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Results for “Hypopigmentation”

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PubMed1997

Linear hypopigmentation and hyperpigmentation, including mosaicism.

Linear streaks of hypopigmentation or hyperpigmentation along Blaschko's lines are currently grouped under the names hypomelanosis of Ito (HI) and linear and whorled hypermelanosis (LWH). Recent studies have suggested that these linear pigmentary anomalies reflect underlying genetic mosaicism. Mosaic individuals are composed of two or more genetically distinct cell populations, a normal and an abnormal population. In HI and LWH, the types of genetic defects that are detectable in the abnormal population are highly variable, including tetraploidy, partial or complete trisomies, translocations, and point mutations. These results, together with recent studies indicating the incidence of extracutaneous anomalies is lower in HI but higher in LWH than previously estimated, have important clinical implications. The need for a revised nomenclature as well as possible modifications in current recommendations for patient management are discussed.

Humans↗
PubMed2004

Characterization of melanosomes in murine Hermansky-Pudlak syndrome: mechanisms of hypopigmentation.

The Hermansky-Pudlak syndrome is a genetically heterogeneous autosomal recessive disorder affecting mice and humans, which causes oculocutaneous albinism, prolonged bleeding, and in some cases, pulmonary fibrosis or granulomatous colitis. We previously demonstrated that the gene defects causing murine Hermansky-Pudlak syndrome cause blocks in melanosome biogenesis and/or trafficking in 10 Hermansky-Pudlak syndrome strains. Here, we report an in vivo quantitative analysis on five additional murine models of the Hermansky-Pudlak syndrome. We demonstrate that all strains examined here except for ashen have defects in morphogenesis, the most severely affected is sandy, muted, and buff followed by subtle gray. The ashen strain only has a defect in secretion, as indicated by retention of melanosomes in melanocytes. We document three cellular mechanisms contributing to the hypopigmentation seen in the Hermansky-Pudlak syndrome: (1) exocytosis of immature hypopigmented melanosomes from melanocytes with subsequent keratinocyte uptake; (2) decreased intramelanocyte steady-state numbers of melanosomes available for transfer to keratinocytes; and (3) accumulation of melanosomes within melanocytes due to defective exocytosis, as seen in ashen. We also report that melanosomes in the DBA/2J strain, the parental strain of the Hermansky-Pudlak syndrome strain sandy, are abnormal, indicating that aberrant biogenesis of melanosomes may play a part in the pathogenesis of pigmentary glaucoma observed in these mice.

Animals↗
PubMed2001

Hypopigmentation after non-permanent henna tattoo.

A young girl presented with a hypopigmentation in the shape of the sun. During a holiday in Egypt 3 months before a non-permanent henna tattoo had been applied on her right upper arm. Three to 4 days later there was a severe cutaneous reaction followed by massive swelling of the arm. The lesion took 6 weeks to subside. Patch testing revealed positive reactions to para-phenylenediamine (PPD) but not to henna or any other standard allergen. Especially in Arabic countries PPD is a common additive in natural henna preparations to enhance the weak colouring properties of the natural henna dye. We conclude that henna preparations may contain 'hidden' allergens, such as PPD, which can provoke severe cutaneous reaction without any cosensitization to the henna dye itself.

Child↗
PubMedDate not supplied

Cole disease: hypopigmentation with punctate keratosis of the palms and soles.

Cole disease is an uncommon disorder characterized by distinctive cutaneous hypopigmentation and punctate keratosis of the palms and soles. It is a congenital skin disease with an autosomal dominant inheritance pattern. We report two patients from a family with 15 members, 5 of whom were affected. One of the patients had both types of lesions since birth, while in the other they arose in the first months of life. We studied the pedigree, histopathology, immunohistochemistry, and electron microscopy findings of the hypopigmented macules with the patients' normal skin used as a control. The pedigree showed involvement of both genders, with a Mendelian autosomal dominant inheritance pattern with phenotypic variability in the family. Immunohistochemistry showed a reduction in the melanin pigment in the keratinocytes and normal pigmentation in the melanocytes. Ultrastructural studies showed a strong contrast between the large number of melanosomes in the body and dendrites of the melanocytes, in contrast with the small number of these organelles in the neighboring keratinocytes. These findings suggest that this disease is a primary congenital disorder of the transfer mechanisms of the melanosomes from melanocytes to keratinocytes in hypopigmented lesions, associated with abnormal epidermopoiesis in the punctate hyperkeratosis.

