类脂质蛋白沉积症两家系调查及ECM1基因突变检测

目的:检测类脂质蛋白沉积症二家系中细胞外基质蛋白(ECM1)基因突变位点。方法:提取1号家系先证者及其母亲,2号家系先证者、父母、配偶及儿子外周血DNA。PCR技术扩增ECM1基因编码序列,采用一代Sanger法对PCR扩增产物进行测序。结果:1号家系先证者在7号外显子发现已知突变(纯合突变c.960GA),其母亲为杂合携带者;2号家系先证者为遗传复合体,是上述突变位点的杂合携带者,此外在3号外显子上存在1个插入突变c.142insC。结论:类脂质蛋白沉积症存在遗传异质性。     

Lipoid proteinosis: phenotypic heterogeneity in Iranian families with c.507delT mutation in ECM1

Lipoid proteinosis (LP) is a rare autosomal recessive genodermatosis caused by loss‐of‐function mutations in the ECM1 gene, and previous studies have noted phenotypic variability. In this study, we examined 12 patients representing three Iranian families for clinical manifestations and genotyped them for mutations in ECM1. LP was diagnosed with characteristic mucocutaneous and neurologic manifestations. Five patients were also subjected to magnetic resonance imaging (MRI)/computed tomography (CT) scan of the central nervous system. DNA was isolated from peripheral blood from patients and their clinically unaffected relatives, and mutations in ECM1 were sought by PCR‐based amplification of all exons and flanking intronic sequences, followed by bidirectional Sanger sequencing. Significant phenotypic variability in this multisystem disorder, including presence of convulsions and epilepsy in about half of the patients was noted. In most cases, this was associated with calcifications in the brain detected by MRI/CT scans. Genotyping of the affected individuals in three families from the central region of Iran revealed presence of homozygous c.507delT mutation in ECM1, reflecting the observed consanguinity in these families. This large cohort revealed extensive phenotypic variability in individuals with the same mutation in ECM1. This observation suggests a role for genetic and epigenetic as well as environmental modulation of the phenotype. Identification of mutations allows screening of unaffected individuals for presence or absence of this mutation in extended LP families, with implications for genetic counseling.     

Treatment of lipoid proteinosis with acitretin in two patients from two unrelated Chinese families with novel nonsense mutations of the ECM1 gene

Lipoid proteinosis is a rare recessive genetic disorder caused by loss‐of‐function mutations to chromosome 1 at 1q21, the extracellular matrix protein 1 (ECM1) gene. Two children with lipoid proteinosis were reported from two unrelated Chinese families, both manifesting with a typical hoarse voice, white acne‐like atrophic lesions and scarring on the skin, and beaded papules around the eyelids. The diagnosis had been confirmed by laboratory tests, skin biopsy and laryngoscope examination. Genomic DNA sequencing was performed for both children and their family members. The two children were treated with acitretin for 6 months and followed up for 1 year. Genomic DNA sequencing of the ECM1 gene showed a novel homozygous nonsense mutation of C1522>T (p.R508X) at exon 10 in one patient, and a novel compound heterozygote for a nonsense/frame‐shift combination of mutations of R281X/1596delG at exons 7 and 10 in the other patient. The symptom of hoarse voice was improved by 6‐month treatment with acitretin, while there was no improvement in the skin lesions. These results demonstrated that acitretin treatment may have efficacy for some of patients with lipoid proteinosis, with superior effect on laryngeal symptoms than skin lesions. However, the conclusive therapeutic effect and underlying mechanisms remain to be further investigated.     

Lipoid proteinosis in two siblings: a report from India

Lipoid proteinosis is an autosomally recessive genodermatosis characterized by widespread deposition of eosinophilic hyaline-like material in the skin, mucous membranes, and other internal organs. Occurrence of lipoid proteinosis in siblings is very rare. We report two siblings from the Indian subcontinent with the classical features of lipoid proteinosis. Both the siblings had had hoarseness of voice and spontaneous vesicular eruptions healing with atrophic scars since their early childhood. They had diffuse waxy thickening of the skin along with beaded papules along the eyelid margin. The tongue was also infiltrated. Skin biopsy demonstrated periodic acid Schiff (PAS) positive eosinophilic material around the blood vessels and appendages.     

