Functional characterization of variants in human ABCC11, an axillary osmidrosis risk factor.

Human ATP-binding cassette transporter C11 (ABCC11) is a membrane protein exhibiting ATP-dependent transport activity for a variety of lipophilic anions including endogenous substances and xenobiotics such as anti-cancer agents. Accumulating evidence indicates that ABCC11 wild type is responsible for the high-secretion phenotypes in human apocrine glands including wet type of earwax and the risk of axillary osmidrosis. Also, a less-functional variant of ABCC11 was reportedly associated with a risk for drug-induced toxicity in humans. Thus, functional change in ABCC11 may affect individual's constitution and drug toxicity, which led us to reason that functional validation of genetic variations in ABCC11 should be of importance. Therefore, in addition to p.G180R (a well-characterized non-functional variant of ABCC11), we studied cellular expression and function of 10 variants of ABCC11. In this study, ABCC11 function was evaluated as an ATP-dependent transport of radio labeled-dehydroepiandrosterone sulfate using ABCC11-expressing plasma membrane vesicles. Except for p.G180R, other 10 variants were maturated as an N-linked glycoprotein and expressed on the plasma membrane. We found that six variants impaired the net cellular function of ABCC11. Among them, p.R630W was most influential. Including this identification of a significantly-dysfunctional variant, our findings will extend our understanding of genetic variations and biochemical features of ABCC11 protein.

Soy Isoflavone Genistein Inhibits an Axillary Osmidrosis Risk Factor ABCC11: In Vitro Screening and Fractional Approach for ABCC11-Inhibitory Activities in Plant Extracts and Dietary Flavonoids.

Axillary osmidrosis (AO) is a common chronic skin condition characterized by unpleasant body odors emanating from the armpits, and its aetiology is not fully understood. AO can seriously impair the psychosocial well-being of the affected individuals; however, no causal therapy has been established for it other than surgical treatment. Recent studies have revealed that human ATP-binding cassette transporter C11 (ABCC11) is an AO risk factor when it is expressed in the axillary apocrine glands-the sources of the offensive odors. Hence, identifying safe ways to inhibit ABCC11 may offer a breakthrough in treating AO. We herein screened for ABCC11-inhibitory activities in 34 natural products derived from plants cultivated for human consumption using an in vitro assay system to measure the ABCC11-mediated transport of radiolabeled dehydroepiandrosterone sulfate (DHEA-S-an ABCC11 substrate). The water extract of soybean (Glycine max) was found to exhibit the strongest transport inhibition. From this extract, via a fractionation approach, we successfully isolated and identified genistein, a soy isoflavone, as a novel ABCC11 inhibitor with a half-maximal inhibitory concentration value of 61.5 µM. Furthermore, we examined the effects of other dietary flavonoids on the ABCC11-mediated DHEA-S transport to uncover the effects of these phytochemicals on ABCC11 function. While further human studies are needed, our findings here about the natural compounds will help develop a non-surgical therapy for AO.

A missense variant of the ABCC11 gene is associated with Axillary Osmidrosis susceptibility and clinical phenotypes in the Chinese Han Population.

Axillary osmidrosis (AO) is a common condition characterized by an offensive odor arising from apocrine gland secretions in the axillae that socially and psychologically impairs affected individuals. The exact aetiology of AO is still not fully understood, but genetic factors have been suggested to play an important role. Recently, a single nucleotide polymorphism (SNP) rs17822931 in the ABCC11 gene located on human chromosome 16q12.1 has been shown to be associated with AO. In this study, we genotyped rs17822931 in two independent samples of Chinese Hans including 93 AO individuals vs 95 controls and 81 AO individuals vs 106 controls by using SNaPshot Multiplex Kit. We confirmed the association for ABCC11 gene, showing that rs17822931-G was significantly associated with increased risk for AO (Pcombined = 1.42E-21, OR = 83.94, 95% CI = 83.03-84.85). We also found rs17822931 was associated with subphenotypes of AO. AO individuals carrying the risk allele G are more likely to show wet earwax (P = 2.40E-05), higher frequency of family history (P = 1.04E-02) and early age of onset (P = 3.81E-02). Our study concluded that the association of rs17822931 in the ABCC11 gene with AO was replicated in Chinese Han population.

Clinical and Molecular Evidence of ABCC11 Protein Expression in Axillary Apocrine Glands of Patients with Axillary Osmidrosis.