Biopsy, Needle↗
PubMed2001

Hermansky-Pudlak syndrome type 3 in Ashkenazi Jews and other non-Puerto Rican patients with hypopigmentation and platelet storage-pool deficiency.

Hermansky-Pudlak syndrome (HPS), consisting of oculocutaneous albinism and a bleeding diathesis due to the absence of platelet dense granules, displays extensive locus heterogeneity. HPS1 mutations cause HPS-1 disease, and ADTB3A mutations cause HPS-2 disease, which is known to involve abnormal intracellular vesicle formation. A third HPS-causing gene, HPS3, was recently identified on the basis of homozygosity mapping of a genetic isolate of HPS in central Puerto Rico. We now describe the clinical and molecular characteristics of eight patients with HPS-3 who are of non-Puerto Rican heritage. Five are Ashkenazi Jews; three of these are homozygous for a 1303+1G-->A splice-site mutation that causes skipping of exon 5, deleting an RsaI restriction site and decreasing the amounts of mRNA found on northern blotting. The other two are heterozygous for the 1303+1G-->A mutation and for either an 1831+2T-->G or a 2621-2A-->G splicing mutation. Of 235 anonymous Ashkenazi Jewish DNA samples, one was heterozygous for the 1303+1G-->A mutation. One seven-year-old boy of German/Swiss extraction was compound heterozygous for a 2729+1G-->C mutation, causing skipping of exon 14, and resulting in a C1329T missense (R396W), with decreased mRNA production. A 15-year-old Irish/English boy was heterozygous for an 89-bp insertion between exons 16 and 17 resulting from abnormal splicing; his fibroblast HPS3 mRNA is normal in amount but is increased in size. A 12-year-old girl of Puerto Rican and Italian background has the 3,904-bp founder deletion from central Puerto Rico on one allele. All eight patients have mild symptoms of HPS; two Jewish patients had received the diagnosis of ocular, rather than oculocutaneous, albinism. These findings expand the molecular diagnosis of HPS, provide a screening method for a mutation common among Jews, and suggest that other patients with mild hypopigmentation and decreased vision should be examined for HPS.

Adaptor Protein Complex 3↗
PubMed1999

The beta3A subunit gene (Ap3b1) of the AP-3 adaptor complex is altered in the mouse hypopigmentation mutant pearl, a model for Hermansky-Pudlak syndrome and night blindness.

Lysosomes, melanosomes and platelet-dense granules are abnormal in the mouse hypopigmentation mutant pearl. The beta3A subunit of the AP-3 adaptor complex, which likely regulates protein trafficking in the trans - Golgi network/endosomal compartments, was identified as a candidate for the pearl gene by a positional/candidate cloning approach. Mutations, including a large internal tandem duplication and a deletion, were identified in two respective pearl alleles and are predicted to abrogate function of the beta3A protein. Significantly lowered expression of altered beta3A transcripts occurred in kidney of both mutant alleles. The several distinct pearl phenotypes suggest novel functions for the AP-3 complex in mammals. These experiments also suggest mutations in AP-3 subunits as a basis for unique forms of human Hermansky-Pudlak syndrome and congenital night blindness, for which the pearl mouse is an appropriate animal model.

Adaptor Protein Complex beta Subunits↗
PubMed2002

Possible mechanisms of hypopigmentation in lichen sclerosus.

