Acrodermatitis continua of Hallopeau and generalised pustular psoriasis: Should they be the same or different entities?

Pustular psoriasis is characterised by eruptions of neutrophilic sterile pustules. The European Rare and Severe Psoriasis Expert Network consensus defines pustular psoriasis into three subtypes; generalised pustular psoriasis (GPP), palmoplantar pustulosis and acrodermatitis continua of Hallopeau (ACH). Mixed forms are categorised according to their predominant features. However, the Japanese Dermatological Association includes ACH under the diagnosis of GPP. This article aims to review the similarities and differences between ACH and GPP. Based on our review, interleukin (IL)-36RN mutations, the most frequent genetic findings in pustular psoriasis are found most commonly in GPP, followed by ACH. Genotypes of IL-36RN mutations among GPP patients and ACH patients are different between European and Asian ethnicities. IL-36 signalling pathway is the main mechanism. Metabolic diseases are common comorbidities and joint involvement can occur in 20.5%-36.4% of both conditions. Associated plaque psoriasis is more common in GPP than in ACH. Generally, ACH, even the generalised type, does not have systemic inflammation whereas GPP can occur with or without systemic inflammation. ACH can occur before, simultaneously, or after the development of GPP. However, response to treatment for GPP and ACH even in the same patients appear to be different. ACH seemed to be more recalcitrant to treatment than GPP but severe flare of GPP can lead to morbidity and mortality. Although GPP and ACH share genotypes and pathogenesis, we believe that ACH should be classified separately from GPP, and not under diagnosis of GPP. Future research is warranted to satisfactorily distinguish the two conditions.

MKLN1 splicing defect in dogs with lethal acrodermatitis

Lethal acrodermatitis (LAD) is a genodermatosis with monogenic autosomal recessive inheritance in Bull Terriers and Miniature Bull Terriers. The LAD phenotype is characterized by poor growth, immune deficiency, and skin lesions, especially at the paws. Utilizing a combination of genome wide association study and haplotype analysis, we mapped the LAD locus to a critical interval of ~1.11 Mb on chromosome 14. Whole genome sequencing of an LAD affected dog revealed a splice region variant in the MKLN1 gene that was not present in 191 control genomes (chr14:5,731,405T>G or MKLN1:c.400+3A>C). This variant showed perfect association in a larger combined Bull Terrier/Miniature Bull Terrier cohort of 46 cases and 294 controls. The variant was absent from 462 genetically diverse control dogs of 62 other dog breeds. RT-PCR analysis of skin RNA from an affected and a control dog demonstrated skipping of exon 4 in the MKLN1 transcripts of the LAD affected dog, which leads to a shift in the MKLN1 reading frame. MKLN1 encodes the widely expressed intracellular protein muskelin 1, for which diverse functions in cell adhesion, morphology, spreading, and intracellular transport processes are discussed. While the pathogenesis of LAD remains unclear, our data facilitate genetic testing of Bull Terriers and Miniature Bull Terriers to prevent the unintentional production of LAD affected dogs. This study may provide a starting point to further clarify the elusive physiological role of muskelin 1 in vivo.

Lethal acrodermatitis (LAD) is an autosomal recessive hereditary disease in dogs. It is characterized by poor growth, immune deficiency and characteristic skin lesions of the paws and of the face. We mapped the LAD locus to a ~1.11 Mb segment on canine chromosome 14. Whole genome sequence data of an LAD affected dog and 191 controls revealed a candidate causative variant in the MKLN1 gene, encoding muskelin 1. The identified variant, a single nucleotide substitution, MKLN1:c.400+3A>C, altered the 5’-splice site at the beginning of intron 4. We experimentally confirmed that this variant leads to complete skipping of exon 4 in the MKLN1 mRNA in skin. Various cellular functions have been postulated for muskelin 1 including roles in intracellular transport processes, cell morphology, cell spreading, and cell adhesion. Our data from dogs reveal a novel in vivo role for muskelin 1 that is related to the immune system and skin. MKLN1 thus represents a novel candidate gene for human patients with unsolved acrodermatitis and/or immune deficiency phenotypes. LAD affected dogs may serve as models to gain more insights into the function of muskelin 1.

Heterogeneity in the genetic alterations and in the clinical presentation of acrodermatitis enteropathic: Case report and review of the literature

Acrodermatitis enteropathic (AE) is a rare autosomal recessive disorder due to a zinc deficiency and characterized by a classical triad of symptoms: dermatitis, alopecia, and diarrhea. The defective gene is SLC39A4, which encodes a zinc transporter. Nevertheless many abnormalities in SLC39A4 have been relieved, only 50% of patients show alterations. Here is reported the case of an infant with mild and incomplete manifestations of AE, for whom the SLC39A4 genetic test was performed. A novel mutation in SLC39A4 was identified. Zinc replacement improved rapidly the skin lesions. Our case highlights the importance of suspecting this rare condition and to perform the genetic test even in those patients who do not fulfil the classical triad of symptoms. Further efforts should be addressed to identify a more strength correlation between genotype and phenotype of this disorder.

