Genetic linkage of Meleda disease to chromosome 8qter

Treatment of a chronic skin lesion in the lower limb in Meleda disease

Chronic venous skin lesions heal quickly with compression therapy and wound bed preparation. However, there are conditions in which the tissue repair process is more difficult, such as Meleda disease. Meleda disease is a rare genetic pathology, transmitted with an autosomal recessive gene with a prevalence of 1:100 000; it is also called palmoplantar keratoderma. In this pathology, there is a state of chronic inflammation, an alteration of the extracellular matrix and migration of fibroblasts and keratinocytes, which block the proliferative phase of the tissue repair process. Through targeted interventions and the use of bioactive dressings, it is possible to heal the venous ulcer, although this can take a long time. The authors report their experience in relation to a patient with Meleda disease and venous ulceration of seven years.

Mal de Meleda: A Focused Review

Mal de Meleda is a rare autosomal recessive palmoplantar keratoderma (PPK) disease with an estimated prevalence of 1:100,000. Clinically, the onset of the disease is typically soon after birth and features a transgrediens (plantar surface progressing to dorsal surface) and progrediens (worsening with age) pattern of hyperkeratosis of the palms and soles. The disease can feature other potentially disfiguring effects on the hands and feet that can severely impact function. Histologically, the lesions show hyperkeratosis and acanthosis without epidermolysis in the epidermis, accompanied by perivascular lymphocytic infiltrate in the dermis. Secreted LY6/urokinase-type plasminogen activator receptor (uPAR)-related protein-1 (SLURP-1) genetic mutations are implicated in Mal de Meleda. SLURP-1 is involved in mediation of inflammation as well as keratinocyte apoptosis regulation. Because the disease is so rare, there are no set guidelines for management, but the accepted approach tends to include oral acitretin plus topical keratolytic therapy. Genetic counseling should also be offered. This focused review highlights the clinical and histological features, differential diagnoses, genetic background, and the current thoughts on management of Mal de Meleda.

Mal de Meleda: relato de 2 casos de ocorrência familiar

Mal de Meleda é uma ceratodermia palmoplantar transgressiva rara, com prevalência estimada de 1:100.000 habitantes, descrita em 1826 por Stulli, na Ilha de Meleda. A herança autossômica recessiva foi descrita em 1938 e a alteração gênica no lócus 8qter, documentada em 1998. As principais manifestações clínicas decorrem da alteração da ceratinização palmoplantar. Há intensa hiperceratose transgressiva com eritema também no dorso das mãos e pés com distribuição em luvas e botas O aconselhamento genético faz-se necessário, sobretudo nos casos de consanguinidade. Nosso objetivo é relatar 2 casos de ocorrência familiar de pais consanguíneos

Founder effect and estimation of the age of the c.892C>T (p.Arg298Cys) mutation in LMNA associated to Charcot-Marie-Tooth subtype CMT2B1 in families from North Western Africa

CMT2B1, an axonal subtype (MIM 605588) of the Charcot-Marie-Tooth disease, is an autosomal recessive motor and sensory neuropathy characterized by progressive muscular and sensory loss in the distal extremities with chronic distal weakness. The genetic defect associated with the disease is, to date, a unique homozygous missense mutation, p.Arg298Cys (c.892C>T), in the LMNA gene. So far, this mutation has only been found in affected individuals originating from a restricted region of North Western Africa (northwest of Algeria and east of Morocco), strongly suggesting a founder effect. In order to address this hypothesis, genotyping of both STRs and intragenic SNPs was performed at the LMNA locus, at chromosome 1q21.2-q21.3, in 42 individuals affected with CMT2B1 from 25 Algerian families. Our results indicate that the affected individuals share a common ancestral haplotype in a region of about 1.0 Mb (1 cM) and that the most recent common ancestor would have lived about 800-900 years ago (95% confidence interval: 550 to 1300 years).

