W) in genomic DNAs of five patients, and the point mutation was not found in normal individuals in this DSH family and in 100 unrelated, population-match control individuals.

CONCLUSION

Our data suggests that R1155W missense mutation is a new mutation in exon 15 of DSRAD gene and further testify that DSRAD gene is the pathogenic gene of DSH.

A novel mutation of the DSRAD gene in a Chinese family with dyschromatosis symmetrica hereditaria

Dyschromatosis symmetrica hereditaria (DSH) is a pigmentary genodermatosis of autosomal dominant inheritance characterized by a mixture of hyperpigmented and hypopigmented macules distributed on the dorsal aspects of the hands and feet. It is caused by mutations of the RNA-specific adenosine deaminase gene. We report the identification of a Chinese family with a three-generation pedigree of DSH, in whom a novel tyrosine substitution mutation in DSRAD was demonstrated: a heterozygous nucleotide A-->G transition at position 2879 in exon 10 of the DSRAD gene was detected.

Dyschromatosis universalis hereditaria: Familial case and ultrastructural skin investigation

We report a familial case of dyschromatosis universalis hereditaria (DUH) which is compatible with an autosomal dominant inheritance. The male proband from Bangladesh presented with randomly distributed hyper- and hypo-pigmented skin lesions of variable shape and size with a mottled appearance. Three additional members of the non-consangineous family are similarly affected. Light and electron microscopy show normal numbers of active melanocytes, but different amounts of fully melanized melanosomes in hyper-pigmented and hypo-pigmented macules. Our findings indicate that DUH is not a disorder of number. It appears to be a disorder of melanosome synthesis rate or in addition melanocyte activity.

A gene locus responsible for dyschromatosis symmetrica hereditaria (DSH) maps to chromosome 6q24.2-q25.2

Dyschromatosis symmetrica hereditaria (DSH) is a hereditary skin disease characterized by the presence of hyperpigmented and hypopigmented macules on extremities and face. The gene, or even its chromosomal location, for DSH has not yet been identified. In this study, two Chinese families with DSH were identified and subjected to a genomewide screen for linkage analysis. Two-point linkage analysis for pedigree A (maximum LOD score [Z(max)] = 7.28 at recombination fraction [theta] = 0.00) and pedigree B (Z(max) = 2.41 at theta = 0.00) mapped the locus for DSH in the two families to chromosome 6q. Subsequent multipoint analysis of the two families also provided additional support for the DSH gene being located within the region 6q24.2-q25.2, with Z(max) = 10.64. Haplotype analysis confined the locus within an interval of 10.2 Mbp, flanked by markers D6S1703 and D6S1708. The two families had no identical haplotype within the defined region, which suggests that the two families were different in origin. Further work on identification of the gene for DSH will open new avenues to exploration of the genetics of pigmentation.

Identification of a locus for dyschromatosis symmetrica hereditaria at chromosome 1q11-1q21

Dyschromatosis symmetrica hereditaria is a rare autosomal dominant cutaneous disorder characterized by a mixture of hyperpigmented and hypopigmented macules of various sizes on the face and the dorsal aspects of the extremities. The genetic basis for this disease is unknown. We performed a genome-wide search in two large Chinese families to map the chromosome location of the responsible gene. We identified a locus at chromosome 1q11-1q21 with a cumulative maximum two-point LOD score of 8.85 at marker D1S2343 (at recombination fraction=0.00). Haplotype analyses indicated that the disease gene is located within the 11.6 cM region between markers D1S2696 and D1S2635. This is the first locus identified for dyschromatosis symmetrica hereditaria. This study provides a map location for isolation of a disease gene causing dyschromatosis symmetrica hereditaria.

Dyschromatosis universalis hereditaria: report of a case and review of the literature

We describe dyschromatosis universalis in a 19-month-old Saudi Arabian girl. She had no associated defects and none of the other family members were affected. Similar cases reported from countries other than the Far East, where the disease was first described, are discussed.

Useful applications of DNA repair tests for differential diagnosis of atypical dyschromatosis symmetrica hereditaria from xeroderma pigmentosum

Dyschromatosis symmetrica hereditaria (DSH) is a hereditary skin disease characterized by the presence of pigmented and hypopigmented macules on the extremities and freckles on the face. However, if clinical features are not fully developed in infantile patients, it is difficult to differentiate DSH from xeroderma pigmentosum by clinical features alone. A 2-year-old boy (patient 1), revealed atypical features of DSH with slight susceptibility to sunburn. However, his grandfather (patient 4) who was 67 years old, revealed typical features of DSH, which helped to make an exact diagnosis in patient 1. For patient 2, a 5-year-old boy, and patient 3, a 3-year-old girl, it was more difficult to make a diagnosis because there were no family members with DSH features. DNA repair ability was tested for all four cases by means of unscheduled DNA synthesis and colony formation of skin fibroblasts after ultraviolet light irradiation, which resulted in an accurate diagnosis of DSH. We propose that these tests be performed to make a diagnosis of DSH in the case of poor or atypical clinical symptoms.

Reticulate acropigmentation of Dohi: a case report of autosomal recessive inheritance

Reticulate acropigmentation of Dohi is a rare dyschromic disorder that generally has an autosomal dominant pattern of inheritance. Most of the cases have primarily been described from Japan. Only a few similar cases have been described elsewhere. We describe 3 black siblings, one boy and two girls, who had progressive reticulate hyperpigmented and hypopigmented macules over the dorsa of hands and feet, which began in early childhood. There were no palmar pits or breaks of the epidermal rete ridge pattern nor was there a family history of any pigmentary skin diseases. Three skin biopsies were performed on one patient; a biopsy specimen from a hyperpigmented macule showed increased melanin in all epidermal levels tapering towards the surface, a second biopsy specimen from a hypopigmented macule showed much less melanin, but it had a similar distribution. A third specimen from a hyperpigmented macule for electron microscopy showed a moderate number of stage III and IV melanosomes in the cytoplasm of the melanocytes. To our knowledge, these patients are the first cases reported from the Middle East with an autosomal recessive pattern of inheritance, confirming previous reports.

Dyschromatosis symmetrica hereditaria (reticulate acropigmentation of Dohi): report of a Japanese family with the condition and a literature review of 185 cases

We report a Japanese family with dyschromatosis symmetrica hereditaria (DSH) (MIM 127400 in McKusick's Mendelian Inheritance in Man), a rare autosomal dominant genodermatosis, predominantly occurring among Japanese and Korean individuals. Members of the present family affected with the disease showed a mixture of hyperpigmented and hypopigmented macules distributed on the face and the dorsal aspects of the extremities, which are typical of DSH. As most of the literature on DSH has been written in Japanese, dermatologists outside Japan are not familiar with the condition. In this paper, 185 cases of DSH, most of them reported in Japanese, are reviewed and unique clinical, histological and genetic features of this condition are delineated.