Crane Jonathan S., Paller Amy S.
Sampson Regional Med Ctr / Campbell Univ
Northwestern University, Dermatology
X-linked ichthyosis (MIM #308100), also known as steroid sulfatase (STS) deficiency and X-linked recessive ichthyosis, is a recessive, nonsyndromic genetic skin disorder. This condition is caused by a mutation or deletion in the gene, which is responsible for encoding the steroid sulfatase enzyme, causing the complete loss of steroid sulfatase enzyme activity. Although X-linked ichthyosis equally affects all ethnic groups and races worldwide, the condition predominantly affects males rather than females, as suggested by its name. With an incidence of 1 in 2500 to 1 in 6000 males, X-linked ichthyosis is the second most common type of ichthyosis, after ichthyosis vulgaris. X-linked ichthyosis was first recognized by Dr Wells and Dr Kerr in 1965. Approximately 15% to 20% of individuals with this condition manifest symptoms at birth, which continue to progress, whereas the rest usually develop symptoms over the following weeks. Affected patients can normally produce skin cells but cannot shed them correctly, leading to dry skin that accumulates in the form of polygonal scales. Initially, the symptoms are usually mild and advance to the development of large, polygonal, brownish scales. The extracutaneous features include asymptomatic punctate corneal opacities, cryptorchidism, and cognitive or behavioral disorders, such as attention-deficit hyperactivity disorder (ADHD). The deficiency of steroid sulfatase results in the accumulation of cholesterol sulfate and depletion of cholesterol levels, leading to an abnormal skin barrier and retention of corneocytes. Although scaling typically does not affect flexural surfaces, such as the popliteal and antecubital fossae, palms, soles, hair, and nails, the anterior surface of the lower extremities is typically the most affected. Unfortunately, a definitive treatment does not exist for X-linked ichthyosis; however, various options are available for long-term management. The primary treatment objectives involve reducing dryness, minimizing scale formation, and enhancing skin appearance without causing irritation.
X连锁鱼鳞病（MIM #308100），也称为类固醇硫酸酯酶（STS）缺乏症和X连锁隐性鱼鳞病，是一种隐性、非综合征性遗传性皮肤病。这种疾病是由基因的突变或缺失引起的，该基因负责编码类固醇硫酸酯酶，导致类固醇硫酸酯酶活性完全丧失。尽管X连锁鱼鳞病在全球所有种族和民族中均有同等影响，但正如其名称所示，该病主要影响男性而非女性。X连锁鱼鳞病的发病率为每2500至6000名男性中有1例，是仅次于寻常型鱼鳞病的第二常见鱼鳞病类型。X连锁鱼鳞病于1965年首次被韦尔斯博士和克尔博士发现。约15%至20%的该病患者在出生时即出现症状，并持续进展，而其余患者通常在接下来的几周内出现症状。受影响的患者通常能够产生皮肤细胞，但无法正常脱落，导致皮肤干燥并以多边形鳞屑的形式堆积。最初，症状通常较轻，随后发展为大的、多边形的、褐色鳞屑。皮肤外表现包括无症状的点状角膜混浊、隐睾症以及认知或行为障碍，如注意力缺陷多动障碍（ADHD）。类固醇硫酸酯酶的缺乏导致硫酸胆固醇的积累和胆固醇水平的消耗，从而导致皮肤屏障异常和角质形成细胞滞留。尽管鳞屑通常不影响屈侧表面，如腘窝和肘前窝、手掌、脚底、毛发和指甲，但下肢前表面通常受影响最严重。不幸的是，目前尚无针对X连锁鱼鳞病的确切治疗方法；然而，有多种长期管理的选择。主要治疗目标包括减少皮肤干燥、尽量减少鳞屑形成以及改善皮肤外观而不引起刺激。
