Possible adult-onset hypophosphatasia variant presenting as young-onset parkinsonism with limited levodopa responsiveness.

Authors

Biswamohan Mishra, Sunil Kumar Jena, Nikhilesh Pradhan, Manoj Kumar Nayak

Published in

BMJ case reports. Volume 19. Issue 8. Aug 17, 2026. Epub Aug 17, 2026.

Abstract

A woman in her late 40s presented with a 1 year history of progressive symmetrical rest tremor, bradykinesia, rigidity, hypophonia and postural instability (Movement Disorder Society-sponsored Revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) III 41) without musculoskeletal symptoms or family history. Routine investigations were unremarkable except low-normal serum alkaline phosphatase (41 U/L, range 35-104), mild anaemia and vitamin D insufficiency; brain MRI showed blooming in bilateral globus pallidi. Minimal to no improvement observed at 1 month on modest dopaminergic dosing (MDS-UPDRS III 38). Whole-exome sequencing identified a heterozygous pathogenic frameshift variant c.388del (p.Val130Cysfs*1) in ALPL (alkaline phosphatase, liver/bone/kidney) gene. In the absence of classical skeletal features and without substrate testing, this finding is suggestive of a possible mild adult hypophosphatasia phenotype. This case highlights a potential association between ALPL variants and parkinsonism and underscores the role of genetic testing in atypical presentations.

PMID:
42608077
Bibliographic data and abstract were imported from PubMed on 18 Aug 2026.

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