Lichen sclerosus (LS) shares with vitiligo a milky-white appearance. By biopsy, pathognomonic dermal sclerosis readily distinguishes LS from vitiligo and other causes of leukoderma. To determine what the mechanism of hypopigmentation is in LS, we examined samples from LS cases for alterations in melanin content (Fontana-Masson stain) and melanocyte number (HMB-45 [PMEL-17/gp100], Mel-5 [TRP-1], Mart-1 [Melan A]) and compared these findings with those in controls of normal skin, acute scars, vitiligo, and lichen planus (LP; a common inflammatory cause of hyperpigmentation). The degree and extent of melanization found in LS overlapped with that in acute scars showing predominantly hypomelanized keratinocytes, with that in LP containing regions with numerous melanophages, and with that in vitiligo exhibiting focal regions of keratinocytes devoid of melanin pigment. By hematoxylin-eosin staining and immunocytochemistry for Mel-5 and Mart-1, LS had a lower mean count of melanocytes than acute scars, LP, and normal skin per 200 basal keratinocytes. In addition, a few LS cases had a significant loss of melanocytes comparable to that of vitiligo. Surprisingly, Mart-1 identified rare melanocytes in 67% of vitiligo cases and a significantly larger pool of melanocytes in LS and controls other than those labeled by Mel-5. Furthermore, LP and evolving lesions of LS contained the highest Mart-1 counts. HMB-45-immunoreactive melanocytes were found in the majority of acute scars and in LP and late-stage LS lesions at significantly lower levels than Mel-5- and Mart-1- labeled melanocytes, but they were not found in vitiligo or normal skin. We propose that several mechanisms may play a role in the production of leucoderma in LS: 1) decreased melanin production; 2) block in transfer of melanosomes to keratinocytes; and 3) melanocyte loss. The latter finding may be the pathogenic connection (lichenoid dermatitis of LS triggering an autoimmune reaction to melanocytes) that underlies the documented association of LS with vitiligo.

Antigens, Neoplasm↗
PubMed1996

Melanoma-associated hypopigmentation: where are the antibodies?

Antibodies to the B16 melanoma cell line and to tyrosinase have been recently defined in our laboratory in sera of patients with vitiligo, melanoma, melanoma-associated hypopigmentation (MAH), and in healthy subjects. The antibody titers in each subject were measured by enzyme-linked immunosorbent assay, were compared with the mean optical density (OD) of the control group, and were expressed as relative OD. The titers of anti-B16 antibodies (relative OD +/- standard error) were 1.000 (0.058) in the controls, 1.025 (0.077) in patients with metastatic melanoma, 0.5862 (0.15) in MAH, 1.377 in surgery-induced MAH, 1.087 in vaccination with anti-idiotypic antibodies, and 2.098 (0.15) in autoimmune vitiligo. The titers in vitiligo were significantly higher (p < 0.0001) than in MAH or in healthy controls. Antityrosinase antibodies were found in titers of 1.000 (0.1024) in the controls, 1.516 (0.225) in metastatic melanoma, 1.027 (0.180) in MAH, 1.075 in surgery-induced MAH, 2.308 in vaccination-induced MAH, and 4.536 in vitiligo. Differences were found between vitiligo and MAH (p = 0.008), surgery-induced MAH (p = 0.009), vaccination-induced MAH (p = 0.059), and healthy subjects (p < 0.0001). The results of this study point to the cross-antigenicity between melanocytes and melanoma cells, and to participation of antibodies against melanoma-associated membrane antigens in the mechanism leading to the development of MAH in patients with melanoma.

Adult↗
PubMed1993

Advances in inherited disorders of hypopigmentation: comparisons of mice and men.

This review highlights recent advances in the localization of genes responsible for selected inherited disorders of hypopigmentation including Piebaldism, Waardenburg's syndrome, Menkes' disease, as well as oculocutaneous and ocular albinism. Human and mouse homologous sequences, linkage analysis, and cytogenetic studies of affected individuals are powerful tools to identify these loci.

Albinism↗
PubMed1997

Complementation of hypopigmentation in p-mutant (pink-eyed dilution) mouse melanocytes by normal human P cDNA, and defective complementation by OCA2 mutant sequences.