Correlation of IL36RN mutation with different clinical features of pustular psoriasis in Chinese patients

Different studies have reported various values for the percentage of patients with IL36RN mutations, and it has also been reported that the sites of these mutations differ among different ethnicities. The current study was a cross-sectional study conducted to investigate the risk factors predicting IL36RN mutation in Chinese patients with different clinical features of pustular psoriasis. 57 Han Chinese patients, including 32 with generalized pustular psoriasis, 14 with palmoplantar pustulosis, 9 with plaque-type psoriasis with pustules, and 2 with erythrodermic psoriasis, were enrolled between March 2013 and July 2014. Blood samples were collected, genomic DNA was extracted from leukocytes, and polymerase chain reaction (PCR)-based Sanger sequencing was used to analyze the coding exons and flanking introns of the IL36RN gene. The patients with generalized pustular psoriasis exhibited the highest IL36RN mutation rate (75 %) among the aforementioned patient types, with the subgroup consisting of those patients who had features of acrodermatitis continua of Hallopeau exhibiting the highest c.115+6T>C mutation rate (93.8 %). In addition, early onset, ever generalized pustular psoriasis (more than two attacks), ever acrodermatitis continua of Hallopeau, inverse psoriasis, and a family history of pustular psoriasis were associated with IL36RN mutation. The c.115+6T>C mutation was the most common and the most important variant in all subtypes of pustular psoriasis with IL36RN mutations among our sample of Chinese patients.

Genetic causes and gene–nutrient interactions in mammalian zinc deficiencies: acrodermatitis enteropathica and transient neonatal zinc deficiency as examples

Discovering genetic causes of zinc deficiency has been a remarkable scientific journey. It started with the description of a rare skin disease, its treatment with various agents, the successful therapy with zinc, and the identification of mutations in a zinc transporter causing the disease. The journey continues with defining the molecular and cellular pathways that lead to the symptoms caused by zinc deficiency. Remarkably, at least two zinc transporters from separate protein families are now known to be involved in the genetics of zinc deficiency. One is ZIP4, which is involved in intestinal zinc uptake. Its mutations can cause acrodermatitis enteropathica (AE) with autosomal recessive inheritance. The other one is ZnT2, the transporter responsible for supplying human milk with zinc. Mutations in this transporter cause transient neonatal zinc deficiency (TNZD) with symptoms similar to AE but with autosomal dominant inheritance. The two diseases can be distinguished in affected infants. AE is fatal if zinc is not supplied to the infant after weaning, whereas TNZD is a genetic defect of the mother limiting the supply of zinc in the milk, and therefore the infant usually will obtain enough zinc once weaned. Although these diseases are relatively rare, the full functional consequences of the numerous mutations in ZIP4 and ZnT2 and their interactions with dietary zinc are not known. In particular, it remains unexplored whether some mutations cause milder disease phenotypes or increase the risk for other diseases if dietary zinc requirements are not met or exceeded. Thus, it is not known whether widespread zinc deficiency in human populations is based primarily on a nutritional deficiency or determined by genetic factors as well. This consideration becomes even more significant with regard to mutations in the other 22 human zinc transporters, where associations with a range of diseases, including diabetes, heart disease, and mental illnesses have been observed. Therefore, clinical tests for genetic disorders of zinc metabolism need to be developed.

SLC39A4 mutation in zinc deficiency patients

OBJECTIVE

To analyze the clinical presentation and SLC39A4 mutations in zinc deficiency patients.

MATERIAL AND METHOD

The authors conducted a cross-sectional study on all cases of zinc deficiency treated at Queen Sirikit National Institute of Child Health between January 2004 and December 2012. Demographic data, clinical manifestations, laboratory results, treatment and outcome were analyzed. Genetic, SLC39A4 for acrodermatitis enteropathic (AE), mutation analysis was performed in all cases.

RESULTS

There were 15 cases, 10 males and 5 females. The age of onset was between 2 and 10 months (median 3 months). Duration of the disease ranged between 3 days and 17 months (median 2 months). Acral and periorificial dermatitis, diarrhea and alopecia were present in 15 cases (100%), 12 cases (80%) and 8 cases (53%) respectively. The characteristic triad of acral and periorificial dermatitis, diarrhea and alopecia was observed in only 6 patients (40%). Serum zinc level ranged between 10 and 111 mcg/dl (mean 49.69 ± 33.87 mcg/100 ml). Low serum zinc level was observed in 10 cases (67%). All of the patients were treated with zinc sulfate 5 mg/kg/day. All cutaneous lesions and diarrhea had resolved within 7 days of starting therapy. A genetic study of SLC39A4 gene in our 15 patients revealed that 3 patients had homozygous c.1878_1879ins21 (p.G627_T633dup) in exonl2. These three patients have to receive lifelong zinc supplementation to prevent recurrence of the disease. The other twelve patients, who did not carry the gene mutation, did not have symptoms after discontinuance of oral zinc therapy. This is the first report of genetically confirmed acrodermatitis enteropathic in Thailand.

CONCLUSION

Acrodermatitis enteropathica is a rare disease, which needs lifelong zinc supplementation. A genetic study of SLC39A4 gene will confirm the diagnosis. Most of patients presenting with characteristic triad of acral and periorificial dermatitis, diarrhea and alopecia in Thailand were acquired zinc deficiency. Early recognition and treatment of the disease will decrease morbidity and mortality.

Extreme population differences in the human zinc transporter ZIP4 (SLC39A4) are explained by positive selection in Sub-Saharan Africa

Extreme differences in allele frequency between West Africans and Eurasians were observed for a leucine-to-valine substitution (Leu372Val) in the human intestinal zinc uptake transporter, ZIP4, yet no further evidence was found for a selective sweep around the ZIP4 gene (SLC39A4). By interrogating allele frequencies in more than 100 diverse human populations and resequencing Neanderthal DNA, we confirmed the ancestral state of this locus and found a strong geographical gradient for the derived allele (Val372), with near fixation in West Africa. In extensive coalescent simulations, we show that the extreme differences in allele frequency, yet absence of a classical sweep signature, can be explained by the effect of a local recombination hotspot, together with directional selection favoring the Val372 allele in Sub-Saharan Africans. The possible functional effect of the Leu372Val substitution, together with two pathological mutations at the same codon (Leu372Pro and Leu372Arg) that cause acrodermatitis enteropathica (a disease phenotype characterized by extreme zinc deficiency), was investigated by transient overexpression of human ZIP4 protein in HeLa cells. Both acrodermatitis mutations cause absence of the ZIP4 transporter cell surface expression and nearly absent zinc uptake, while the Val372 variant displayed significantly reduced surface protein expression, reduced basal levels of intracellular zinc, and reduced zinc uptake in comparison with the Leu372 variant. We speculate that reduced zinc uptake by the ZIP4-derived Val372 isoform may act by starving certain pathogens of zinc, and hence may have been advantageous in Sub-Saharan Africa. Moreover, these functional results may indicate differences in zinc homeostasis among modern human populations with possible relevance for disease risk.

