A Novel Homozygous GALNT3 Deletion in Hyperphosphatemic Familial Tumoral Calcinosis Presenting with Subcutaneous Calcifications and Raynaud’s Phenomenon in an Adult Patient: A Case Report
Year: 2026
Type: article
Study design: Case Report
Abstract: Introduction: Hyperphosphatemic familial tumoral calcinosis (HFTC) is a rare autosomal recessive disorder caused by pathogenic variants in the GALNT3, FGF23, or KL genes, leading to ectopic calcifications. It typically presents in childhood or adolescence with periarticular calcified masses; however, adult-onset cases are exceedingly rare. Case Presentation: We report a 54-year-old woman with a 5-year history of inflammatory bone pain, Raynaud’s phenomenon, and distal extremity calcifications. Laboratory evaluation revealed hyperphosphatemia, suppressed parathyroid hormone, elevated 1,25-dihydroxyvitamin D level, and increased tubular phosphate reabsorption, suggesting FGF23 deficiency or resistance. Genetic analysis identified a novel homozygous deletion of exons 8 and 9 in GALNT3. This variant was classified as likely pathogenic per ACMG criteria. The patient was treated with calcium-free phosphate binders, corticosteroids, NSAIDs, and dietary phosphate restriction, resulting in partial symptomatic improvement. Conclusion: This case represents one of the oldest patients with a genetically confirmed HFTC diagnosis and expands its known phenotypic spectrum. Multidisciplinary evaluation, including genetic counseling and screening of family members, is essential. Awareness of atypical presentations and consideration of genetic testing in patients with unexplained soft-tissue calcifications can facilitate timely diagnosis and management.
Source: Molecular Syndromology
DOI: 10.1159/000553258
Language: English
Subfield: Nephrology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7166653523