Expression of extracellular matrix protein 1 (ECM1) in human skin is decreased by age and increased upon ultraviolet exposure

BACKGROUND: The extracellular matrix protein 1 (ECM1) is expressed in human skin and plays an important role in its normal structure and function. In the rare genetic skin disease lipoid proteinosis, which is characterized by a loss-of-function mutation in the ECM1 gene, skin areas habitually exposed to the sun may show a more severely scarred and photoaged appearance. However, no data are available on the possible involvement of ECM1 expression in intrinsic and extrinsic skin ageing. OBJECTIVES: We hypothesized that ECM1 expression in human skin is regulated by age- and ultraviolet (UV)-dependent mechanisms. METHODS: Skin biopsies from 12 patients with histologically confirmed solar elastosis, from non-UV-exposed sites of 12 age-matched controls and 12 young subjects were analysed. To evaluate the influence of acute UV exposure, buttock skin of 10 healthy subjects was irradiated repetitively on 10 days with a solar simulator and compared intraindividually with non-UV-treated contralateral sites. The expression of ECM1 was investigated by immunohistochemistry using an ECM1 antibody detecting ECM1a and ECM1c isoforms. Semiquantitative analysis of staining intensity was carried out by densitometric image analysis. RESULTS: In normal human skin ECM1a and ECM1c are expressed mainly in the basal cell layers of epidermal keratinocytes and in dermal vessels. For the first time, an expression in the outer root sheath of hair follicles, in sebaceous lobules and epithelium of sweat glands is described. Intrinsically (UV-protected) aged skin shows a significantly reduced expression in basal and upper epidermal cell layers compared with young skin. In photoaged skin, expression is significantly increased within the lower and upper epidermis compared with age-matched UV-protected sites. Importantly, after acute UV exposure in young healthy subjects expression of ECM1 is markedly increased in both lower and upper epidermal cell layers. CONCLUSIONS: This is the first study to demonstrate a regulation of ECM1 expression in human skin by age and UV exposure. These data suggest that ECM1 expression may represent a cutaneous stress response to acute and chronic UV irradiation.     

Lipoid proteinosis: A case with distinct histopathological and radiological findings

Lipoid proteinosis is a rare inherited genodermatosis characterized by hyaline deposits in various tissues. Clinically, it manifests with cutaneous as well as extracutaneous features. Periodic acid‐Schiff (PAS)‐reactive hyaline deposits in the upper dermis, with localization around blood vessels and eccrine sweat glands, in particular, is the histopathological hallmark finding. On brain imaging, bilateral symmetrical temporal lobe calcifications are considered to be pathognomonic of this disorder. We report a case of lipoid proteinosis in which hyaline deposits were present in the papillary and reticular dermis, without being seen at the periphery of eccrine sweat glands, along with dystrophic calcification. Magnetic resonance imaging (MRI) of brain revealed hydrocephalus, subependymal heterotropia and absent splenium of corpus callosum with no evidence of temporal lobe calcification. Thus, our case highlights the inherent diverse nature of lipoid proteinosis.     

中国5家系类脂蛋白沉积症临床和遗传特点分析

目的：了解中国人群中类脂蛋白沉积症(LP)的临床表型和遗传学特点。方法：描述了我院确诊的一LP家系中患者的临床表型和遗传特点，并综合20多年来国内文献报道的LP家系进行比较分析。结果：(1)LP在家系中的传递符合常染色体隐性遗传方式；(2)表型特点为患者多在2岁内发病，声音嘶哑、眼睑串珠状半透明丘疹，在每个患者均出现；一些少见的表现，如颅内钙化灶仅在家系1中出现，复发性腮腺炎或扁桃体炎仅在家系1和家系5中出现；6例患者健康状况不受该病影响，家系1中的先证者在18岁时曾出现呼吸困难；(3)多不伴发其他遗传病和系统疾病；(4)患者临床表现有一定程度的相似性，但严重程度有很大差异，既使在同一家系中也如此。结论：LP是一种罕见的常染色体隐性遗传病，中国人群中其致病基因的突变频率很低；LP临床表型相似，但不同患者表现度存在较大差异。     