Clioquinol synergistically augments rescue by zinc supplementation in a mouse model of acrodermatitis enteropathica

Background

Zinc deficiency due to poor nutrition or genetic mutations in zinc transporters is a global health problem and approaches to providing effective dietary zinc supplementation while avoiding potential toxic side effects are needed.

Methods/Principal Findings

Conditional knockout of the intestinal zinc transporter Zip4 (Slc39a4) in mice creates a model of the lethal human genetic disease acrodermatitis enteropathica (AE). This knockout leads to acute zinc deficiency resulting in rapid weight loss, disrupted intestine integrity and eventually lethality, and therefore provides a model system in which to examine novel approaches to zinc supplementation. We examined the efficacy of dietary clioquinol (CQ), a well characterized zinc chelator/ionophore, in rescuing the Zip4^{intest KO} phenotype. By 8 days after initiation of the knockout neither dietary CQ nor zinc supplementation in the drinking water was found to be effective at improving this phenotype. In contrast, dietary CQ in conjunction with zinc supplementation was highly effective. Dietary CQ with zinc supplementation rapidly restored intestine stem cell division and differentiation of secretory and the absorptive cells. These changes were accompanied by rapid growth and dramatically increased longevity in the majority of mice, as well as the apparent restoration of the homeostasis of several essential metals in the liver.

Conclusions

These studies suggest that oral CQ (or other 8-hydroxyquinolines) coupled with zinc supplementation could provide a facile approach toward treating zinc deficiency in humans by stimulating stem cell proliferation and differentiation of intestinal epithelial cells.

A mouse model of acrodermatitis enteropathica: loss of intestine zinc transporter ZIP4 (Slc39a4) disrupts the stem cell niche and intestine integrity

Mutations in the human Zip4 gene cause acrodermatitis enteropathica, a rare, pseudo-dominant, lethal genetic disorder. We created a tamoxifen-inducible, enterocyte-specific knockout of this gene in mice which mimics this human disorder. We found that the enterocyte Zip4 gene in mice is essential throughout life, and loss-of-function of this gene rapidly leads to wasting and death unless mice are nursed or provided excess dietary zinc. An initial effect of the knockout was the reprogramming of Paneth cells, which contribute to the intestinal stem cell niche in the crypts. Labile zinc in Paneth cells was lost, followed by diminished Sox9 (sex determining region Y-box 9) and lysozyme expression, and accumulation of mucin, which is normally found in goblet cells. This was accompanied by dysplasia of the intestinal crypts and significantly diminished small intestine cell division, and attenuated mTOR1 activity in villus enterocytes, indicative of increased catabolic metabolism, and diminished protein synthesis. This was followed by disorganization of the absorptive epithelium. Elemental analyses of small intestine, liver, and pancreas from Zip4-intestine knockout mice revealed that total zinc was dramatically and rapidly decreased in these organs whereas iron, manganese, and copper slowly accumulated to high levels in the liver as the disease progressed. These studies strongly suggest that wasting and lethality in acrodermatitis enteropathica patients reflects the loss-of-function of the intestine zinc transporter ZIP4, which leads to abnormal Paneth cell gene expression, disruption of the intestinal stem cell niche, and diminished function of the intestinal mucosa. These changes, in turn, cause a switch from anabolic to catabolic metabolism and altered homeostasis of several essential metals, which, if untreated by excess dietary zinc, leads to dramatic weight loss and death.

Loss-of-function of the zinc transporter ZIP4 in the mouse intestine mimics the lethal human disease acrodermatitis enteropathica. This is a rare disease in humans that is not well understood. Our studies demonstrate the paramount importance of ZIP4 in the intestine in this disease and reveal that a root cause of lethality is disruption of the intestine stem cell niche and impaired function of the small intestine. This, in turn, leads to dramatic weight loss and death unless treated with exogenous zinc.

Congenital zinc deficiency from mutations of the SLC39A4 gene as the genetic background of acrodermatitis enteropathica

Acrodermatitis enteropathica (AE) is an autosomal recessive disorder with the clinical triad of acral dermatitis, diarrhea and alopecia. AE is known to be caused by mutations of the SLC39A4 gene on the chromosome band 8q24.3, encoding the zinc transporter in human. An 8-month-old Korean boy presented with eczematous changes on the inguinal area and knees and was diagnosed with AE. Blood tests revealed a markedly decreased level of plasma zinc, and his symptoms improved on oral zinc replacement. To confirm the diagnosis of AE from congenital zinc deficiency, direct sequencing analysis of SLC39A4 was performed and revealed that he was compound heterozygous for a known missense mutation (Arg95Cys) and a novel splicing mutation in the donor site of intron 7 (c.1287+2T>C). Family study showed that his parents were heterozygous carriers of the mutations. To the best of our knowledge, this is the first report of genetically confirmed AE in Korea.

