Molecular genetic aspects of the phakomatoses: tuberous sclerosis complex and neurofibromatosis 1

[Tuberous sclerosis: evaluation of myofibroblasts in cutaneous angiofibromas - case report]

Tuberous sclerosis is a rare autosomal dominant disorder. Myofibroblasts are cells with a hybrid phenotype between fibroblasts and smooth muscle cells. The objective of this study is to describe clinical and histopathological characteristics of tuberous sclerosis and to conduct an immunohistochemical evaluation of myofibroblasts in cutaneous angiofibromas present in this condition. Lesion sections removed were stained with hematoxylin-eosin and Masson's trichrome. Immunohistochemistry against alpha-SMA was done to determine the presence of myofibroblasts, and the reaction was negative. Since alpha-SMA is a specific marker for myofibroblasts, this result suggests that myofibroblasts are not involved in cutaneous angiofibromas present in the tuberous sclerosis case reported.

Double phakomatosis; neurofibromatosis type-1 and tuberous sclerosis

Neurocutaneous syndromes represent some of the most common inherited disorders of the nervous system. Neurofibromatosis type-1 (NF-1) and tuberous sclerosis are well described. Yet, the presentation of both syndromes in the same patient is quite rare. We performed a thorough review of the literature of such double phakomatosis including pattern of inheritance. Eleven cases were reported in the literature. In addition we report a young patient who presented with clinical picture suggestive of both NF-1 and tuberous sclerosis, and present a radiographic and histopathological description of the case.

Tuberous sclerosis complex and epilepsy: recent developments and future challenges

Tuberous sclerosis complex (TSC) is a congenital syndrome characterized by the widespread development of benign tumors in multiple organs, caused by mutations in one of the tumor suppressor genes, TSC1 or TSC2. About 80% of affected patients have a new mutation, and the remaining 20% have inherited a TSC gene mutation from a parent. The disorder affects approximately 1 in 6000 individuals. Cortical tubers are the neuropathological hallmark of TSC. The most common neurological manifestations of TSC are epilepsy, mental retardation, and autistic behavior. Epilepsy occurs in up to 80-90% of patients and is often intractable, with a poor response to anticonvulsant medications. While the molecular basis of TSC is well established, far less is known about the mechanisms of epilepsy in this disorder. In this article, we first summarize known clinical aspects of TSC with emphasis on its neurological features. Then, based on the molecular, pathological, immunohistochemical, neurochemical, and physiological properties of tubers in patients with TSC and in animal models, we discuss possible mechanisms of seizures and epileptogenesis in TSC. Finally, we provide an updated literature review and a consensus statement from the Tuberous Sclerosis Complex Working Group for future research into the mechanisms of epilepsy in TSC.

Dermatologia comparativa

Demonstra-se o quadro exuberante dos angiofibromas faciais em paciente do sexo masculino, de 32 anos, com esclerose tuberosa, os quais podem ser comparados com amoras.

Neurofibromatoses et sclérose tubéreuse de bourneville

Neurofibromatoses and tuberous sclerosis have specific genetic epidemiology, diagnostic criteria and management. These diseases are autosomal dominant disorders linked to mutations on tumour suppressor genes. Their management is mainly clinically oriented and aimed at managing potential complications.

Tuberous sclerosis complex and neurofibromatosis type 1: the two most common neurocutaneous diseases

TSC and NF1 are the most common of the neurocutaneous diseases, and both are autosomal dominant with a high spontaneous mutation rate. For diagnosis, two features are necessary for each disease. Skin findings for each are especially helpful for diagnosis, as is neuroimaging in TSC. For NF1, neuroimaging is not yet reliable for diagnosis. In children, brain symptoms cause most of the morbidity in TSC, and nerve sheath and nervous system tumors as well as learning disabilities cause major morbidity in NF1. Renal disease becomes a serious problem for adults with TSC. The TSC1, TSC2, and NF1 genes function as tumor suppressor genes and have other functions that are being investigated. Blood tests for diagnosis have a high false-negative rate. Therapies for TSC and for NF1 are both medical and surgical.

Neutrophil elastase mutations in congenital neutropenia

Severe congenital neutropenia (SCN) was originally described as an autosomal recessive disorder. Autosomal dominant and sporadic forms of the disease have subsequently been recognized. All forms of the disease are manifest by persistent severe neutropenia and recurrent bacterial infection. Cyclical neutropenia (CyN) is characterized by periodic neutropenia inter-spaced with (near) normal neutrophil counts. Recently, heterozygous mutations in the ELA2 gene encoding neutrophil elastase (NE) have been described in the majority of cases of CyN and sporadic and autosomal dominant SCN. A case of paternal mosaicism has provided genetic "proof" of the pathogenicity of such mutations, but the exact pathogenic mechanism remains elusive. This review will focus on the mosaic proof and examine possible pathogenic mechanisms. The lack of obvious associations and indeed overlap between the mutations that cause the two diseases will also be discussed. Clinically to date, the discovery of an elastase mutation has been of limited value to individual patients. However, it is hoped that further genotype/phenotype studies may improve assessment of patient prognosis.

Progress in molecular genetics of heritable skin diseases: the paradigms of epidermolysis bullosa and pseudoxanthoma elasticum

The 42nd Annual Symposium on the Biology of the Skin, entitled "The Genetics of Skin Disease", was held in Snowmass Village, Colorado, in July 1993. That meeting presented the opportunity to discuss how modern approaches to molecular genetics and molecular biology could be applied to understanding the mechanisms of skin diseases. The published proceedings of this meeting stated that "It is an opportune time to examine the genetics of skin disease" (Norris et al, 1994). Indeed, this meeting just caught the wave of early pioneering studies that have helped us to understand the molecular basis of a large number of genodermatoses. This overview presented in the 50th Annual Symposium on the biology of the skin, highlights the progress made in the molecular genetics of heritable skin diseases over the past decade.

Developmental neurogenetics and neuro-ophthalmology

The field of developmental neurogenetics has burgeoned over the past decade. Through the combined efforts of developmental biologists, geneticists, and clinicians, genetic defects resulting in neuro-ophthalmic disorders such as holoprosencephaly, microphthalmia, dominant optic atrophy, and optic nerve colobomas have been identified and characterized at the molecular level. Experimental studies in model organisms are continuing to identify novel genes critical for ocular and central nervous system development. Mutations in some of these genes have revealed a spectrum of pathology similar to that observed in septo-optic dysplasia, Möebius syndrome, and Duane retraction syndrome. This review examines our current knowledge of the molecular genetics of neuro-ophthalmic disease and focuses on several candidate genes for afferent and efferent visual system disorders.

Tuberous sclerosis complex and neurofibromatosis type 1: the two most common neurocutaneous diseases

TSC and NF1 are the most common of the neurocutaneous diseases, and both are autosomal dominant with a high spontaneous mutation rate. For diagnosis, two features are necessary for each disease. Skin findings for each are especially helpful for diagnosis, as is neuroimaging in TSC. For NF1, neuroimaging is not yet reliable for diagnosis. In children, brain symptoms cause most of the morbidity in TSC, and nerve sheath and nervous system tumors as well as learning disabilities cause major morbidity in NF1. Renal disease becomes a serious problem for adults with TSC. The TSC1, TSC2, and NF1 genes function as tumor suppressor genes and have other functions that are being investigated. Blood tests for diagnosis have a high false-negative rate. Therapies for TSC and for NF1 are both medical and surgical.