Mutations in the P gene of humans and the homologous p-locus of mice, respectively, result in the homologous disorders oculocutaneous albinism type 2 (OCA2) and pink-eyed dilution. Although clearly required for melanin biosynthesis, the specific function of the P gene product, a melanosomal transmembrane protein expressed in melanocytes of the skin, hair, and eyes, is not yet known. Here we describe lines of immortal melanocytes and melanoblasts from mice of the null genotype p(cp)/p(25H). These p-null melanocytes were severely hypopigmented, although they and the melanoblasts expressed mRNAs for a number of melanosomal proteins. Proliferation of the p-null melanoblasts was normal. Both diploid and immortal p-null melanocytes grew more slowly than wild-type melanocytes, however, and were unusually susceptible to the antibiotic G418; these abnormalities were corrected by culture in high concentrations of L-tyrosine. Transfection of the p-null melanocytes with full-length normal human P cDNA resulted in complementation of deficient melanin biosynthesis and hypopigmentation. In contrast, transfection with mutant human P cDNAs containing amino acid substitutions (A481T, V443I) found in patients with OCA2 resulted in minimal or partial correction, consistent with the corresponding pigmentation phenotypes in patients with these mutations. These results demonstrate the utility of this model system for distinguishing true OCA2 mutations from nonpathologic polymorphisms and for quantitating the effect of these mutations on P function.

Albinism, Oculocutaneous↗
PubMed2006

Sternal malformation/vascular dysplasia syndrome with linear hypopigmentation.

We report a 7-year-old boy who presented with a facial haemangioma, a circumscribed depression over the sternum, coarctation of the aorta, ventricular septal defect and dysplastic cerebral arteries responsible for an episode of acute infarct. This combination of clinical features has been described as the sternal malformation/vascular dysplasia syndrome or PHACES syndrome. At the age of 5 years, lines of hypopigmentation were noted on the right arm, the right hand and the back, along the lines of Blaschko, with no history of any preceding inflammatory changes, and have persisted unchanged. These pigmentary changes have not previously been reported in association with this syndrome.

Abnormalities, Multiple↗
PubMed1997

A new case of oculocerebral hypopigmentation syndrome (Cross syndrome) with additional findings.

Cross syndrome is a rare syndrome characterized by ocular and cutaneous hypopigmentation and neurological manifestations. A few reports have been published since 1967. In this report, we present a new case of Cross syndrome with additional findings such as urinary tract abnormality, bilateral inguinal hernia, focal interventricular septal hypertrophy of the heart and vacuolization of myeloid series cells and distinct ultrastructural features of the skin.

Cardiomegaly↗
PubMed1996

Hypopigmentation in hemodialysis. Acquired hair and skin fairness in a uremic patient undergoing maintenance hemodialysis: case report and review of the literature.

With recent advances in medicine, uremic patients are living longer with an improving quality of life. Several skin diseases have been reported in patients with chronic renal failure, and the opportunity has been offered to elucidate newer cutaneous abnormalities among patients undergoing long-term hemodialysis. Hyperpigmentation was the most prevalent cutaneous abnormality observed in these patients, but hypopigmentation remains an exceptional event. We report here a case of a maintenance hemodialysis patient with an acquired hair and skin fairness. Although the true mechanism involved in this entity remains obscure, it can be correlated with a disturbance of phenylalanine metabolism on the basis of the current knowledge.

Hair↗
PubMed2026

Ampyrone is a direct agonist of human tyrosinase and a potential therapeutic for hypopigmentation disorders.

Significant loss of pigmentation can increase visual disability, skin cancer risk, and psychosocial stress. Tyrosinase (TYR) catalyzes the first and rate-limiting step of melanin synthesis. Inhibitors of TYR are well established and are currently used in clinical settings; however, there is a dearth of direct activators of TYR. Here, using a human TYR construct, we developed high-throughput screening methods, in cell confirmatory assays employing 13C-tyrosine tracing, and computational analysis techniques, and identified ampyrone (4-aminoantipyrine) as a TYR activator. Ampyrone increased the in vitro catalytic activity of the human recombinant intramelanosomal domain of TYR (hTYR) and its hypomorphic variant, Pro406Leu (P406L), a cause of oculocutaneous albinism type 1B (OCA1B). Moreover, ampyrone induced melanin synthesis in both WT and OCA1B human melanocytes, mouse OCA2 melanocytes, as well as 3-dimensional (3D) human skin cultures. Computational studies provided additional insight into the effects of direct TYR agonists on enzyme activity. Our results identify ampyrone as a lead candidate for TYR activation, potentially supporting the development of therapies for patients with genetic and acquired diseases of hypopigmentation.

