目的 探讨PSAT1基因变异丝氨酸缺乏症的临床分型、遗传学基础及诊疗策略，提升临床对该病的识别能力。方法 回顾性收集1例以鱼鳞病合并周围神经病为表现的患儿临床资料，通过家系全外显子组测序、Sanger验证及蛋白质结构预测研究其遗传学病理机制，并随访其治疗结果。系统检索数据进行文献复习，总结其临床表型、基因变异特征、治疗反应及预后特点。结果 患儿女，12岁，2岁起出现全身皮肤干燥脱屑，7岁起进行性双下肢无力、足下垂，伴水平眼震。既往检查示血浆丝氨酸水平正常（233.29μmol/L、319.19μmol/L），家系全外显子组测序检出PSAT1基因新纯合变异c.697C>A（p.Q233K），ACMG评级为意义未明变异，Sanger验证显示父母均为携带者。予以患者口服L-丝氨酸（300 mg·kg^-1·d^-1）和甘氨酸（200 mg·kg^-1·d^-1）补充治疗，1周后皮肤干燥脱屑明显好转，13周后行走步态显著改善，可自主下蹲站起。文献复习共纳入5例轻型丝氨酸缺乏症，结合本例共6例，均为PSAT1基因变异。结论 丝氨酸缺乏症表型谱广泛，轻型以儿童期鱼鳞病合并青少年期周围神经病为核心表现，因血浆丝氨酸水平多正常或轻度降低极易漏诊。早期诊断与及时补充L-丝氨酸对改善预后至关重要，可避免不可逆神经损伤。对原因不明的鱼鳞病伴周围神经病变患者，应尽早行基因检测以明确诊断。

Objective To investigate the clinical classification, genetic basis, and diagnostic and treatment strategies for serine deficiency caused by PSAT1 gene variants, in order to improve clinical recognition of this disorder. Methods Clinical data were retrospectively collected from a pediatric patient presenting with ichthyosis complicated by peripheral neuropathy. Family-based whole exome sequencing, Sanger validation, and protein structure prediction were performed. Following identification of the causative gene, treatment and follow-up were conducted. A systematic literature review was also carried out to summarize the clinical phenotypes, genetic variant characteristics, treatment responses, and prognostic features. Results The patient was a 12-year-old female who developed dry, scaly skin across the body at 2 years of age. Since the age of 7 years, she experienced progressive weakness in both lower limbs, foot drop, and horizontal nystagmus. Previous examinations revealed normal plasma serine levels (233.29 μmol/L and 319.19 μmol/L). Family-based whole exome sequencing identified a novel homozygous PSAT1 gene variant, c.697C>A (p.Q233K), which was classified as a variant of uncertain significance according to ACMG guidelines. Sanger sequencing confirmed that both parents were carriers. The patient received oral supplementation with L-serine （300 mg·kg^-1·d^-1） and glycine （200 mg·kg^-1·d^-1）. After one week of treatment, the dry skin and desquamation improved significantly. After 13 weeks, gait showed marked improvement, and the patient was able to squat and stand up independently. A literature review identified five additional cases of mild serine deficiency. Including the present case, a total of six cases were identified, all of which carried PSAT1 gene variants. Conclusion The phenotypic spectrum of serine deficiency is broad, with the mild form characterized by childhood-onset ichthyosis and adolescent-onset peripheral neuropathy as core manifestations. Affected individuals often have normal or only mildly reduced plasma serine levels, making this condition highly prone to being missed. Early diagnosis and timely supplementation with L-serine are critical for improving prognosis and can prevent irreversible neurological damage. For patients presenting with unexplained ichthyosis accompanied by peripheral neuropathy, genetic testing should be pursued as early as possible to establish a definitive diagnosis.