Pamela Poblete‐Gutiérrez

Allelic loss underlies type 2 segmental Hailey-Hailey disease, providing molecular confirmation of a novel genetic concept

Hailey-Hailey disease (HHD) is an autosomal dominant trait characterized by erythematous and oozing skin lesions preponderantly involving the body folds. In the present unusual case, however, unilateral segmental areas along the lines of Blaschko showing a rather severe involvement were superimposed on the ordinary symmetrical phenotype. Based on this observation and similar forms of mosaicism as reported in other autosomal dominant skin disorders, we postulated that in such cases, 2 different types of segmental involvement can be distinguished. Accordingly, the linear lesions as noted in the present case would exemplify type 2 segmental HHD. In the heterozygous embryo, loss of heterozygosity occurring at an early developmental stage would have given rise to pronounced linear lesions reflecting homozygosity or hemizygosity for the mutation. By analyzing DNA and RNA derived from blood and skin samples as well as keratinocytes of the index patient with various molecular techniques including RT-PCR, real-time PCR, and microsatellite analysis, we found a consistent loss of the paternal wild-type allele in more severely affected segmental skin regions, confirming this hypothesis for the first time, to our knowledge, at the molecular and cellular level.

Mutations in the gene encoding the Wnt-signaling component R-spondin 4 (RSPO4) cause autosomal recessive anonychia.

Anonychia is an autosomal recessive disorder characterized by the congenital absence of finger- and toenails. In a large German nonconsanguineous family with four affected and five unaffected siblings with isolated total congenital anonychia, we performed genomewide mapping and showed linkage to 20p13. Analysis of the RSPO4 gene within this interval revealed a frameshift and a nonconservative missense mutation in exon 2 affecting the highly conserved first furin-like cysteine-rich domain. Both mutations were not present among controls and were shown to segregate with the disease phenotype. RSPO4 is a member of the recently described R-spondin family of secreted proteins that play a major role in activating the Wnt/ beta -catenin signaling pathway. Wnt signaling is evolutionarily conserved and plays a pivotal role in embryonic development, growth regulation of multiple tissues, and cancer development. Our findings add to the increasing body of evidence indicating that mesenchymal-epithelial interactions are crucial in nail development and put anonychia on the growing list of congenital malformation syndromes caused by Wnt-signaling-pathway defects. To the best of our knowledge, this is the first gene known to be responsible for an isolated, nonsyndromic nail disorder.

Diffuse and segmental variants of cutaneous leiomyomatosis: novel mutations in the fumarate hydratase gene and review of the literature

Abstract:  Multiple cutaneous and uterine leiomyomatosis (MCUL; OMIM 150800) is an autosomal dominantly inherited disease characterized by leiomyomas of the skin and uterine leiomyomas. Recently, association of MCUL with different forms of renal cancer has been described. This syndrome is referred to as hereditary leiomyomatosis and renal cell cancer (OMIM 605839). Both disorders result from heterozygous germline mutations in the fumarate hydratase (FH) gene that may function as a tumor suppressor. Interestingly, cutaneous leiomyomas do not only manifest in a diffuse and symmetric fashion. Rather frequently, a segmental or band‐like manifestation pattern can be observed, usually following the lines of Blaschko. Here, we sought to elucidate the molecular basis of diffuse and segmental cutaneous leiomyomatosis in six unrelated Dutch and Spanish patients and their families. We identified six novel FH mutations, including one missense and one nonsense mutation, two deletions and two splice‐site mutations. The segmental phenotype that was observed in various patients with FH mutations most likely reflects a type 2 segmental manifestation of cutaneous leiomyomatosis as previously also described for other autosomal dominantly inherited skin diseases. The results presented here extend the current data on the molecular basis of familial cutaneous leiomyomatosis and comprise, to the best of our knowledge, the first genetic study in Dutch and Spanish patients with this disorder. In addition, we review the clinical and molecular aspects of the disease.

Porphyria cutanea tarda--when skin meets liver.

Porphyria cutanea tarda (PCT) is the most frequent type of porphyria worldwide and results from a catalytic deficiency of uroporphyrinogen decarboxylase (UROD), the fifth enzyme in heme biosynthesis. At least two different types of PCT are currently distinguished: an acquired variant, also referred to as sporadic or type I PCT, in which the enzymatic deficiency is limited to the liver; and an autosomal dominantly inherited form, also known as familial or type II PCT, in which there is a decrease of enzymatic activity in all tissues. The cutaneous findings include increased photosensitivity, skin fragility, blistering, erosions, crusts, and miliae on the sun-exposed areas of the body. Additionally, hyperpigmentation, hypertrichosis, sclerodermoid plaques, and scarring alopecia might be observed. In patients with type I PCT, there is a significant association with liver disease that can be triggered by genetic and environmental factors, such as alcohol abuse, iron overload, haemochromatosis, polychlorinated hydrocarbons, and hepatitis C virus infection. The diagnosis of PCT can be made based on the skin symptoms, a characteristic urinary porphyrin excretion profile, and the detection of isocoproporphyrin in the feces. In red blood cells of individuals with type II PCT, UROD activity is decreased by approximately 50% due to heterozygous mutations in the UROD gene. Here we provide an update on clinical, diagnostic and therapeutic aspects of PCT, a disorder that affects both skin and liver.

