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ArticleDocumenta ophthalmologica. Advances in ophthalmology2026

Alpha-mannosidosis due to a novel MAN2B1 truncating mutation in a Chinese patient: a new report and long-term follow-up.

Fengxia Yao, Yamei Li, Xing Wei, Weimin Zhang, Yunyu Zhou, Yue Liu, Xuan Zou, Ruifang Sui

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Article in Documenta ophthalmologica. Advances in ophthalmology, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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5 · Who and what money

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8 authors.

Fengxia Yao *The Laboratory of Clinical Genetics, Rare Disease Medical Center, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
Yamei Li *Department of Ophthalmology, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, No. 1, Shuai Fu Yuan, Beijing, 100730, China.
Xing WeiDepartment of Ophthalmology, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, No. 1, Shuai Fu Yuan, Beijing, 100730, China.
Weimin ZhangThe Laboratory of Clinical Genetics, Rare Disease Medical Center, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
Yunyu ZhouDepartment of Ophthalmology, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, No. 1, Shuai Fu Yuan, Beijing, 100730, China.
Yue LiuDepartment of Ophthalmology, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, No. 1, Shuai Fu Yuan, Beijing, 100730, China.
Xuan ZouDepartment of Ophthalmology, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, No. 1, Shuai Fu Yuan, Beijing, 100730, China. zouxuan@pumch.cn.
Ruifang SuiDepartment of Ophthalmology, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, No. 1, Shuai Fu Yuan, Beijing, 100730, China. hrfsui@163.com.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

purposeTo report a case of α-mannosidosis with intellectual, hearing impairment and progressive retinal degeneration, supported by ten years of ophthalmic follow-up, genetic testing, and leukocyte α-mannosidase enzymatic analysis.

methodsThe patient underwent serial ophthalmic examinations over a ten-year period, including best-corrected visual acuity (BCVA) testing, fundus photography, optical coherence tomography (OCT), and fundus autofluorescence (FAF), to monitor disease progression. Trio-based whole-exome sequencing (WES) was performed on the family. Variant confirmation was conducted via Sanger sequencing. To support the genetic findings, leukocyte α-mannosidase activity was measured using fresh peripheral blood samples.

resultsAt first presentation, BCVA was 20/50 OD and 20/40 OS. Over the next decade, vision progressively declined to 20/200 in both eyes. Fundus images showed granular pigment mottling in the posterior pole, and subsequent wide-angle imaging detected bone-spicule pigmentation deposits in peripheral retina. OCT demonstrated progressive retinal thinning, with loss of the ellipsoid zone. FAF revealed expanding areas of retinal atrophy. The patient has presented with bilateral sensorineural hearing loss, delayed speech development, persistent dysarthria, mild cognitive impairment, and coarse facial features since childhood. Genetic analysis identified a novel homozygous MAN2B1 mutation: c.1316_1327delinsTGATG (p.Ala439Valfs*36), inherited from consanguineous parents with the same heterozygous genotypes. The variant was classified as pathogenic based on ACMG criteria. The patient's leukocyte α-mannosidase activity was profoundly decreased, confirming the diagnosis.

conclusionsThis case highlights the progressive nature of retinal degeneration in α-mannosidosis and underscores the diagnostic value of leukocyte enzyme testing alongside genetic and ophthalmic assessments. Early recognition of ophthalmic signs, particularly in patients with syndromic features such as hearing loss and facial dysmorphism, is essential for timely diagnosis and intervention.

Indexed as

alpha-Mannosidasealpha-MannosidosisDNAMutationVisual AcuityDNA Mutational AnalysisEast Asian PeopleFemaleFluorescein AngiographyFollow-Up StudiesFundus OculiHumansMalePedigreeTomography, Optical Coherencealpha-MannosidaseDNAEnzyme activityMAN2B1 geneRetinal degenerationα-mannosidosis

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.