Expansion of the Genetic and Phenotypic Spectrum of Hereditary Spastic Paraplegia Caused by ABHD16A Gene Variants: An Integrated Analysis Based on Novel Variants and Literature Review

qiang zhang¹Manling He²Shaoke Chen²Chuan Li²Xie Bobo²Qingxiu Zhao²Yiyun Huang²XIN FAN^2*

• ¹Department of Genetic and Metabolic Central Laboratory, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, China., Nanning, China
• ²Department of Pediatric, The Second Affiliated Hospital of Guangxi Medical University, Nanning, China

Background: Hereditary spastic paraplegia (HSP) is a clinically and genetically heterogeneous neurodegenerative disorder. Biallelic pathogenic variants in ABHD16A have recently been linked to a neurodevelopmental phenotype featuring early-onset spasticity and global developmental delay. Objective: To further define the clinical and genetic spectrum of ABHD16A-associated disease through the characterization of a novel pediatric case and an updated literature review. Methods: We evaluated a child presenting with global developmental delay and progressive spastic paraplegia. Whole-exome sequencing (WES) was performed, and candidate variants were validated by Sanger sequencing. Clinical features were documented prospectively, and a systematic review of published cases was conducted to assess phenotypic patterns and genotype–phenotype relationships. Results: Consistent with prior reports, the core features of ABHD16A-related disease include global developmental delay, intellectual disability, and spastic paraplegia, often with early onset. In our patient, tandem mass spectrometry revealed elevated long-chain acylcarnitines (C16, C18:1, C18:2)—a metabolic abnormality not previously described in this condition. WES identified two novel compound heterozygous frameshift variants in ABHD16A: c.119delA (p.His40Leufs49) and c.559_562del (p.Pro187Cysfs29), both confirmed by Sanger sequencing and classified as pathogenic (ACMG criteria: PVS1, PM2, PM3, PP1). Our literature review identified 17 additional individuals from 9 families, enabling a refined clinical delineation: most patients exhibited motor and speech delay, axial hypotonia evolving into spasticity, and variable degrees of cognitive impairment. Conclusions: To our knowledge, this is the first reported case of ABHD16A-related neurodevelopmental disorder in a Chinese patient. We provide a detailed phenotypic characterization and an updated review of the published literature to support clinical recognition and genetic diagnosis of this emerging condition.