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Mabry syndrome
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Mabry syndrome

Mabry syndrome is a rare genetic condition characterized by intellectual disability, distinctive facial features, and elevated levels of the enzyme alkaline phosphatase in the blood.

Description

Mabry syndrome is characterized by intellectual disability, distinctive facial features, and hyperphosphatasia (increased levels of alkaline phosphatase in the blood). Intellectual disability is often moderate to severe, typically accompanied by delayed motor skills and little to no speech development.

Common features include:

  • Low muscle tone (hypotonia)
  • Recurrent seizures (epilepsy), often involving muscle rigidity and loss of consciousness
  • Distinctive facial features (e.g., wide-set eyes, long eyelid openings, downturned mouth corners)
  • Shortened bones at the ends of fingers (brachytelephalangy)
  • Underdeveloped fingernails
  • Digestive system abnormalities (e.g., anal stenosis, Hirschsprung disease)

Hyperphosphatasia usually begins within the first year of life. While enzyme levels can be up to 20 times higher than normal, this finding itself appears to cause no negative health effects and serves as a diagnostic marker.

Frequency

Mabry syndrome is a rare condition with an unknown prevalence; more than 20 cases have been described in scientific literature.

Causes

Mutations in the PIGV, PIGO, or PGAP2 genes cause Mabry syndrome. These genes are involved in the synthesis and remodeling of glycosylphosphosphatidylinositol (GPI) anchors. These anchors attach specific proteins, such as alkaline phosphatase, to the outer surface of the cell membrane. Mutations result in incomplete GPI anchors, causing proteins to be released from the cell rather than binding to the membrane, which leads to hyperphosphatasia and other symptoms.

Genes Associated with Mabry Syndrome

  • PIGV
  • PIGO
  • PGAP2

Inheritance

This condition is inherited in an autosomal recessive pattern. Both copies of the gene in each cell must have mutations to cause the disorder. Parents of an affected individual each carry one copy of the mutated gene but typically do not show signs or symptoms.

Other Names

  • Hyperphosphatasia with mental retardation syndrome
  • Hyperphosphatasia with seizures and neurologic deficit

Frequently Asked Questions

The elevated alkaline phosphatase itself is a diagnostic marker and does not cause direct harm, so specific treatment to lower the enzyme is not required. Management focuses on the associated clinical features (e.g., seizures, hypotonia) while monitoring the level as part of routine follow‑up.
Early intervention is crucial: enroll in physical therapy to address hypotonia and improve gross motor milestones, and occupational therapy for fine‑motor skills. Speech‑language pathology with augmentative‑and‑alternative communication (AAC) devices can facilitate language acquisition, especially when speech is limited. Consistent home practice and a low‑stress environment enhance progress.
Because Mabry syndrome is autosomal recessive, both parents are carriers. Offer carrier testing to confirm each partner’s status, discuss a 25 % recurrence risk for each pregnancy, and present options such as prenatal diagnostic testing (chorionic villus sampling or amniocentesis) or pre‑implantation genetic testing (PGT‑M) with IVF to select embryos without the pathogenic variants.
First‑line antiepileptic drugs such as levetiracetam or valproic acid are commonly effective; dosing may need adjustment because of variable metabolism. If seizures are refractory, consider adding a second agent (e.g., clobazam) or evaluating for ketogenic diet therapy under specialist supervision. Regular EEG monitoring helps guide medication changes.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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