Hereditary papulotranslucent acrokeratoderma

A 79-year-old woman presented with a history of peeling of the palms and soles that began in young adulthood, with exacerbation after exposure to water. Her mother, 2 sisters, and a female maternal cousin have similar symptoms. Physical examination showed scale and hyperlinearity of the palms. Brief exposure to water initiated the development of 1-to 2-mm, translucent, white papules that were distributed diffusely on the palmar surface, with a concentration at the palmar margins and pressure points. Histopathologic examination showed an acanthotic epidermis with a central depression that was filled with compact orthokeratosis. The physical examination and histopathologic findings are consistent with a diagnosis of hereditary papulotranslucent acrokeratoderma.

Analysis of the liver soluble proteome from bull terriers affected with inherited lethal acrodermatitis

Lethal acrodermatitis (LAD) is a genetic disease affecting bull terrier dogs. The phenotype is similar to that for acrodermatitis enteropathica in humans, but is currently without treatment. The purpose of the research presented here is to determine the biochemical defects associated with LAD using proteomic methodologies. Two affected (male and female) and one unaffected (male) bull terrier pups were euthanized at 14 weeks of age, their livers dissected and prepared for two-dimensional gel electrophoresis (2DE) and densitometry. Approximately 200 protein spots were observed. The density of the spots within each gel was normalized to the total spot volume of the gel; only those soluble liver protein spots that were consistently different in both of the livers of the affected pups compared to the unaffected pup were excised manually and submitted for MALDI mass spectrometry. Thirteen proteins were identified as differentially expressed in the affected, compared to the unaffected, pups. The proteins were involved in numerous cellular physiological functions, including chaperones, calcium binding, and energy metabolism, as well as being associated with the inflammatory response. Of note were haptoglobin, glutamine synthetase, prohibitin and keratin 10 which exhibited at least a fourfold level of differential expression. These data represent the first proteomic analysis of this mutation. The differentially expressed proteins that were identified may be key in understanding the etiology of LAD, and may lead to diagnostic tools for its identification within the bull terrier population.

Acrodermatitis enteropathica

A 13-year-old girl presented with a history of red scaly plaques involving the chest, arms and legs beginning in infancy. Punch biopsy revealed psoriasiform hyperplasia and pallor of the epidermis. The patient's serum zinc level was 36 mug/dl [nl. 66-144 mug/dl]. A diagnosis of acrodermatitis enteropathica was established and the patient responded well to zinc replacement therapy. Acrodermatitis enteropathica is a rare autosomal recessive disorder caused by mutations in SLC39A4, which encodes the tissue-specific zinc transporter ZIP4.

The mouse acrodermatitis enteropathica gene Slc39a4 ( Zip4 ) is essential for early development and heterozygosity causes hypersensitivity to zinc deficiency

The human Zip4 gene (Slc39a4) is mutated in the rare recessive genetic disorder of zinc metabolism acrodermatitis enteropathica, but the physiological functions of Zip4 are not well understood. Herein we demonstrate that homozygous Zip4-knockout mouse embryos die during early morphogenesis and heterozygous offspring are significantly underrepresented. At mid-gestation, an array of developmental defects including exencephalia, anophthalmia and severe growth retardation were noted in heterozygous embryos, and at weaning, many (63/280) heterozygous offspring were hydrocephalic, growth retarded and missing one or both eyes. Maternal dietary zinc deficiency during pregnancy exacerbated these effects, whereas zinc excess ameliorated these effects and protected embryonic development of heterozygotes but failed to rescue homozygous embryos. Heterozygous Zip4 embryos were not underrepresented in litters from wild-type mothers, but were approximately 10 times more likely to develop abnormally than were their wild-type littermates during zinc deficiency. Thus, both embryonic and maternal Zip4 gene expressions are critical for proper zinc homeostasis. These studies suggest that heterozygous mutations in the acrodermatitis gene Zip4 may be associated with a wider range of developmental defects than was previously appreciated, particularly when dietary zinc is limiting.

Acrodermatitis enteropathica and an overview of zinc metabolism

Acrodermatitis enteropathica is a rare autosomal recessive disorder of zinc deficiency. The genetic defect has been mapped to 8q24 and the defective gene identified as SLC39A4, which encodes the zinc transporter Zip4. The diagnosis is made by way of clinical presentation together with histopathology and laboratory tests. Here we provide an overview of zinc metabolism and a description of inherited and acquired zinc deficiency.

A new mutation in exon 3 of the SCL39A4 gene in a Tunisian family with severe acrodermatitis enteropathica

Acrodermatitis enteropathica is a rare autosomal recessive disease that manifests as an inability of the affected individual to absorb intestinal zinc, and therefore patients have nutritional zinc deficiency. Without zinc therapy, this condition is fatal. Mutations in the SLC39A4 gene are responsible for acrodermatitis enteropathica. This gene encodes one member of a human zinc/iron-regulated transporter-like protein, also known as ZIP4, and consists of 12 exons and spans about 4.7 kb. We describe a novel mutation in a Tunisian family in which a chain termination codon in exon 3 yielded a truncated ZIP4 zinc transporter protein.

Acrodermatitis enteropathica (AE) wird durch Mutationen im Zink-Transportergen SLC39A4 verursacht

BACKGROUND

Acrodermatitis enteropathica (AE) is an autosomal recessively inherited disease caused by a decreased intestinal zinc resorption and characterized by severe dermatitis (preferably hands, feet, mouth, genital region), chronic diarrhoea, retardation of growth and development, alopecia and increased proneness to infections. In 2002 it was shown that mutations in the zinc transporter gene SLC39A4 is the cause of AE.

CASE REPORT

Here we report 4 patients with typical clinical signs since early childhood. Under regular substitution with zinc all patients are more or less free of symptoms. The first patient revealed compound-heterozygous missense/nonsense mutations (P200L/ W401X), the three other patients were homozygous for a mutation in intron 1 (c.192 + 19G > A) of the SLC39A4 gene.