The acute hepatic porphyrias: current status and future challenges.

The porphyrias are predominantly inherited metabolic disorders, which result from a specific deficiency of one of the eight enzymes along the pathway of haem biosynthesis. Historically, they have been classified into hepatic and erythropoietic forms, based on the primary site of expression of the prevailing dysfunctional enzyme. From a clinical point of view, however, it is more convenient to subdivide them into acute and non-acute porphyrias, thereby primarily considering the potential occurrence of life-threatening acute neurovisceral attacks. Unrecognised or untreated, such an acute porphyric attack is associated with a significant mortality of up to 10%. The acute hepatic porphyrias comprise acute intermittent porphyria, variegate porphyria, hereditary coproporphyria, and δ-aminolevulinic acid dehydratase deficiency porphyria. Making a precise diagnosis may be difficult because the different types of porphyrias may show overlapping clinical and biochemical characteristics. To date, the therapeutic possibilities are limited and mainly symptomatic. In this overview we report on what is currently known about pathogenesis, clinic, diagnostics, and therapy of the acute hepatic porphyrias. We further point out actual and future challenges in the management of these diseases.

Molecular heterogeneity of familial porphyria cutanea tarda in Spain: characterization of 10 novel mutations in the UROD gene

Background  Porphyria cutanea tarda (PCT) results from decreased hepatic uroporphyrinogen decarboxylase (UROD) activity. In the majority of patients, the disease is sporadic (S‐PCT or type I) and the enzyme deficiency is limited to the liver. Familial PCT (F‐PCT or type II) is observed in 20–30% of patients in whom mutations on one allele of the UROD gene reduce UROD activity by approximately 50% in all tissues. Another variant of PCT (type III) is characterized by family history of the disease although it is biochemically indistinguishable from S‐PCT.

Hepatocellular carcinoma in variegate porphyria: a serious complication.

Variegate porphyria is an acute hepatic porphyria resulting from a partial deficiency of protoporphyrinogen oxidase, the penultimate enzyme in haem biosynthesis. Cutaneous symptoms and acute neurovisceral attacks are well-known clinical characteristics of the disease. Less studied, however, is the risk of developing hepatocellular carcinoma, an aggressive type of liver cancer. We describe here two Swiss patients with variegate porphyria and this serious complication. Common risk factors, including alcohol over-consumption or chronic hepatitis, were absent in both patients. Interestingly, one patient carried mutation 1082-1083insC in the PPOX gene, a prevalent sequence deviation in the Swiss variegate porphyria population, which was also found in a French patient with variegate porphyria and hepatocellular carcinoma. Recent studies indicate that individuals with acute hepatic porphyria have a 36- to 61-fold increased risk of manifesting hepatocellular carcinoma. The incidence rate ratio in the Swiss population was estimated to be 34, comparable with those found in the French and Finnish populations. Because this tumour is associated with a rising mortality, we suggest regular screening for hepatocellular carcinoma in all patients with variegate porphyria.

Auriculotemporal syndrome in childhood.

Sir, Because of the broad variability of clinical manifestations, paediatric dermatologists and allergologists are sometimes confronted with diagnostic difficulties when assessing food-associated reactions of the skin in children, particularly if allergological tests do not reveal any pathological results and specific elimination diets are ineffective. In these cases, children can suffer from rare diseases mimicking the cutaneous signs of food allergy. One of these diseases is the auriculotemporal syndrome, also known as Frey’s disease. Whereas it is more frequently observed in adults, e.g. after surgery to the parotid or submandibular glands, its overall occurrence in children has to be considered rare. The disease presents with a well-demarcated facial erythema and hyperhidrosis, which can be unilateral or bilateral, and, after a while, usually resolves spontaneously (3 – 5).

Molecular pathways involved in hair follicle tumor formation: all about mammalian target of rapamycin?

Abstract:  Hair follicle tumors show a broad range of phenotypic variability and diverse histopathological characteristics. To date, different genes and signalling cascades have been implicated in the development and growth of these tumors including the sonic hedgehog, nuclear factor kappa‐B and wingless pathway. While the former three have received ample attention, little is known about the possible role of mammalian target of rapamycin (mTOR) in trichofollicular tumorigenesis. Here, we delineate how mTOR can link the various signalling pathways, thereby proposing a unifying model for hair follicle tumor formation.

Bleomycin‐induced flagellate dermatitis

A 62‐year‐old man with testis carcinoma was treated with bleomycin, cisplatin, and etoposide (BEP). During the second cycle of this chemotherapeutic regimen, he developed nonpruritic, linear erythematous lesions in a flagellate‐like fashion on the trunk and extremities. After a short‐term oral prednison therapy and ceasing bleomycin administration, these lesions completely resolved. Herein, the characteristic cutaneous side effects of bleomycin are discussed.