Accumulating evidence suggests that the risk of axillary osmidrosis is governed by a non-synonymous single nucleotide polymorphism (SNP) 538G>A in human ATP-binding cassette C11 (ABCC11) gene. However, little data are available for the expression of ABCC11 protein in human axillary apocrine glands that produce apocrine sweat-a source of odor from the armpits. To determine the effect of the non-synonymous SNP ABCC11 538G>A (G180R) on the ABCC11 in vivo, we generated transiently ABCC11-expressing transgenic mice with adenovirus vector, and examined the protein levels of each ABCC11 in the mice with immunoblotting using an anti-ABCC11 antibody we have generated in the present study. Furthermore, we examined the expression of ABCC11 protein in human axillary apocrine glands extracted from axillary osmidrosis patients carrying each ABCC11 genotype: 538GG, GA, and AA. Analyses of transiently ABCC11-expressing transgenic mice showed that ABCC11 538G>A diminishes the ABCC11 protein levels in vivo. Consistently, ABCC11 protein was detected in the human axillary apocrine glands of the 538GG homozygote or 538GA heterozygote, not in the 538AA homozygote. These findings would contribute to a better understanding of the molecular basis of axillary osmidrosis.

Genetic Disorders with Dyshidrosis: Ectodermal Dysplasia, Incontinentia Pigmenti, Fabry Disease, and Congenital Insensitivity to Pain with Anhidrosis.

Sweating is regulated by various neurohormonal mechanisms. A disorder in any part of the sweating regulatory pathways, such as the thermal center, neurotransmitters in the central to peripheral nerve, innervation of periglandular neurotransmission, and sweat secretion in the sweat gland itself, induces dyshidrosis. Therefore, hereditary disorders with dyshidrosis result from a variety of causes. These diseases have characteristic symptoms derived from each pathogenesis besides dyshidrosis. The information in this chapter is useful for the differential diagnosis of representative genetic disorders with dyshidrosis.

Diagnosis of Human Axillary Osmidrosis by Genotyping of the Human ABCC11 Gene: Clinical Practice and Basic Scientific Evidence.

The importance of personalized medicine and healthcare is becoming increasingly recognized. Genetic polymorphisms associated with potential risks of various human genetic diseases as well as drug-induced adverse reactions have recently been well studied, and their underlying molecular mechanisms are being uncovered by functional genomics as well as genome-wide association studies. Knowledge of certain genetic polymorphisms is clinically important for our understanding of interindividual differences in drug response and/or disease risk. As such evidence accumulates, new clinical applications and practices are needed. In this context, the development of new technologies for simple, fast, accurate, and cost-effective genotyping is imperative. Here, we describe a simple isothermal genotyping method capable of detecting single nucleotide polymorphisms (SNPs) in the human ATP-binding cassette (ABC) transporter ABCC11 gene and its application to the clinical diagnosis of axillary osmidrosis. We have recently reported that axillary osmidrosis is linked with one SNP 538G>A in the ABCC11 gene. Our molecular biological and biochemical studies have revealed that this SNP greatly affects the protein expression level and the function of ABCC11. In this review, we highlight the clinical relevance and importance of this diagnostic strategy in axillary osmidrosis therapy.

Coloured sweat in two brothers: First report of familial chromhidrosis.

The uncommon diagnosis of chromhidrosis is most frequently made in young adults. This sweat gland disease, although benign, may impact significantly on the patient's quality of life. We describe the first report of familial chromhidrosis of pseudo-eccrine type (pseudochromhidrosis) occurring in two brothers aged 9 and 12 years. The classification and causality of chromhidrosis is described and approaches to assessment and management are outlined.

Association between the ABCC11 gene polymorphism and the expression of apolipoprotein D by the apocrine glands in axillary osmidrosis.