CONCLUSION

The diagnosis of hereditary acrodermatitis enteropathica can now easily be confirmed by mutation analysis of the SLC39A4 gene.

Genetic heterogeneity in acrokeratosis verruciformis of Hopf

BACKGROUND

Acrokeratosis verruciformis of Hopf (AKV) is a rare genodermatosis characterized by multiple flat-topped, flesh-coloured papules on the dorsa of hands and feet, and punctuate keratoses on the palms and soles. A mutation in the ATP2A2 gene has been shown to be associated with AKV and with Darier's disease (DD).

OBJECTIVES

To explore the molecular aetiology of AKV and DD.

METHODS

We investigated the clinical and histological information in two families and a sporadic case with AKV and one family and a sporadic case with DD in China. Mutation analysis of ATP2A2 was performed by PCR and direct sequencing, and genotyping and linkage analysis performed using six polymorphic microsatellite markers spanning the locus at 12q23-12q24 containing ATP2A2.

RESULTS

Mutational analysis showed no mutation in ATP2A2 among the AKV patients, but we found two novel mutations (p.C318F and p.M719fs) in the DD patients. The genotyping and linkage analysis results revealed no linkage evidence of the locus at 12q23-12q24 in a large AKV family.

CONCLUSIONS

Our findings provide evidence for the genetic heterogeneity of AKV and demonstrate that mutations in genes other than ATP2A2 are responsible for AKV in a proportion of the Chinese population.

Identification of a unique splice site variant in SLC39A4 in bovine hereditary zinc deficiency, lethal trait A46: An animal model of acrodermatitis enteropathica

Lethal trait A46, also known as bovine hereditary zinc deficiency, Adema disease, and hereditary parakeratosis, is an autosomal recessive disorder first described in 1964, with a clinical presentation similar to that of acrodermatitis enteropathica (AE) in humans. The molecular basis of the defect has not been previously identified. Recently, the basic defect in AE was found to lie in SLC39A4. We report the characterization of the bovine ortholog of SLC39A4 and identification of a unique splice site variant within this gene in affected animals. The mutation leads to exon skipping, leaving the coding region in frame. The gene product is predicted to lack two critical motifs, which lie in adjacent transmembrane domains implicated in the formation of a pore responsible for the transport of zinc. While further functional studies are warranted, this unique variant is likely to be responsible for the impaired zinc absorption in this disease.

Acrodermatitis enteropathica: zinc therapy and possible identification of a carrier state through multiple hair zinc analyses over three decades

We report on the successful use of repeated hair analyses over three decades to monitor zinc and copper status in two siblings with Acrodermatitis enteropathica who were treated with oral zinc sulfate beginning in 1975. Furthermore, we report for the first time that analysis of zinc in hair over a 30-yr period allows for the identification of individuals who might be heterozygous carriers of this autosomal recessive disease and who, therefore, would be expected to have hair zinc levels intermediate between normal, healthy individuals and those with Acrodermatitis enteropathica. Zinc treatment of the two patients with Acrodermatitis enteropathica resulted in remission of the signs and symptoms of the disease within the first month of therapy. However, any short-term interruption (typically, 7-10 d) in oral zinc resulted in an almost immediate relapse, with the reappearance of the skin lesions. We also document the inverse relationship that exists between zinc and copper through analysis of these metals in the scalp hair from the two patients, thus providing a tool for ensuring adequate copper intake in patients taking relatively high doses of zinc over a long period.

Acrodermatite entéropathique chez un nourrisson né à terme nourri exclusivement au sein

BACKGROUND

Acrodermatitis enteropathica is a rare autosomal recessive disorder, caused by impaired absorption of zinc from the gastrointestinal tract. Symptoms of acrodermatitis enteropathica occur within the first few months after birth and tend to appear shortly after discontinuation of breast-feeding. We report a breast-fed infant with acrodermatitis enteropathica.

CASE REPORT

A full term, 4-month-old girl, consulted in dermatologic department for persistent and refractory anogenital lesions since the age of 1 month, with progressive erythematous, vesiculous and squamous lesions, sometimes erosive in a peri orificial and acral pattern. She was calm and healthy baby. She was breast feeding. The diagnosis of acrodermatitis enteropathica was confirmed by decreased plasma zinc level (14 microg/100 ml). Breast milk zinc levels was low (46 microg/100 ml), as plasma zinc level of the mother (94 microg/100 ml). A genetic study showed that she was homozygous for the mutation, whereas her brother and parents were heterozygous. She was given zinc sulphate, and her condition has improved significantly.

DISCUSSION

Acrodermatitis enteropathica is characterized by a characteristic clinical feature and the diagnosis is confirmed by decreased plasma zinc level. Acrodermatitis enteropathica in exclusively breast fed infant is rare, it was essentially reported in premature babies. Our case report is particular because it's concerning a full-term breast-fed infant, with zinc deficiency in breast milk and mother's decreased plasma zinc level.

Gianotti-Crosti syndrome caused by acute hepatitis B virus genotype D infection

A 12-year-old girl with Gianotti-Crosti syndrome caused by hepatitis B virus (HBV) infection was admitted due to eruption on her extremities. Laboratory findings revealed elevation of transaminase, positivity for HB surface antigen (HBsAg), and an IgM type anti-HB core. The eruption and level of transaminase improved, and HBsAg became negative within 2 months of onset. Analysis of the virus revealed it to be genotype D with a genomic length of 3,182 bases and the HBsAg serotype was ayw3, which is very rare in Japan. The possible relationship between Gianotti-Crosti syndrome and HBV genotype D infection is discussed.

