[The cutaneous porphyrias]. / Porphyries cutanées.

The porphyrias are a group of metabolic disorders resulting from an innate abnormality in haem biosynthesis, and the clinical settings of which vary according to the genetic enzyme abnormality in question. These are genetic disorders with autosomal dominant or recessive inheritance of varying penetrance, and whose clinical expression differs according to the preferential location of haem precursors. Different classifications have been proposed according to genetic inheritance, the enzyme anomaly at issue, and clinical expression. The clinical classification distinguishes between acute porphyria (acute intermittent porphyria, porphyria variegata, hereditary coproporphyria), bullous cutaneous porphyrias (porphyria cutanea tarda, porphyria variegata and hereditary coproporphyria), painful photosensitive acute cutaneous porphyrias (erythropoietic protoporphyria and X-linked dominant protoporphyria), and rare recessive porphyrias (congenital erythropoietic porphyria, Doss porphyria, hepatoerythropoietic porphyria and harderoporphyria). Treatment depends on the clinical expression of the disorder.

The Clinical Spectrum of Multiple Endocrine Neoplasia Type 2A with Cutaneous Lichen Amyloidosis in Ethnic Han Chinese.

This study systematically reviewed previous literatures and analyzed the genotype-phenotype relationship between the multiple endocrine neoplasia type 2A (MEN 2A)-cutaneous lichen amyloidosis (CLA) and RET/OSMR/IL31RA mutations. RET/OSMR/IL31RA screening was performed on 8 RET-carriers from 3 independent Chinese MEN 2A families. Besides, 51 MEN 2A-CLA patients in 116 RET carriers from literatures were clustered and analyzed. Our results indicated that almost all MEN 2A-CLA patients exhibited CLA which was located in the scapular region and carried RET mutation at codon 634. Meanwhile, we firstly described MEN 2A-CLA here in Chinese Han patient with RET p.C634F mutation.

Familial hypercholesterolaemia with tuberous and tendinous xanthomas: case report and mutation analysis.

Xanthomas are important clinical manifestations of disordered lipid metabolism, which are mostly found in patients with familial hypercholesterolaemia (FH), an inherited disorder that is predominantly caused by mutations in the low-density lipoprotein receptor gene (LDLR). Tuberous and tendinous xanthomas with wide distribution and large size are rare; however, they may indicate the severity of FH, and tend to be found in homozygous FH. In this study, we investigated the clinical and genetic aspects of a young patient with FH presenting with multiple large masses in various locations. The lesions on the elbows and buttocks were locally excised and subsequently confirmed by biopsy to be xanthomas. Genetic analysis further confirmed that the patient was compound heterozygous for two mutations in both alleles of the LDLR gene. This rare case of compound heterozygous FH presenting with multiple large and widely distributed xanthomas provides a better understanding of FH and xanthomas.

The important role of epidermal triacylglycerol metabolism for maintenance of the skin permeability barrier function.

Survival in a terrestrial, dry environment necessitates a permeability barrier for regulated permeation of water and electrolytes in the cornified layer of the skin (the stratum corneum) to minimize desiccation of the body. This barrier is formed during cornification and involves a cross-linking of corneocyte proteins as well as an extensive remodeling of lipids. The cleavage of precursor lipids from lamellar bodies by various hydrolytic enzymes generates ceramides, cholesterol, and non-esterified fatty acids for the extracellular lipid lamellae in the stratum corneum. However, the important role of epidermal triacylglycerol (TAG) metabolism during formation of a functional permeability barrier in the skin was only recently discovered. Humans with mutations in the ABHD5/CGI-58 (α/ß hydrolase domain containing protein 5, also known as comparative gene identification-58, CGI-58) gene suffer from a defect in TAG catabolism that causes neutral lipid storage disease with ichthyosis. In addition, mice with deficiencies in genes involved in TAG catabolism (Abhd5/Cgi-58 knock-out mice) or TAG synthesis (acyl-CoA:diacylglycerol acyltransferase-2, Dgat2 knock-out mice) also develop severe skin permeability barrier dysfunctions and die soon after birth due to increased dehydration. As a result of these defects in epidermal TAG metabolism, humans and mice lack ω-(O)-acylceramides, which leads to malformation of the cornified lipid envelope of the skin. In healthy skin, this epidermal structure provides an interface for the linkage of lamellar membranes with corneocyte proteins to maintain permeability barrier homeostasis. This review focuses on recent advances in the understanding of biochemical mechanisms involved in epidermal neutral lipid metabolism and the generation of a functional skin permeability barrier. This article is part of a Special Issue entitled The Important Role of Lipids in the Epidermis and their Role in the Formation and Maintenance of the Cutaneous Barrier. Guest Editors: Kenneth R. Feingold and Peter Elias.

Assessment of the influence of HLA class I and class II loci on the prevalence of keloid disease in Jamaican Afro-Caribbeans.

Keloid disease (KD) is a common abnormal cutaneous fibrotic disorder of unknown aetiopathogenesis. KD is reported to have a strong genetic component as it is often familial and has a high incidence in certain ethnicities, in particular those of Afro-Caribbean origin. Genetic risk factors combined with aberrant lesional inflammatory responses point to the human leukocyte antigen (HLA) system as a viable target for investigating disease aetiology. Sequence specific primer polymerase chain reaction with allele sequencing was used to determine HLA-DQA1 and DQB1 allele frequencies (AF) for 165 KD patients and 119 healthy controls of black Jamaican Afro-Caribbean origin. HLA class I alleles A*01, A*03, A*25, B*07 and Cw*08:02, previously identified as KD associated in a different ethnicity, were also analysed. Allele sequencing confirmed typing accuracy but no statistically significant differences in AF were identified between KD patients and controls. Furthermore, KD subgroups including patient gender, family history and multiple- or single-site scarring did not show significant allele-disease associations.