It has been suggested that the adenosine triphosphate­binding cassette sub­family C member 11 (ABCC11) gene polymorphism and apolipoprotein D (ApoD), an odor precursor carrier, may be important in the formation of axillary odor. To date, few studies have examined the potential correlation between these two factors. The present study aimed to investigate the association between a 538 G>A single­nucleotide polymorphism (SNP) of the ABCC11 gene and the mRNA expression levels of ApoD in the apocrine gland of patients with osmidrosis. The 538 G>A polymorphism genotypes of 33 patients with a clinical diagnosis of osmidrosis were analyzed by polymerase chain reaction (PCR) and a base­quenched probe method, and they were divided into two groups according to the results. The G allele functions as a dominant gene; therefore, patients with the GG or GA genotype were allocated to Group I (n=28) and patients with the AA genotype to Group II (n=5). The mRNA expression levels of ApoD in the apocrine glands were determined by reverse transcription­PCR. The results indicated that the mRNA expression levels of ApoD were significantly higher in the apocrine glands of patients in Group I compared with those in Group II (P<0.01). In conclusion, the results indicated that the ABCC11 gene SNP of the 538 G>A allele was associated with a downregulation of the mRNA expression of ApoD in the apocrine glands, which may indicate a role for the ABCC11 gene in the mediation of osmidrosis by enhancing the transition of odor precursors via the ApoD pathway.

[Correlation between ABCC11 gene single nucleotide polymorphism and the incidence of axillary osmidrosis in Chinese Han population].

OBJECTIVE: To explore the relationship between ABCC11 gene single nucleotide polymorphism (SNP) and the incidence of axillary osmidrosis in Chinese Han population. METHODS: The genotype of ABCC11 gene SNP at rs17822931 in 40 patients with axillary osmidrosis and 5 normal Han people was detected and analyzed by high resolution melt and gene sequencing. RESULTS: The detection of the genotype of ABCC11 gene SNP at rs17822931 showed that: 37 of the 40 patients were GA genotype and the other 3 were GG genotype, while the 5 normal subjects were AA genotype. CONCLUSION: SNP in ABCC11 is the genetic cause of axillary osmidrosis. GG or GA leads to axillary osmidrosis, while AA allele presents the absence of axillary osmidrosis.

Correlation of axillary osmidrosis to a SNP in the ABCC11 gene determined by the Smart Amplification Process (SmartAmp) method.

Axillary osmidrosis (AO) is caused by apocrine glands secretions that are converted to odouriferous compounds by bacteria. A potential link between AO and wet earwax type has been implicated by phenotype-based analysis. Recently, a non-synonymous single nucleotide polymorphism (SNP) 538G> A (Gly180Arg) in the human adenosine triphosphate (ATP)-binding cassette (ABC) transporter ABCC11 gene was found to determine the type of earwax. In this context, we examined a relationship between the degree of AO and the ABCC11 genotype. We have genotyped the SNP 538G> A in a total of 82 Japanese individuals (68 volunteers and 14 AO patients) by both DNA sequencing and the recently developed Smart Amplification Process (SmartAmp). The degree of AO in Japanese subjects was associated with the genotype of the ABCC11 gene as well as wet earwax type. In most AO patients investigated in this study, the G/G and G/A genotypes well correlated with the degree of AO, whereas A/A did not. The specific SmartAmp assays developed for this study provided genotypes within 30 min directly from blood samples. In East Asian countries, AO is rather infrequent. Although the judgement of the degree of AO prevalence is subjective, the SNP 538G> A in ABCC11 is a good genetic biomarker for screening for AO. The SmartAmp method-based genotyping of the ABCC11 gene would provide an accurate and practical tool for guidance of appropriate treatment and psychological management for patients.

A strong association of axillary osmidrosis with the wet earwax type determined by genotyping of the ABCC11 gene.

BACKGROUND: Two types of cerumen occur in humans: the wet type with brownish, sticky earwax, and the dry type with a lack of or reduced ceruminous secretion. The wet type is common in populations of European and African origin, while the dry type is frequently seen in Eastern Asian populations. An association between axillary odor and the wet-type earwax was first identified approximately 70 years ago. The data were based on a phenotypical analysis of the two phenotypes among the Japanese by a researcher or by self-declaration of the subjects examined, and were not obtained using definite diagnostic methods. Recently, we identified a single-nucleotide polymorphism (SNP; rs17822931) of the ABCC11 gene as the determinant of the earwax types. In the present study, to determine whether the SNP can serve as a diagnostic marker for axillary osmidrosis (AO), we examined genotypes at rs17822931 in 79 Japanese AO individuals. AO was defined here as a clinical condition of individuals with a deep anxiety regarding axillary odor and had undergone the removal of bilateral axillary apocrine glands. RESULTS: A comparison of the frequencies of genotypes at rs17822931 in the 79 AO individuals and in 161 Japanese from the general population showed that AO was strongly associated with the wet earwax genotype. A total of 78 (98.7%) of 79 AO patients had either the GG or GA genotype, while these genotypes were observed in 35.4% (57/161) of the subjects from the general population (p < 1.1 x 10(-24), by Fisher's exact test). CONCLUSION: The strong association between the wet-earwax associated ABCC11-genotypes (GG and GA) and AO identified in this study indicates that the genotypes are good markers for the diagnosis of AO. In addition, these results suggest that having the allele G is a prerequisite for the axillary odor expression. In other words, the ABCC11 protein may play a role in the excretory function of the axillary apocrine gland. Together, these results suggest that when an AO individual visiting a hospital is diagnosed with dry-type earwax by ABCC11-genotyping, surgical removal of their axillary glands may not be indicated.

