Gusdorf L, Mitcov M, Maradeix S, Cunat S, Martin L, Cribier B
Clinique dermatologique, hôpitaux universitaires de Strasbourg, 1, place de l'Hôpital, 67000 Strasbourg, France.
Clinique dermatologique, hôpitaux universitaires de Strasbourg, 1, place de l'Hôpital, 67000 Strasbourg, France.
Ann Dermatol Venereol. 2016 Apr;143(4):279-83. doi: 10.1016/j.annder.2015.11.010. Epub 2016 Mar 2.
Pseudoxanthoma elasticum (PXE)-like syndrome is characterized by the association of PXE and cutis laxa (CL) features with a deficiency of vitamin K-dependent clotting factors. It was first described in 1971 and was identified as a distinct genetic entity in 2007 with analysis of the GGCX (γ-glutamyl carboxylase) gene, which is involved in congenital deficiency in vitamin K-dependent clotting factors. Here we report a new case of this extremely rare syndrome.
A 23-year-old female patient was seen for the emergence of loose and redundant skin following extensive weight loss. She also presented a deficiency of vitamin K-dependent clotting factors. Physical examination revealed excessive, leathery skin folds in the axillary and neck regions. A skin biopsy revealed polymorphous and fragmented elastic fibers in the reticular dermis. These were mineralized, as was demonstrated by Von Kossa staining. The clinical features of CL associated with the histopathological features of PXE and vitamin K-dependent clotting factor deficiency led us to a diagnosis of PXE-like syndrome. A molecular study of the GGCX gene showed compound heterozygosity.
The GGCX gene is usually responsible for PXE-like syndrome. GGCX encodes a γ-glutamyl carboxylase necessary for activation of gla-proteins. Gla-proteins are involved both in coagulation factors in the liver and in the prevention of ectopic mineralization of soft tissues. Uncarboxylated forms of gla-proteins in fibroblast would thus enable mineralization and fragmentation of elastic fibers.
弹性假黄瘤（PXE）样综合征的特征是PXE和皮肤松弛症（CL）的特征与维生素K依赖性凝血因子缺乏相关。它于1971年首次被描述，并在2007年通过对GGCX（γ-谷氨酰羧化酶）基因的分析被确定为一种独特的遗传实体，该基因与先天性维生素K依赖性凝血因子缺乏有关。在此，我们报告了这一极其罕见综合征的一例新病例。
一名23岁女性患者因大量体重减轻后出现皮肤松弛和多余而前来就诊。她还存在维生素K依赖性凝血因子缺乏。体格检查发现腋窝和颈部区域有过多的皮革样皮肤褶皱。皮肤活检显示网状真皮中有多形性和断裂的弹性纤维。经冯·科萨染色证实这些纤维已矿化。CL的临床特征与PXE的组织病理学特征以及维生素K依赖性凝血因子缺乏导致我们诊断为PXE样综合征。对GGCX基因的分子研究显示为复合杂合性。
GGCX基因通常是PXE样综合征的病因。GGCX编码激活gla蛋白所必需的γ-谷氨酰羧化酶。gla蛋白既参与肝脏中的凝血因子，也参与预防软组织的异位矿化。因此，成纤维细胞中未羧化形式的gla蛋白会导致弹性纤维矿化和断裂。