The role of essential and non-essential elements in Mal de Meleda

Mal de Meleda (MDM) is a rare autosomal recessively inherited palmoplantar keratoderma. In 1826 Stulli described the disease on the Dalmatian island of Meleda. Hyperkeratosis involves other parts of the body such as elbows and knees, in addition to the palms and soles. Zinc deficiency is known to cause hyperkeratozis in addition to other skin changes. We studied the levels of essential and nonessential elements in blood and tissues /nail, hair, skin/ in MDM patients and healthy controls living in Köprüçay area, Turkey. The results show no significant difference in blood zinc, iron, copper, cadmium, and lead levels between MDM patients and healthy controls. The zinc and copper levels of nail and hair in MDM patients did not differ from those of healthy controls.

A novel missense mutation in the gene encoding SLURP-1 in patients with Mal de Meleda from northern Tunisia

BACKGROUND

Mal de Meleda (MDM) is a rare autosomal recessive skin disorder which belongs to the clinically and genetically heterogeneous group of palmoplantar keratodermas (PPK). Clinically, MDM is characterized by erythema and hyperkeratosis of the palms and soles with sharp demarcation that appears soon after birth and progressively extends to the dorsal surface of the hands and feet.

OBJECTIVES

Except for the molecular study reported in Algerian families, MDM has not yet been investigated in the Maghrebian population, characterized by its heterogeneous ethnic background and a high rate of consanguinity. In this study we report genetic and molecular investigations of eight unrelated consanguineous Tunisian families including 17 affected individuals.

METHODS

Eight large consanguineous MDM families who originated from cities of northern Tunisia, with a total of 17 patients and 22 unaffected family members were investigated. Families were genotyped with the following microsatellite markers: CNG003, D8S1751 and D8S1836. Mutation analyses were performed in affected patients, in both parents and in unaffected individuals. Linkage analysis was also performed.

RESULTS

All the clinical features of MDM were constantly present. Nevertheless variable severity was noted among patients. Histological details were recorded. The haplotype analysis of markers CNG003, D8S1751 and D8S1836 revealed that all affected offspring were homozygous by descent for the three polymorphic markers. The maximum lod score value, 3.22, confirmed the evidence for linkage to the ARS gene. Three haplotypes were observed, and the findings suggest that at least three different mutations within the ARS gene segregate with these haplotypes. Three different mutations were identified, the 82delT mutation previously described and two novel missense mutations.

CONCLUSIONS

The results suggest that the ARS gene is likely to be responsible for MDM in the eight Tunisian families. The clinical variability in the expression of PPK in MDM Tunisian patients might be accounted for by the intervention of modifier genes influencing the MDM phenotype.

A novel mutation in the ARS (component B) gene encoding SLURP-1 in a family with Mal de Meleda

Mal de Meleda is a rare, autosomal recessive form of palmoplantar keratoderma. The disease has been mapped to chromosome 8 qter, and recently mutations in the ARS (component B) gene have been identified in families with this disorder. We describe a small family of Turkish origin with Mal de Meleda and identified a novel homozygous mutation, L98P, in ARS (component B). These findings extend the body of evidence implicating mutations in the ARS (component B) gene in Mal de Meleda.

A recurrent mutation in the ARS (component B) gene encoding SLURP-1 in Turkish families with mal de Meleda: evidence of a founder effect

Mal de Meleda is a rare form of palmoplantar keratoderma, and recently mutations in the ARS (component) B gene have been identified in families with this disease. We identified a recurrent nonsense mutation, R96X, in four families of Turkish descent. In this report, we demonstrate that these families share a common ancestral haplotype at the mal de Meleda locus, suggesting a founder effect.

Palmar hyperhidrosis: evidence of genetic transmission

BACKGROUND

Primary palmar hyperhidrosis is a condition marked by excessive perspiration and is reported to have an incidence of 1% in the Western population. It is a potentially disabling disorder that interferes with social, psychological, and professional activities. Over the past several years, several investigators have reported a positive family history in their patients treated for hyperhidrosis. To date, the cause is unknown; furthermore, epidemiologic data are scarce and inadequate.