Earwax, osmidrosis, and breast cancer: why does one SNP (538G>A) in the human ABC transporter ABCC11 gene determine earwax type?

One single-nucleotide polymorphism (SNP), 538G>A (Gly180Arg), in the ABCC11 gene determines the type of earwax. The G/G and G/A genotypes correspond to the wet type of earwax, whereas A/A corresponds to the dry type. Wide ethnic differences exist in the frequencies of those alleles, reflecting global migratory waves of the ancestors of humankind. We herein provide the evidence that this genetic polymorphism has an effect on the N-linked glycosylation of ABCC11, intracellular sorting, and proteasomal degradation of the variant protein. Immunohistochemical studies with cerumen gland-containing tissue specimens revealed that the ABCC11 WT protein was localized in intracellular granules and large vacuoles, as well as at the luminal membrane of secretory cells in the cerumen gland, whereas granular or vacuolar localization was not detected for the SNP (Arg180) variant. This SNP variant lacking N-linked glycosylation is recognized as a misfolded protein in the endoplasmic reticulum and readily undergoes ubiquitination and proteasomal degradation, which determines the dry type of earwax as a mendelian trait with a recessive phenotype. For rapid genetic diagnosis of axillary osmidrosis and potential risk of breast cancer, we developed specific primers for the SmartAmp method that enabled us to clinically genotype the ABCC11 gene within 30 min.

Transient correction of the basic defect in sweat glands in an individual with cystic fibrosis carrying the complex CFTR allele F508del-R553Q.

The molecular pathology of mutant F508del CFTR is partially corrected in vitro by the secondary amino acid substitution R553Q in the ABC signature motif. An individual with the CFTR genotype R553X/F508del-R553Q showed the typical symptoms and electrophysiological anomalies of cystic fibrosis in the airways and intestine. Sweat chloride concentrations were normal early in life, but were later raised into the range that is diagnostic for cystic fibrosis, suggesting that R553Q could temporarily correct the basic defect in sweat glands. R553Q caused a delay in diagnosis because of false negative sweat tests but was not a disease reverting suppressor mutation as had been inferred from cellular models.

Cold-induced sweating syndrome: a report of two cases and demonstration of genetic heterogeneity.

OBJECTIVES: To characterize the specific autonomic disturbances underlying the cold-induced sweating syndrome (CISS), and to describe a novel genetic variant of this rare recessive disorder. The two not previously reported patients had similar dysmorphic features: abnormal facial appearance, high arched palate, low set rotated ears, flexion deformities of elbows and fingers and scoliosis. Most noticeable were their paradoxical sweat responses: cold ambient temperature induced a profuse sweating over the face, arms and trunk but not over the lower limbs; while in the heat very little sweating occurred primarily on the legs. Testing of autonomic functions demonstrated normal cardiovascular reflexes and postganglionic sympathetic efferent functions. Sural nerve morphology and number of unmyelinated fibers was normal and skin biopsies showed normal appearing eccrine sweat glands. MRI scans revealed no structural brain abnormalities. Oral clonidine, prescribed in one patient, completely suppressed cold-induced sweating. Observed clinical features matched those of two sisters reported from Israel and of two brothers reported from Norway. All six cases presented a similar phenotype. The Norwegian, Israeli and Canadian cases were homozygous or compound heterozygous, respectively, for mutations in the CRLF1 gene on chromosome 19p12 (CISS1). The Australian case, however, had no pathogenic sequence variants in the CRLF1 gene, but was compound heterozygous for mutations in the CLCF1 gene on chromosome 11q13.3 (CISS2). CONCLUSION: The rare cold-induced sweating syndrome is genetically heterogeneous and is probably caused by central and peripheral impairment of sudomotor functions. This is the first detailed report on the clinical consequences of mutations in the CLCF1 gene in humans. Directions for medical therapies are outlined to achieve long term symptom control.