Humans↗
PubMed2002

[Allergic reactions and hypopigmentation due to temporary tattooing with henna].

Skin tattooing with henna seems a safe alternative to permanent skin tattooing. Contact dermatitis due to henna is rare. Most of the reactions are due to additives, especially paraphenylenediamine, which is added to speed up the process of skin dyeing and to give a darker brown to black colour ('black' henna) instead of the otherwise reddish brown henna colour. Paraphenylenediamine is a well-known strong sensitizer, particularly due to its use as a hair dye. Three patients, two boys aged 8 and 10 years and a 30-year-old woman, developed allergic contact dermatitis after skin painting, after which hypopigmentation remained. Patch tests with paraphenylenediamine were strongly positive in all three patients. This positive reaction means that they will never be able to dye their hair and that they have an increased risk of cross-reactions with other dyes, but also with local anaesthetics, sulfonamides, para-aminoazobenzoic acid or para-aminosalicylic acid.

Adult↗
PubMed1988

Agenesis of the corpus callosum, combined immunodeficiency, bilateral cataract, and hypopigmentation in two brothers.

We describe 2 brothers with a malformation syndrome consisting of agenesis of the corpus callosum, cutaneous hypopigmentation, bilateral cataract, cleft lip and palate, and combined immunodeficiency. The clinical history of both patients was characterized by severe psychomotor retardation, seizures, recurrent severe respiratory infections, and chronic mucocutaneous candidiasis. The children died of bronchopneumonia at age 2 and 3 years, respectively. Immunological investigations showed, in one sib studied, skin anergy to recall antigens, profound depletion of T4+ lymphocytes, and serum IgG2 deficiency. Necropsy showed agenesis of the corpus callosum, hypoplasia of the cerebellar vermis, and profound hypoplasia of the thymus and of the peripheral lymphoid tissue. The distinctive features of these sibs appear to define a previously undescribed hereditary MCA/MR syndrome. The clinical and pathological findings seem to indicate, as a pathogenetic mechanism, a defect involving the embryonic organization of the central nervous system and of the immune system.

Abnormalities, Multiple↗
PubMed1993

Oculocerebral hypopigmentation syndrome associated with Bartter syndrome.

We describe a 20-year-old man with tyrosinase-negative oculocutaneous albinism, mental retardation, epilepsy, sensorineural deafness, ataxia, and Bartter syndrome. When combined, these neurocutaneous and renal findings form a previously unreported combination. The neurological and cutaneous manifestations of this case are distinctly different from those of the syndrome first reported by Cross et al. [1967]. The literature is reviewed and an attempt is made at classifying the oculocerebral hypopigmentation syndromes.

Adult↗
PubMed2000

Direct regulation of the Microphthalmia promoter by Sox10 links Waardenburg-Shah syndrome (WS4)-associated hypopigmentation and deafness to WS2.

The transcription factor Sox10 is genetically linked with Waardenburg syndrome 4 (WS4) in humans and the Dominant megacolon (Dom) mouse model for this disease. The pigmentary defects observed in the Dom mouse and WS4 are reminiscent of those associated with mutations in the microphthalmia (Mitf) gene, which encodes a transcription factor essential for the development of the melanocyte lineage. We demonstrate here that wild type Sox10 directly binds and activates transcription of the MITF promoter, whereas a mutant form of the Sox10 protein genetically linked with WS4 acts as a dominant-negative repressor of MITF expression and can reduce endogenous MITF protein levels. The ability of Sox10 to activate transcription of the MITF promoter implicates Sox10 in the regulation of melanocyte development and provides a molecular basis for the hypopigmentation and deafness associated with WS4.

Animals↗