Acrodermatitis enteropathica mutations affect transport activity, localization and zinc-responsive trafficking of the mouse ZIP4 zinc transporter

The Zip4 protein is involved in dietary zinc uptake from the intestinal lumen. The human ZIP4 gene (SLC39A4) was identified because of its association with acrodermatitis enteropathica (AE), a genetic disorder of zinc absorption. To date, several SLC39A4 mutations have been identified in AE patients. To investigate the effects of these mutations on function of the Zip4 transporter, we introduced six AE-associated missense mutations into the orthologous mouse ZIP4 gene for functional expression in cultured cells. All mutations decreased 65Zn uptake activity of mZip4, thereby providing a causal link to AE. The mutants fell into two groups based on their phenotypic effects. Several alleles (G340D, L382P, G384R, G643R) failed to localize on the cell surface at high levels. These defects were attributable to misfolding and/or mislocalization in the secretory pathway. Two other alleles (P200L and G539R) accumulated to high levels in the plasma membrane and had wild-type apparent Km values for 65Zn uptake. However, these mutations decreased the Vmax of uptake to approximately 30% of wild-type. We showed previously that wild-type mZip4 is regulated post-translationally in response to zinc status. In zinc-replete cells, mZip4 is found largely in intracellular compartments. In zinc-limited cells, surface levels increase markedly because the rate of endocytosis decreases. Surprisingly, endocytosis of both P200L and G539R is no longer zinc responsive; these proteins are endocytosed at a slow rate regardless of zinc status. These effects suggest a zinc sensing mechanism for regulating Zip4 trafficking in response to zinc.

Mutation spectrum of human SLC39A4 in a panel of patients with acrodermatitis enteropathica

Acrodermatitis enteropathica is rare autosomal recessive disorder characterized by a severe nutritional zinc deficiency. We and others have recently identified the human gene encoding an intestinal zinc transporter of the ZIP family, SLC39A4, as the mutated gene in acrodermatitis enteropathica (AE). A first mutation screening in 8 AE families (15 patients out of 36 individuals) revealed the presence of six different mutations described elsewhere. Based on these results, we have evaluated the involvement of SLC39A4 in 14 patients of 12 additional AE pedigees coming either from France, Tunisia, Austria or Lithuania. A total of 7 SLC39A4 mutations were identified (1 deletion, 2 nonsense, 2 missense, and 2 modifications of splice site), of which 4 are novel: a homozygous nonsense mutation in 3 consanguineous Tunisian families [c.143T>G (p.Leu48X)], a heterozygous nonsense mutation (c.1203G>A (p.Trp401X)) in a compound heterozygote from Austria also exhibiting an already known missense mutation, and distinct homozygous mutations in families from France or Tunisia [c.475-2A>G and c.184T>C (p.Cys62Arg)]. Furthermore, two other potential mutations [c.850G>A (p.Glu284Lys) and c.193-113T>C] were also observed at homozygous state in a French family formerly described. This study brings to 21 the number of reported SLC39A4 mutations in AE families.

Novel SLC39A4 mutations in acrodermatitis enteropathica

Acrodermatitis enteropathica is an autosomal recessive disease characterized by skin involvement due to defective intestinal zinc absorption. Usually, the skin lesions include erythema, erosions, and small blisters in perioral, perianal regions, and hands and feet, which develop soon after weaning from the breast. The acrodermatitis enteropathica gene has been localized to chromosomal region 8q24.3 and subsequently the SLC39A4 gene has been disclosed as the acrodermatitis enteropathica gene. SLC39A4 mutations have been demonstrated in several acrodermatitis enteropathica families, and in this study we have examined two Japanese acrodermatitis enteropathica families for SLC39A4 mutations. The mutation detection strategy consisted of polymerase chain reaction amplification of all 12 exons and flanking intronic sequences, followed by direct nucleotide sequencing. It revealed three novel mutations, 1017ins53, which creates a premature termination codon, and two mis-sense mutations, R95C and Q303H.

Acrodermatitis enteropathica: case report and review of the literature

Acrodermatitis enteropathica (AE) is a rare hereditary disorder caused by impaired absorption of zinc from the gastrointestinal tract. It is characterized by acral and periorificial dermatitis, alopecia, and diarrhea. Symptoms usually begin on weaning from breast or formula feeding. We report a full-term, 21-month-old boy with typical skin lesions and decreased plasma zinc level (12 micro g/dl). The patient was given zinc sulfate 40 mg/day and at the end of 1 month his condition had improved significantly. After reviewing the literature we emphasize the important role of zinc in human metabolism and the difference between AE and acquired zinc deficiencies.

A novel member of a zinc transporter family is defective in acrodermatitis enteropathica

The rare inherited condition acrodermatitis enteropathica (AE) results from a defect in the absorption of dietary zinc. Recently, we used homozygosity mapping in consanguineous Middle Eastern kindreds to localize the AE gene to an approximately 3.5-cM region on 8q24. In this article, we identify a gene, SLC39A4, located in the candidate region and, in patients with AE, document mutations that likely lead to the disease. The gene encodes a histidine-rich protein, which we refer to as "hZIP4," which is a member of a large family of transmembrane proteins, some of which are known to serve as zinc-uptake proteins. We show that Slc39A4 is abundantly expressed in mouse enterocytes and that the protein resides in the apical membrane of these cells. These findings suggest that the hZIP4 transporter is responsible for intestinal absorption of zinc.

Identification of SLC39A4, a gene involved in acrodermatitis enteropathica

We have characterized the human gene SLC39A4, which encodes a protein with features characteristic of a ZIP zinc transporter. The chromosomal location and expression of SLC39A4, together with mutational analysis of eight families affected with acrodermatitis enteropathica, suggest that SLC39A4 is centrally involved in the pathogenesis of this condition.