METHODS

To characterize the genetic contribution to hyperhidrosis, we conducted a prospective study of 58 consecutive patients with palmar, plantar, or axillary hyperhidrosis treated with thoracoscopic sympathectomy from September 1993 to July 1999. Forty-nine of the 58 probands volunteered family history data for these analyses (84% response rate). A standardized questionnaire was administered during the postoperative visit or by phone interview, and a detailed family history was obtained. The same questionnaire was also administered to a set of 20 control patients. The familial aggregation of hyperhidrosis has been quantified by estimating the recurrence risks to the offspring, parents, siblings, aunts, uncles, and cousins of 49 probands and 20 controls. We estimated the penetrance by use of a genetic analysis program.

RESULTS

Thirty-two of 49 (65%) reported a positive family history in our hyperhidrosis group, and 0% reported a positive family history in our control group. A recurrence risk of 0.28 in the offspring of probands compared with frequency of 0.01 in the general population provides strong evidence for vertical transmission of this disorder in pedigrees and is further supported by the 0.14 risk to the parents of the probands. The results indicate that the disease allele is present in about 5% of the population and that one or two copies of the allele will result in hyperhidrosis 25% of the time, whereas the normal allele will result in hyperhidrosis less than 1% of the time.

CONCLUSIONS

We conclude that primary palmar hyperhidrosis is a hereditary disorder, with variable penetrance and no proof of sex-linked transmission. However, this does not exclude other possible causes, and we anticipate that genetic confirmation of this disorder may lead to earlier diagnoses and advances in medical and psychosocial interventions.

KT3.2 and KT3.3, two novel human two-pore K(+) channels closely related to TASK-1

We report the cloning of human KT3.2 and KT3.3 new members of the two-pore K(+) channel (KT) family. Based on amino acid sequence and phylogenetic analysis, KT3.2, KT3.3, and TASK-1 constitute a subfamily within the KT channel mammalian family. When Xenopus oocytes were injected with KT3.2 cRNA, the resting membrane potential was brought close to the potassium equilibrium potential. At low extracellular K(+) concentrations, two-electrode voltage-clamp recordings revealed the expression of predominantly outward currents. With high extracellular K(+) (98 mM), the current-voltage relationship exhibited weak outward rectification. Measurement of reversal potentials at different [K(+)](o) revealed a slope of 48 mV per 10-fold change in K(+) concentration as expected for a K(+)-selective channel. Unlike TASK-1, which is highly sensitive to changes of pH in the physiological range, KT3.2 currents were relatively insensitive to changes in intracellular or extracellular pH within this range due to a shift in the pH dependency of KT3.2 of 1 pH unit in the acidic direction. On the other hand, the phorbol ester phorbol 12-myristate 13-acetate (PMA), which does not affect TASK-1, produces strong inhibition of KT3.2 currents. Human KT3.2 mRNA expression was most prevalent in the cerebellum. In rat, KT3.2 is exclusively expressed in the brain, but it has a wide distribution within this organ. High levels of expression were found in the cerebellum, medulla, and thalamic nuclei. The hippocampus has a nonhomogeneous distribution, expressing at highest levels in the lateral posterior and inferior portions. Medium expression levels were found in neocortex. The KT3.2 gene is located at chromosome 8q24 1-3, and the KT3.3 gene maps to chromosome 20q13.1.

Homozygosity at chromosome 8qter in individuals affected by mal de Meleda (Meleda disease) originating from the island of Meleda

BACKGROUND

The inherited palmoplantar keratodermas (PPKs) are a clinically heterogeneous group of disorders characterized by thickening of the skin of the palms and the soles. These diseases also exhibit genetic heterogeneity and many autosomal dominant and recessive forms have been described. Mal de Meleda (Meleda disease, MD) is an autosomal recessive form of PPK first described on the Dalmatian island of Meleda. A gene for MD has recently been assigned to the most telomeric portion of chromosome 8q using two large Algerian families.

OBJECTIVES

To determine whether the same gene underlies the skin disease in Meleda islanders.

METHODS

We have examined five affected individuals originating from the Dalmatian island itself for 8qter homozygosity.

RESULTS

This region was found to be homozygous in all five affected individuals but in none of the 20 other unaffected family members examined.

CONCLUSIONS

The current study confirms the localization of a gene for MD to 8qter using samples from the island of Meleda, highlighting the clinical and genetic homogeneity of this condition.