两个弥漫性掌跖角化病家系的病理特征与基因突变分析

为了明确两个弥漫性掌跖角化病家系的临床、病理特征、角蛋白9在局部组织中的表达情况及KRT9基因的突变, 对2名先证者的手掌皮肤进行组织病理学、免疫组织化学分析, 并用聚合酶链反应技术及直接测序分析的方法, 对家系中46名成员的KRT9基因进行突变分析。发现两名先证者的表皮都呈显著的角化过度, 颗粒层和棘层明显增厚, 真皮浅层有轻度的炎症细胞浸润, 上基底的棘层和颗粒层的角质形成细胞中都有特征性的空泡变性存在; 角蛋白9只在棘层和颗粒层的角质形成细胞中特异性表达; 两个家系患者分别存在KRT9基因的点突变N160S和L167S; 说明这两个家系都属于表皮松解性掌跖角化病家系, KRT9基因N160S和L167S突变分别导致这两个家系发病。     

The Effects of a Mutant Connexin 26 on Epidermal Differentiation

To elucidate the mode of action of dominant mutant connexins in causing inherited skin diseases, transgenic mice were produced that express the true Vohwinkel syndrome-associated mutant Cx26 (D66H), from a keratin 10 promoter, specifically in the suprabasal epidermal keratinocytes. Following birth, the transgenic mice developed keratoderma similar to that of human carriers of Cx26 (D66H). Expression of the transgene resulted in a loss of Cx26 and Cx30 at intercellular junctions of epidermal keratinocytes and accumulation of these connexins in the cytoplasm. Injection of primary mouse keratinocytes with Lucifer Yellow showed no difference in terms of dye spreading between transgenic and non transgenic keratinocytes in vitro. Expression of the mutant Cx26 (D66H) did not interfere with the formation of the epidermal water barrier during late embryonic development. Attempts to produce transgenic mice expressing the wild type form of Cx26 from the K10 promoter failed to produce viable animals although transgenic embryos were recovered at days 9 and 12 of gestation, suggesting that the transgene might be embryonic lethal.     

KRT9 gene mutation as a reliable indicator in the prenatal molecular diagnosis of epidermolytic palmoplantar keratoderma

Epidermolytic palmoplantar keratoderma (EPPK) is the most frequent form of such keratodermas. It is inherited in an autosomal dominant pattern and is clinically characterized by diffuse yellowish thickening of the skin on the palms and soles with erythematous borders during the first weeks or months after birth. EPPK is generally caused by mutations of the KRT9 gene. More than 26 KRT9 gene mutations responsible for EPPK have been described (Human Intermediate Filament Database, www.interfil.org), and many of these variants are located within the highly-conserved coil 1A region of the α-helical rod domain of keratin 9. Unfortunately, there is no satisfactory treatment for EPPK. Thus, prenatal molecular diagnosis or pre-pregnancy diagnosis is crucial and benefits those affected who seek healthy descendants. In the present study, we performed amniotic fluid-DNA-based prenatal testing for three at-risk pregnant EPPK women from three unrelated southern Chinese families who carried the KRT9 missense mutations p.Arg163Trp and p.Arg163Gln, and successfully helped two families to bear normal daughters. We suggest that before the successful application of preimplantation genetic diagnosis (PGD), and noninvasive prenatal diagnosis of EPPK that analyzes fetal cells or cell-free DNA in maternal blood, prenatal genetic diagnosis by amniocentesis or chorionic villus sampling (CVS) offers a quite acceptable option for EPPK couples-at-risk to avoid the birth of affected offspring, especially in low- and middle-income countries.     

Connexin 26 Expression and Mutation Analysis in Epidermal Disease

Gap junctional communication has a key role in the co-ordination of keratinocyte differentiation. Multiple connexins are expressed in the epidermis and mutations in four of these connexins are associated with disorders of keratinisation. Specific autosomal dominant Cx26 mutations have been associated with syndromes of skin disease and hearing loss. Here we describe the characterization of a new Cx26 polyclonal antibody raised against the cytoplasmic region of the protein. It has been used to investigate Cx26 protein localization in epidermal disease and in the study of mutant Cx26 proteins.