A novel zinc-regulated human zinc transporter, hZTL1, is localized to the enterocyte apical membrane

Zinc is essential to a wide range of cellular processes; therefore, it is important to elucidate the molecular mechanisms of zinc homeostasis. To date, no zinc transporters expressed at the enterocyte apical membrane, and so essential to mammalian zinc homeostasis, have been discovered. We identified hZTL1 as a human expressed sequence tag with homology to the basolateral enterocyte zinc transporter ZnT1 and deduced the full-length cDNA sequence by PCR. The protein of 523 amino acids belongs to the cation diffusion facilitator family of membrane transporters. Unusually, the predicted topology comprises 12 rather than 6 transmembrane domains. ZTL1 mRNA was detected by reverse transcription-PCR in a range of mouse tissues. A Myc-tagged hZTL1 clone was expressed in transiently transfected polarized human intestinal Caco-2 cells at the apical membrane. Expression of hZTL1 mRNA in Caco-2 cells increased with zinc supplementation of the nutrient medium; however, in the placental cell line JAR hZTL1 appeared not to be regulated by zinc. Heterologous expression of hZTL1 in Xenopus laevis oocytes increased zinc uptake across the plasma membrane. The localization, regulatory properties, and function of hZTL1 indicate a role in regulating the absorption of dietary zinc across the apical enterocyte membrane.

Expression pattern, genomic structure and evaluation of the human SLC30A4 gene as a candidate for acrodermatitis enteropathica

Slc30a4 is the fourth and last identified member of a mammalian proteins family presumably involved in the cellular transport of zinc, solute carrier family 30. The murine homologue of the human SLC30A4 gene has previously been investigated and found responsible for the lm, a phenotype due to zinc deficiency. According to the strong homology between mouse and human SLC30A4 coding sequences, and to the very similar clinical features encountered in the murine lm and in human acrodermatitis enteropathica, SLC30A4 has appeared to us to be a good candidate for acrodermatitis enteropathica. Here we detail the genomic structure of human SLC30A4 together with its localization on chromosome 15q15-q21. We also report the mutational analysis of human SLC30A4 in ten families with acrodermatitis enteropathica, which enabled us to exclude this gene from any involvement in the disorder of the patients examined.

Genomic localization, organization and amplification of the human zinc transporter protein gene, ZNT4, and exclusion as a candidate gene in different clinical variants of acrodermatitis enteropathica

Acrodermatitis enteropathica is an inherited disorder of zinc metabolism, the molecular basis of which is currently unknown. Recent transgenic mouse studies have highlighted the potential significance of certain zinc transport proteins, for example ZnT4, in providing clues to the pathogenesis of zinc-related disorders such as acrodermatitis enteropathica. Specifically, mice of any genotype suckled on ZnT4-deficient mice fail to absorb intestinal zinc and ZnT4-deficient mice also develop dermatitis, alopecia and stunted growth. Therefore, to assess human ZnT4 as a candidate gene/protein in acrodermatitis enteropathica or related disorders, we characterized the intron-exon organization of the human ZNT4 gene, which comprises seven distinct exons spanning approximately 38.7 kb. High-resolution radiation hybrid mapping placed ZNT4 on 15q21.1. We also developed a PCR-based mutation detection strategy using primers placed on flanking introns followed by direct sequencing of the PCR products. Using this approach, we sequenced DNA from five individuals with acrodermatitis enteropathica; no mutations were identified. Thus, ZNT4 is unlikely to be the correct candidate gene for this disorder. We also identified and characterized two common single nucleotide polymorphisms in exon 5 and in the 3' UTR of ZNT4, which will be useful for future genetic linkage studies in assessing ZNT4 as a candidate gene for other inherited disorders of zinc metabolism.

Searching for candidate genes in the new millennium

Completion of the entire sequence of the human genome is having a profound effect on the strategies biological scientists use to identify disease-associated genes. Laborious positional cloning approaches and traditional functional studies are gradually being transformed by emerging genomic and proteomic databases. Some of the exciting challenges investigators now face are the identification of new genes, determining the function of these genes, defining disease associations, and elucidating correlation between genotype and phenotype. To demonstrate how investigative methods for single-gene disorders are changing, we illustrate one possible approach in the search for the gene underlying the autosomal recessive genodermatosis, acrodermatitis enteropathica.

Homozygosity mapping places the acrodermatitis enteropathica gene on chromosomal region 8q24.3

Acrodermatitis enteropathica (AE) is a rare autosomal recessive pediatric disease characterized by dermatitis, diarrhea, alopecia, and growth failure. The disease results from insufficient uptake of zinc by the intestine and can be fatal unless the diet is supplemented with zinc. To map the gene responsible for AE, a genomewide screen was performed on 17 individuals, including 4 affected individuals, in a consanguineous Jordanian family. Three markers-D8S373, D10S212, and D6S1021-had a pattern consistent with tight linkage to a recessive disease: one allele in the affected sibs and multiple alleles in unaffected sibs and parents. Two-point parametric linkage analysis using FASTLINK identified one region, D8S373, with a maximum LOD score >1.5 (1.94 at D8S373: recombination fraction.001). Twelve additional markers flanking D8S373 were used to genotype the extended family, to fine-map the AE gene. All five affected individuals-including one who was not genotyped in the genomewide screen-were found to be homozygous for a common haplotype, spanning approximately 3.5 cM, defined by markers D8S1713 and D8S2334 on chromosomal region 8q24.3. To support these mapping data, seven consanguineous Egyptian families with eight patients with AE were genotyped using these markers, and six patients from five families were found to be homozygous in this region. Multipoint analysis with all consanguineous families, by Mapmaker/Homoz, resulted in a maximum LOD score of 3.89 between D8S1713 and D8S373. Sliding three-point analysis resulted in a maximum LOD score of 5.16 between markers D8S1727 and D8S1744.

