[Screening of high risk children for lysosomal storage diseases and analysis of disease spectrum].

<b>Objective:</b> To screen high risk children for lysosomal storage diseases (LSD) in southern China and analyze the spectrum characteristics of LSD in this region. <b>Methods:</b> A cross-sectional study was conducted. A total of 7 435 children at high risk of LSD were screened at Guangzhou Women and Children's Medical Center, Guangzhou Medical University from January 2009 to December 2024. The activities of 22 lysosomal enzymes from peripheral blood leukocytes or plasma were measured by fluorescence or colorimetric assays with synthetic substrates to screen for 24 LSD subtypes. <b>Results:</b> Among the 7 435 high risk children, 759 children were diagnosed with LSD (10.2%). The diagnosed cases included 506 males and 253 females, with an age at diagnosis of 3.0 (2.5, 5.5) years. The common disease types were mucopolysaccharidosis (MPS) (390 cases (51.4%)), sphingolipidoses (269 cases (35.4%)), glycogen storage disease (62 cases (8.2%)), and mucolipidosis types Ⅱ and Ⅲ (29 cases (3.8%)). Among the positive cases, 21 disease subtypes were identified. The 5 frequent subtypes, in descending order, were MPS type Ⅱ (197 cases (26.0%)), Gaucher disease (111 cases (14.6%)), MPS type ⅣA (87 cases (11.5%)), glycogen storage disease type Ⅱ (62 cases (8.2%)), and metachromatic leukodystrophy (MLD) (49 cases (6.5%)). The rarest subtypes were mannosidosis, multiple sulfatase deficiency and Wolman disease, each with 1 case (0.1%). <b>Conclusions:</b> Enzyme activity screening is essential for diagnosing high risk children with LSD. In Southern China, the most common LSD subtypes are MPS Ⅱ, Gaucher disease, MPS ⅣA, glycogen storage disease type Ⅱ, and MLD, while mannosidosis, multiple sulfatase deficiency and Wolman disease are the rarest.