Recurrent Mutations in the Basic Domain of TWIST2 Cause Ablepharon Macrostomia and Barber-Say Syndromes.

Ablepharon macrostomia syndrome (AMS) and Barber-Say syndrome (BSS) are rare congenital ectodermal dysplasias characterized by similar clinical features. To establish the genetic basis of AMS and BSS, we performed extensive clinical phenotyping, whole exome and candidate gene sequencing, and functional validations. We identified a recurrent de novo mutation in TWIST2 in seven independent AMS-affected families, as well as another recurrent de novo mutation affecting the same amino acid in ten independent BSS-affected families. Moreover, a genotype-phenotype correlation was observed, because the two syndromes differed based solely upon the nature of the substituting amino acid: a lysine at TWIST2 residue 75 resulted in AMS, whereas a glutamine or alanine yielded BSS. TWIST2 encodes a basic helix-loop-helix transcription factor that regulates the development of mesenchymal tissues. All identified mutations fell in the basic domain of TWIST2 and altered the DNA-binding pattern of Flag-TWIST2 in HeLa cells. Comparison of wild-type and mutant TWIST2 expressed in zebrafish identified abnormal developmental phenotypes and widespread transcriptome changes. Our results suggest that autosomal-dominant TWIST2 mutations cause AMS or BSS by inducing protean effects on the transcription factor's DNA binding.

Revised nomenclature and classification of inherited ichthyoses: results of the First Ichthyosis Consensus Conference in Sorèze 2009.

BACKGROUND: Inherited ichthyoses belong to a large, clinically and etiologically heterogeneous group of mendelian disorders of cornification, typically involving the entire integument. Over the recent years, much progress has been made defining their molecular causes. However, there is no internationally accepted classification and terminology. OBJECTIVE: We sought to establish a consensus for the nomenclature and classification of inherited ichthyoses. METHODS: The classification project started at the First World Conference on Ichthyosis in 2007. A large international network of expert clinicians, skin pathologists, and geneticists entertained an interactive dialogue over 2 years, eventually leading to the First Ichthyosis Consensus Conference held in Sorèze, France, on January 23 and 24, 2009, where subcommittees on different issues proposed terminology that was debated until consensus was reached. RESULTS: It was agreed that currently the nosology should remain clinically based. "Syndromic" versus "nonsyndromic" forms provide a useful major subdivision. Several clinical terms and controversial disease names have been redefined: eg, the group caused by keratin mutations is referred to by the umbrella term, "keratinopathic ichthyosis"-under which are included epidermolytic ichthyosis, superficial epidermolytic ichthyosis, and ichthyosis Curth-Macklin. "Autosomal recessive congenital ichthyosis" is proposed as an umbrella term for the harlequin ichthyosis, lamellar ichthyosis, and the congenital ichthyosiform erythroderma group. LIMITATIONS: As more becomes known about these diseases in the future, modifications will be needed. CONCLUSION: We have achieved an international consensus for the classification of inherited ichthyosis that should be useful for all clinicians and can serve as reference point for future research.

Pagetoid reticulosis with CD30 positivity and cytotoxic/suppressor cells.

Pagetoid reticulosis (PR) is a low-grade primary cutaneous T-cell lymphoma that usually presents as a solitary, slowly enlarging erythematous or hyperkeratotic plaque on the distal areas of the extremities. Histopathologically, it is characterized by a dense, band-like infiltrate of atypical lymphocytes with prominent epidermotropism within a hyperplastic epidermis, and immunophenotypic studies show in most cases, a CD4-positive T-helper phenotype for the neoplastic lymphocytes. We describe an African man with a more than 20-year history of an acral lesion of PR, which was histopathologically characterized by lymphocyte immunophenotype consisting of CD8- and CD30-positive cells. We discuss the differential diagnosis with other primary cutaneous lymphoproliferative disorders showing similar immunophenotype. This case shows that CD30-positive PR should be included as a rare variant within the spectrum of CD30-positive primary cutaneous lymphoproliferative disorders. As in other primary cutaneous CD30-positive lymphoproliferative processes, lesions of CD30-positive PR show an indolent course and a benign biological behavior.

Bathing-suit ichthyosis. A peculiar phenotype of lamellar ichthyosis in South African blacks.

Autosomal recessive congenital ichthyosis is a heterogeneous group of disorders of cornification showing a wide spectrum of clinical phenotypes.Here, thirteen cases of a so far unreported distinct type of autosomal recessive congenital ichthyosis are described. All the skin lesions were present at birth and ten were then compatible with collodion baby. Shedding of the collodion led to an ichthyotic condition with a very characteristic distribution of the lesions which involved the trunk, the most proximal parts of the upper limbs, scalp and neck but spared the central face and extremities. The term "bathing-suit" ichthyosis is suggested for this unusual phenotype of lamellar ichthyosis.