The molecular skin pathology of familial primary localized cutaneous amyloidosis.

Familial primary localized cutaneous amyloidosis (FPLCA) is an autosomal dominant disorder associated with chronic itching and skin lichenification. In lesional skin, there are apoptotic basal keratinocytes and deposits of amyloid material on degenerate keratin filaments in the upper dermis. The genetic basis of FPLCA involves mutations in the OSMR and IL31RA genes but the disease pathophysiology is not fully understood. In this study, we identified new pathogenic heterozygous missense mutations in the OSMR gene (p.Val631Leu and p.Asp647Tyr) in two Dutch FPLCA families. We then compared gene expression profiles between FPLCA lesional skin (n = 4) and site-matched control skin (n = 6). There was twofold or greater upregulation of 34 genes and downregulation of 43 genes. Most changes in gene expression (verified by quantitative RT-PCR) reflected alterations in epidermal differentiation and proliferation consistent with lichenification, but we also noted a reduction in several interfollicular keratinocyte stem cell markers in FPLCA skin. Differences in gene expression were also noted for proteins involved in apoptosis and nerve conduction. Collectively, this study expands the molecular basis of FPLCA and provides new insight into the skin pathology of this condition.

Laminopathies: multisystem dystrophy syndromes.

Laminopathies are a heterogeneous group of genetic disorders due to abnormalities in type A lamins and can manifest varied clinical features affecting many organs including the skeletal and cardiac muscle, adipose tissue, nervous system, cutaneous tissue, and bone. Mutations in the gene encoding lamins A and C (LMNA) cause primary laminopathies, including various types of lipodystrophies, muscular dystrophies and progeroid syndromes, mandibuloacral dysplasia, dilated cardiomyopathies, and restrictive dermopathy. The secondary laminopathies are due to mutations in ZMPSTE24 gene which encodes for a zinc metalloproteinase involved in processing of prelamin A into mature lamin A and cause mandibuloacral dysplasia and restrictive dermopathy. Skin fibroblast cells from many patients with laminopathies show a range of abnormal nuclear morphology including bleb formation, honeycombing, and presence of multi-lobulated nuclei. The mechanisms by which mutations in LMNA gene cause multisystem dystrophy are an active area of current investigation. Further studies are needed to understand the underlying mechanisms of marked pleiotropy in laminopathies.

[Inherited metabolic disorders with cutaneous manifestations]. / Hereditäre Stoffwechselerkrankungen mit kutaner Manifestation.

Over the last years, the genetic basis of several monogenic inherited metabolic diseases has been elucidated. Interestingly, some of these disorders manifest with characteristic cutaneous symptoms that are often crucial for diagnosis. In most cases, however, besides the skin other organs are affected. Therefore, an interdisciplinary supervision of these patients is highly important. In this review we will discuss diseases that constitute a challenge not only for dermatologists but also for physicians from other specialties. A particular emphasis is put on genetic and clinical features of these disorders as well as current therapeutic concepts.

Frequent association between MEN 2A and cutaneous lichen amyloidosis.

OBJECTIVE: Multiple endocrine neoplasia type 2A (MEN 2A) and familial medullary thyroid carcinoma (FMTC) are genetic diseases due to activating mutations of the RET proto-oncogene. Affected patients develop medullary thyroid carcinoma (100%), in an isolated form (FMTC) or in association with phaeochromocytoma (30-50%), and primary hyperparathyroidism (10-20%) (MEN 2A). The presence of cutaneous lichen amyloidosis (CLA) has been anecdotally described in few families harbouring RET proto-oncogene mutation in codon 634. The aim of the study was to evaluate the incidence of CLA in MEN 2A/FMTC families. PATIENTS AND DESIGN: Ten MEN 2A/FMTC families were studied and RET gene mutations identified in all. Complete dermatological assessment was carried out in each family member. Skin biopsy for histological studies was performed in patients with CLA. RESULTS: Among 10 MEN 2A/FMTC families, the presence of CLA was found only in patients belonging to the three families with MEN 2A and RET mutation in codon 634. Nine of 25 patients (36%) with codon 634 mutation presented CLA, though two of them did not show CLA skin lesions but the typical neurological pruritus in the upper back. In all patients, neurological pruritus was present since infancy as a precocious marker of the disorder. The dermatological study of patients with CLA skin lesions added further evidence that pruritus has a pivotal role in the development of CLA, the amyloid deposition being the consequence of repeated scratching. Light microscopy revealed orthokeratotic hyperkeratosis, with elongation of the rete ridges, rare intramalpighian apoptic keratinocytes and deposits of amorphous material in the superficial dermis. Examination under ultraviolet light showed thioflavin T-positive staining, confirming the presence of amyloid in the papillary dermis. The use of Capsaicin at the dilution of 0.025% had a mild efficacy on the cutaneous symptoms. CONCLUSIONS: Among the members of the three families with MEN 2A and RET 634 mutation, the incidence of CLA was 36%, a figure similar to that reported in the literature for phaeochromocytoma (30-50%) and even higher than that for hyperparathyroidism (10-20%). The present data confirm that CLA is linked to codon 634 RET mutations and is a precocious marker of the disorder.