A failure of mucocutaneous lymphangiogenesis may underlie the clinical features of lipoid proteinosis

Lipoid proteinosis (LiP) (OMIM 247100) is a rare autosomal recessive disease caused by loss of function mutations in the extracellular matrix protein 1 gene, ECM1, on chromosome 1q21. LiP is characterized clinically by hoarseness in early infancy, followed by waxy papules and plaques on the face and body along with pox-like and acneiform scars. We studied a 20-year-old Japanese woman with LiP. She was born of consanguineous parents. Biopsy specimens obtained from a nodule on the elbow were used for histopathology, immunohistology and electron microscopy. Exons 6 and 7 of ECM1 were amplified by polymerase chain reaction (PCR) from genomic DNA from the proband, her parents, her brother and an unrelated person. PCR products were sequenced to detect the mutation. Histopathological examination revealed an irregular mass of calcium beneath deposits of a hyaline material in the dermis. Immunofluorescence double staining showed that the CD31-positive microvascular density was increased but that staining for the lymphatic-specific hyaluronan receptor LYVE-1 was drastically diminished in lesional compared with nonlesional skin of the patient and with normal skin. Electron microscopy revealed marked concentric reduplication of basal laminae not only around blood vessels but also around solitary dermal cells positive for Weibel-Palade bodies scattered in the hyaline material. Sequencing of the PCR products revealed a homozygous frameshift mutation, 507delT, in exon 6. This led to a premature stop codon 23 bp downstream. The results of immunopathological and ultrastructural characterization suggest that a failure of mucocutaneous lymphangiogenesis may underlie the clinical features of LiP. Identification of mutation 507delT in a Japanese patient with LiP further supports the thesis that this mutation represents a recurrent mutation in ECM1 in patients with LiP. To our knowledge, this case represents the first report of calcinosis cutis occurring in LiP.     

Functional redundancy of extracellular matrix protein 1 in epidermal differentiation

BACKGROUND: Extracellular matrix protein 1 (ECM1) is a secreted protein expressed in skin. Its dermatological relevance has been highlighted by the discovery of loss-of-function mutations in ECM1 in patients with lipoid proteinosis (LiP). OBJECTIVES: To determine the role of ECM1 in epidermal differentiation by examining gene and protein expression of epidermal differentiation markers in individuals with LiP and histological assessment of transgenic mouse skin that overexpresses Ecm1a in basal or suprabasal epidermis. METHODS: Subconfluent, confluent and postconfluent LiP and control keratinocyte cultures were analysed by Northern and Western blotting for differences in expression of differentiation markers. Expression of these markers was analysed in skin of patients with LiP by immunohistochemistry. To study effects of Ecm1 overexpression on epidermal differentiation, transgenic mice were generated under control of either a keratin 14 or an involucrin promoter. RESULTS: No differential expression of the different markers analysed was observed in LiP keratinocytes compared with controls. No histological differences were found in Ecm1-overexpressing mouse skin compared with wild-type. CONCLUSIONS: Absence of ECM1 does not lead to differences in epidermal differentiation. Moreover, overexpression of Ecm1a in vivo does not exert dramatic effects on epidermal structure. Collectively, these findings suggest no role of ECM1 in epidermal differentiation.     