Differential expression of cytokine mRNA in skin specimens from patients with erythema migrans or acrodermatitis chronica atrophicans

Erythema migrans, the characteristic skin manifestation of acute Lyme borreliosis, is a self-limited lesion. In contrast, acrodermatitis chronica atrophicans, the typical cutaneous manifestation of late Lyme borreliosis, is a chronic skin condition. In an effort to understand pathogenic factors that lead to different outcomes in dermatoborrelioses, skin biopsy samples from 42 patients with erythema migrans and 27 patients with acrodermatitis chronica atrophicans were analyzed for mRNA expression of five pro-inflammatory cytokines (tumor necrosis factor alpha, interleukin-1 beta, interleukin-6, interferon-gamma, and interleukin-2) and two anti-inflammatory cytokines (interleukin-4 and interleukin-10) by in situ hybridization with cytokine-specific riboprobes. Among the 27 patients who had erythema migrans alone with no associated signs or symptoms, the major cytokines expressed in perivascular infiltrates of T cells and macrophages were the pro-inflammatory cytokine interferon-gamma and the anti-inflammatory cytokine interleukin-10. In the 15 erythema migrans patients who had associated signs and symptoms, including headache, elevated temperature, arthralgias, myalgias, or fatigue, a larger number of macrophages and greater expression of macrophage-derived pro-inflammatory cytokines, tumor necrosis factor alpha, interleukin-1 beta, and interleukin-6, were also found. In comparison, infiltrates of T cells and macrophages in the skin lesions of acrodermatitis chronica atrophicans patients had very little or no interferon-gamma expression. Instead, they usually expressed only the pro-inflammatory cytokine tumor necrosis factor alpha and the anti-inflammatory cytokine interleukin-4. Thus, the activation of pro-inflammatory cytokines in erythema migrans lesions, particularly interferon-gamma, seems to be important in the control of the spirochetal infection. In contrast, the restricted pattern of cytokine expression in acrodermatitis chronica atrophicans, including the lack of interferon-gamma, may be less effective in spirochetal killing, resulting in the chronicity of this skin lesion. J Invest Dermatol 115:1115-1123 2000

[Acrodermatitis enteropathica with mild course]

Acrodermatitis enteropathica is a disorder due to zinc deficiency in a human body. It is disease of autosomal recessive inheritance, that usually occurs in infants, typically develops in early months of life. Classical findings include acrodermatitis, diarrhea and alopecia. Natural course of disease is various from observed ones in 70 tumoral cases to subclinical cases without severe diarrhoea with improvement of post maturation period. We describe a 13-year-old girl with acrodermatitis enteropathica diagnosed after nine years from first symptoms.

Partial characterization of a human zinc-deficiency syndrome by differential display

The effect of the acrodermatitis enteropathica mutation (AE) on gene expression was investigated using differential display. Two differentially expressed cDNAs were partially characterized. The NA8 cDNA (HT11A anchor and HAP 8 random primer pair) was expressed in greater quantity in normal fibroblasts, was 249 bp, and hybridized to three mRNA species (2 kb, 1 kb, 0.8 kb). Northern blot analysis indicated that the relative amounts of the AE mRNA species were reduced by 73%, 75%, and 52%, respectively. The cDNA sequence exhibited 92-93% homology to the human cytochrome oxidase subunit II, as analyzed through the GenBank database. The AEG4 cDNA species (HT11G anchor and HAP 4 random, primer pair) was expressed in greater quantity in AE fibroblasts, was 197 bp, and hybridized to two mRNA species (9 kb, 4 kb). Northern blot analysis indicated that the 9-kb mRNA species was present equally in AE and normal cells, but the 4-kb mRNA species was only present in the AE fibroblasts. The cDNA sequence exhibited 92% homology to LINE1 human retrotransposons, as analyzed through the GenBank database. The functional relationship between the mutation and the reduced expression of cytochrome oxidase subunit II is unknown at this time and needs to be addressed. The increased expression of the LINE1 element in AE fibroblasts may be indicative of an insertion mutation affecting the mRNA of a protein involved in zinc transport, a prospect which requires further investigation.

The acrodermatitis enteropathica mutation affects protein expression in human fibroblasts: analysis by two-dimensional gel electrophoresis

The acrodermatitis enteropathica (AE) mutation affects zinc uptake in human fibroblasts. However, the specific biochemical lesion has not been identified. We have used the technique of two-dimensional gel electrophoresis to identify protein differences in total cell lysate isolated from normal and AE fibroblasts. Two proteins with estimated molecular weights of 49.6 and 49.9 kDa and an isoelectric point of 5.1 were identified in normal fibroblasts but absent from AE fibroblasts. The proteins were purified, subjected to in-gel trypsin digest and the resulting peptides separated by HPLC. Sequences from three peptide fragments (8, 15 and 18 amino acids) were obtained after Edman degradation. None of the fragments exhibited homology to any amino acid sequences in the nonredundant Genbank database. The 15 and 18 amino acid fragments each exhibited 100% homology to a 136 amino acid expressed sequence tag that was homologous (43%) to adipophilin. However, the 15 and 18 amino acid fragments were only 30 and 44% homologous, respectively, to corresponding regions within the expressed sequence tag. Therefore, the 49.6/49.9 kDa protein absent from AE fibroblasts was not related to adipophilin. The 8 amino acid fragment did not exhibit homology to any expressed sequence tag. Therefore, the 49.6/49.9 kDa proteins are novel and may be the cause of the reduced zinc uptake and abnormal zinc metabolism characteristic of fibroblasts carrying the AE mutation.