Towards a new classification of ectodermal dysplasias.

Ectodermal dysplasias (EDs) constitute a large and complex group of diseases characterized by various defects in hair, nails, teeth and sweat glands. Of the 170 EDs described so far, fewer than 30 have been explained at the molecular level with identification of the causative gene. This review proposes a new classification of EDs based on the function of the protein encoded by the mutated gene. The EDs are reviewed in light of the recent molecular and biochemical findings and an attempt is made to classify ED causative genes into four major functional subgroups: cell-cell communication and signalling; adhesion; transcription regulation; and development.

Genotype and phenotype in cystic fibrosis.

Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene which encodes a protein expressed in the apical membrane of exocrine epithelial cells. CFTR functions principally as a cAMP-induced chloride channel and appears capable of regulating other ion channels. Besides the most common mutation, DeltaF508, accounting for about 70% of CF chromosomes worldwide, more than 850 mutant alleles have been reported to the CF Genetic Analysis Consortium. These mutations affect CFTR through a variety of molecular mechanisms which can produce little or no functional CFTR at the apical membrane. This genotypic variation provides a rationale for phenotypic effects of the specific mutations. The extent to which various CFTR alleles contribute to clinical variation in CF is evaluated by genotype-phenotype studies. These demonstrated that the degree of correlation between CFTR genotype and CF phenotype varies between its clinical components and is highest for the pancreatic status and lowest for pulmonary disease. The poor correlation between CFTR genotype and severity of lung disease strongly suggests an influence of environmental and secondary genetic factors (CF modifiers). Several candidate genes related to innate and adaptive immune response have been implicated as pulmonary CF modifiers. In addition, the presence of a genetic CF modifier for meconium ileus has been demonstrated on human chromosome 19q13.2. The phenotypic spectrum associated with mutations in the CFTR gene extends beyond the classically defined CF. Besides patients with atypical CF, there are large numbers of so-called monosymptomatic diseases such as various forms of obstructive azoospermia, idiopathic pancreatitis or disseminated bronchiectasis associated with CFTR mutations uncharacteristic for CF. The composition, frequency and type of CFTR mutations/variants parallel the spectrum of CFTR-associated phenotypes, from classic CF to mild monosymptomatic presentations. Expansion of the spectrum of disease associated with the CFTR mutant genes creates a need for revision of the diagnostic criteria for CF and a dilemma for setting nosologic boundaries between CF and other diseases with CFTR etiology.

Scarcity of mutations detected in families with X linked hypohidrotic ectodermal dysplasia: diagnostic implications.

Indirect molecular diagnosis of X linked hypohidrotic ectodermal dysplasia (XLHED), a congenital disorder of hair, teeth, and eccrine sweat glands, has been possible by linkage analysis. Direct mutation detection would enable carrier detection in female relatives of sporadic cases, as well as help distinguish XLHED from the rarer, clinically indistinguishable, autosomal recessive disorder ARHED. Recently, a candidate gene for XLHED has been identified. Genomic DNA from 162 affected males and 21 females, who were either obligate carriers or had manifestations of the disorder, were screened by SSCP analysis. A subset of the patients had been previously screened for large genomic deletions and had limited screening of a single exon by SSCP analysis. The two known exons were amplified using flanking primers. Approximately 7% of patients, all males, had putative mutations identified within exon 1, but no variants were found within exon 2. Ten different putative mutations and four probable polymorphisms were identified. Both of the known exons were sequenced in 10 patients who had no detectable SSCP changes, but no additional mutations were found. No correlation between phenotype and genotype was evident between either affected subjects or subjects with or without detectable mutations. The results of the study indicate that only a small minority of affected males can be diagnosed by direct mutation analysis, and that the remainder of the patients are likely to have mutations in as yet unidentified exons of the EDA gene. Linkage analysis, in informative situations, therefore remains the only practical diagnostic option available.

A functioning eccrine hamartoma associated with Down's syndrome (46, xx,-21,+t(21q21q).

Pure eccrine hamartomas are very rare, and commonly present as localized areas of hyperhidrosis in normal looking skin. We describe a case of bilateral functioning eccrine hamartomas with macroscopically abnormal features in association with Down's syndrome.