类脂蛋白沉积症一家系调查及基因突变检测

【摘要】 目的 报道1例来自山东的类脂蛋白沉积症家系,研究其家系成员的细胞外基质蛋白（ECM1）基因突变。 方法 类脂蛋白沉积症家系3代8名成员,有2例患者,分别为先证者（Ⅲ1）及其母亲（Ⅱ2）,均表现为睑缘丘疹、舌系带增厚变短及声音嘶哑。间接喉镜检查显示声带浸润增厚。睑缘及喉部黏膜组织病理检查均提示真皮透明蛋白样物质沉积,PAS染色强阳性,淀粉酶染色阴性,病理诊断符合类脂蛋白沉积症。采用DNA直接测序检测家系8例成员ECM1基因,巢式PCR琼脂糖凝胶电泳对患者的ECM1编码区进行基因突变分析。取100例正常汉族人基因组DNA样品做对照。 结果 2例患者均为遗传复合体,先证者母亲（Ⅱ2）ECM1的两个等位基因分别存在3个错义突变（p.P169T , p.A44T,p.R392W）。先证者除了从其母亲遗传来的一个错义突变外（p.P169T）,还有从其父亲（Ⅱ1）遗传来的一个同义突变（c.879G > A）,这个突变产生一个潜在的剪切受体位点“AG”,巢式PCR琼脂糖凝胶电泳结果和PCR产物测序结果证实,该同义突变导致ECM1基因的剪切发生改变。 结论 本类脂蛋白沉积症家系存在新的ECM1基因同义突变导致的剪切突变。     

Lipoid proteinosis presenting with an unusual nonsense Q32X mutation in exon 2 of the extracellular matrix protein 1 gene

Lipoid proteinosis (LP) is a rare disorder characterized by extensive hyaline‐like deposits on the skin, mucous membranes and various internal organs with varying clinical manifestations. The disorder has been recently shown to result from loss‐of‐function mutations in the extracellular matrix protein 1 gene (ECM1) on 1Q21. The two cases reported here had typical clinical and histological features consistent with LP. Direct sequencing of amplified DNA from the second patient showed a single nucleotide substitution (C > T) at nucleotide 94 within exon 2 of the ECM1 gene, nonsense mutation Q32X. This is the second case reported of LP with involvement of exon 2 of ECM1.     

Clinical and molecular characterization of lipoid proteinosis in Namaqualand, South Africa

BACKGROUND: Lipoid proteinosis (LiP) is a rare autosomal recessive disorder characterized by a hoarse voice, warty skin infiltration and scarring. Mutations within the extracellular matrix protein 1 (ECM1) gene cause LiP. Since the early 1970s it has been recognized that South Africa has one of the largest groups of LiP patients worldwide, suggesting a probable founder effect. As LiP patients present with considerable clinical variability, this group of patients offers a unique opportunity for genotype-phenotype correlation. OBJECTIVES: To assess the clinical features and the molecular basis of LiP in patients from the Namaqualand area of the Northern Cape province of South Africa and to examine molecular evidence for a founder effect. SUBJECTS AND METHODS: The LiP patient cohort consisted of 29 Coloured patients from Namaqualand and a further seven Caucasoid patients from other areas of South Africa. The control group included 100 healthy geographically and ethnically matched individuals from Namaqualand. Samples were collected after informed consent and with ethics committee approval from the University of the Witwatersrand. LiP patients were examined clinically and a structured recording sheet was completed. A brief neurological evaluation was also performed. The LiP founder effect was investigated at the molecular level by ECM1 mutation detection and haplotype analysis. RESULTS: The most consistent clinical signs for a diagnosis of LiP in this group were a hoarse voice and thickened sublingual frenulum leading to restricted tongue movement. Homozygosity for a nonsense mutation in exon 7 of the ECM1 gene, Q276X, was identified in all patients (Coloured and Caucasoid). Despite this genetic homogeneity, considerable clinical variability in skin presentation and psychiatric involvement was observed. Haplotype analysis using markers from a 9.98-Mb region around the ECM1 locus confirmed the founder effect with a founder core haplotype, 19-Q276X-12 (ND1-ECM1-D1S2343), in all but four LiP-associated alleles (n = 58). A LiP carrier rate of 1 in 9 was observed among the 100 Namaqualand controls, predicting a LiP incidence of 1 in 324 in this community. CONCLUSIONS: Although several consistent clinical features in LiP patients homozygous for the Q276X mutation in the ECM1 gene were observed, there remains considerable clinical variability. This suggests the action of genetic and environmental modifiers of disease severity. Strong molecular evidence supports a single founder effect for the high prevalence of LiP in South Africans, both Coloured and Caucasoid.     

Cutaneous Neurofibroma Heterogeneity: Factors that Influence Tumor Burden in Neurofibromatosis Type 1

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