Mucopolysaccharidosis type I (MPS I) is a rare lysosomal storage disease caused by biallelic mutations in IDUA, the gene coding for the lysosomal enzyme alpha L-iduronidase. Clinically MPS I is a chronic progressive multisystem disease typically presenting with coarse facial features, skeletal deformities, joint contractures, and multi-organ involvement. Hurler syndrome (MPS IH) represents the severe end of the spectrum of mucopolysaccharidosis type I and is characterized by central nervous system involvement leading to childhood dementia.

Here we report on a severe affected MPS IH patient who is homozygous for a splice site mutation (c.158 + 1G > A) in the IDUA gene. Further analyses revealed maternal uniparental disomy of chromosome 4 with partial isodisomy of the telomeric end of chromosome 4 (4.p16.3p15.2), representing an extraordinary mode of inheritance with a much lower re-occurrence risk for MPS I in the family.

黏多糖贮积症I型（MPS I）是由在双等位基因突变罕见的溶酶体贮积症IDUA，该基因编码溶酶体酶的α- L-艾杜糖苷酸酶。临床上MPS I是一种慢性进行性多系统疾病，通常表现为面部特征粗糙，骨骼畸形，关节挛缩和多器官受累。Hurler综合征（MPS IH）代表I型粘多糖贮积症的严重范围，其特征是中枢神经系统受累导致儿童痴呆。

在这里，我们严重影响MPS IH病人谁是纯合剪接位点突变在（c.158 + 1G> A）报告IDUA基因。进一步的分析表明，母亲的4号染色体单亲二体性与4号染色体的端粒端部的部分等位线（4.p16.3p15.2）代表了一种非同寻常的遗传方式，家庭中MPS I的复发风险更低。