We describe here eleven different mutations in SPINK5, encoding the serine protease inhibitor LEKTI, in 13 families with Netherton syndrome (NS, MIM256500). Most of these mutations predict premature termination codons. These results disclose a critical role of SPINK5 in epidermal barrier function and immunity, and suggest a new pathway for high serum IgE levels and atopic manifestations.

Pseudoxanthoma elasticum (PXE) is a heritable connective tissue disorder caused by mutations in an ABC (ATP-Binding Cassette) transporter gene (ABCC6), which manifests with cutaneous, ophthalmologic, and cardiovascular findings. We studied a cohort of 19 families with PXE, and identified 16 different mutations, nine of which were novel variants. The mutation detection rate was about 77%. We found that arginine codon 518 was, with the previously described R1141X and EX23_29del, a recurrently mutated amino acid (11.5% of the mutations detected for each variant R518Q and R518X). No clear delineation of genotype/phenotype correlation was identified, and marked intra-familial variability of the disease was seen in one family. One family with pseudodominant inheritance displayed three distinct ABCC6 mutations, providing further evidence for the probable exclusive recessive transmission of PXE. These data contribute to the expanding database of ABCC6 mutations, to the description of phenotypic variability, and inheritance in PXE, and should be helpful for genetic counselling.

Netherton syndrome (NS [MIM 256500]) is a rare and severe autosomal recessive disorder characterized by congenital ichthyosis, a specific hair-shaft defect (trichorrhexis invaginata), and atopic manifestations. Infants with this syndrome often fail to thrive; life-threatening complications result in high postnatal mortality. We report the assignment of the NS gene to chromosome 5q32, by linkage analysis and homozygosity mapping in 20 families affected with NS. Significant evidence for linkage (maximum multipoint LOD score 10.11) between markers D5S2017 and D5S413 was obtained, with no evidence for locus heterogeneity. Analysis of critical recombinants mapped the NS locus between markers D5S463 and D5S2013, within an !3.5-cM genetic interval. The NS locus is telomeric to the cytokine gene cluster in 5q31. The five known genes encoding casein kinase Ia, the a subunit of retinal rod cGMP phosphodiesterase, the regulator of mitotic-spindle assembly, adrenergic receptor b2, and the diastrophic dysplasia sulfate-transporter gene, as well as the 38 expressed-sequence tags mapped within the critical region, are not obvious candidates. Our study is the first step toward the positional cloning of the NS gene. This finding promises a better understanding of the molecular mechanisms that control epidermal differentiation and immunity.

Bazex-Dupré-Christol syndrome is an inherited condition with skin cancer predisposition characterized by follicular atrophoderma, hypotrichosis, and early onset of multiple basal cell carcinomas. Previous reports suggested an X-linked mode of inheritance. We therefore performed linkage analysis with microsatellite markers of the X chromosome in three families. We obtained evidence for X-linkage and regional assignment to Xq24-q27 of this syndrome (maximal lod score = 5.26 with a recombination fraction of 0% at the DXS1192 locus). This represents a first step towards the identification of a gene involved in hair follicle development and skin tumor formation.

The known role of steroids on the hair follicle leads us to investigate their effects on hair follicle cell angiogenic responses in vitro. We verified, using the immunohistochemical technique, whether human occipital scalp follicle cells express steroid receptors in vitro. We showed that androgen and estrogen receptors were expressed by dermal papilla cells (DPC) and keratinocytes from the outer root sheath in vitro. With regard to steroidal enzymes (type I and II 5alpha-reductases and Cytochrome-p-450-aromatase), the type I 5alpha-reductase gene is much more expressed in DPC than in dermal fibroblasts; however, the type II 5a-reductase gene is transcribed more in dermal fibroblasts than in DPC. The transcription of the two 5alpha-reductase isoform genes in cultured DPC is regulated by a 5alpha-reductase inhibitor. We also demonstrated that DPC, dermal fibroblasts, and outer root shealth keratinocytes expressed cytochrome-p-450-aromatase. Using ELISA and reverse transcriptase-polymerase chain reaction, we investigated the role played by some steroids (estrogens, androgens, antiandrogens) in the modulation of vascular endothelial growth factor (VEGF) expression by DPC. The association of different treatments of DPC (5alpha-reductase inhibitor and androgen receptor antagonist) shows a great stimulation of VEGF and aromatase expression. Strong stimulation of VEGF protein and gene expression is observed in the presence of 17beta-estradiol. Also, the concentration-dependent inhibition of VEGF expression by DPC using the cytochrome-p-450-aromatase inhibitor, confirms the involvement of this estrogenic pathway in the regulation of VEGF expression in vitro.

Phospholipases A2 (PLA2) catalyse the release of fatty acids from the sn-2 position of phospholipids and have been suggested to play a key part in permeability barrier homeostasis. Using a sensitive and versatile fluorometric method, significant PLA2 activity has been detected in both human skin homogenates and tape strippings of stratum corneum. Based on various properties (resistance to heat and sulphuric acid treatment, neutral optimal pH, absolute requirement for millimolar calcium concentrations, inhibition by dithiothreitol and p-bromophenacyl bromide, and resistance to a trifluoromethyl ketone derivative of arachidonic acid, AACOCF3, a specific inhibitor of cytosolic PLA2), this enzyme was characterized as a secretory PLA2 (sPLA2). Immunohistochemistry revealed strong labelling of type I pancreatic sPLA2 at the stratum corneum-stratum granulosum junction, type II sPLA2 being undetectable. An increase in PLA2 activity in tape-stripped material from the deepest level of the stratum corneum was correlated with partial morphological disappearance of type I sPLA2 immunolabelling. Our data thus provide the first convincing evidence that pancreatic sPLA2 is significantly expressed in human epidermis, where it might participate in the accumulation of free fatty acids contributing to the permeability barrier. In addition, our method for determining PLA2 activity in easily available tape strippings should allow further clinical studies aimed to explore possible PLA2 abnormalities in various dermatoses.

Vascular calcifications are common in uremic patients whereas calciphylaxis is rare. We report the case of a 45-year-old woman on chronic hemodialysis since 1977. She had a subtotal parathyroidectomy in 1985, aortic and mitral valve replacement in 1986, and has been treated since then with nicoumalone. In June 1991, she presented with repeated, painful cutaneous necrosis suggesting panniculitis. A skin biopsy showed lobular panniculitis and evidence of calciphylaxis. There was an obvious biological hyperparathyroidism. Protein C functional level was in the normal range whereas protein S functional level was low, i.e. 42%. The patient underwent cervical surgery to remove two parathyroid glands, and daily hemodialysis sessions. Despite this treatment, cutaneous necrosis progressed with superinfection. A few weeks later, the patient died from a septic shock after a myocardic infarction. Necropsy was not performed.

A young woman presented with erosive lesions of the labia minora, which appeared 3 years ago after Stevens-Johnson syndrome. Pathological examination showed 'vulval adenosis'. A similar case has been previously reported. Vaporization by carbon-dioxide laser gave satisfactory results, and after 2 years the patient remains totally cured. We discuss several embryological theories which may explain the mechanism of the vulval adenosis in this patient.