What is Hyperphosphatasia with Impaired Intellectual Development Syndrome?
Hyperphosphatasia with Impaired Intellectual Development syndrome is characterized by increased levels of the enzyme alkaline phosphatase in the blood. Known as hyperphosphatase, it causes no known health issues but is often the first indication an individual has the syndrome.
The syndrome is characterized by intellectual disability, delayed psychomotor development, absent or very limited speech, and distinct facial features.
Syndrome Synonyms:
Mabry Syndrome; Glycosylphosphatifilinositol Biosynthesis Defect 2; GPIBD2
What gene change causes Hyperphosphatasia with Impaired Intellectual Development syndrome?
The syndrome is caused by mutations in the PIGV, PIGO, PIGY, PIGW, PGAP2 and PGAP3 genes. It is inherited in an autosomal recessive pattern.
Autosomal recessive inheritance means an affected individual receives one copy of a mutated gene from each of their parents, giving them two copies of a mutated gene. Parents, who carry only one copy of the gene mutation will not generally show any symptoms but have a 25% chance of passing the copies of the gene mutations onto each of their children.
What are the main symptoms of Hyperphosphatasia with Impaired Intellectual Development syndrome?
The main initial symptom of the syndrome may vary from mild to severe. Intellectual disability is a major syndrome, as is limited to zero speech development. Delayed motor skill development is also common with the syndrome.
Facial and physical characteristics include wide-set eyes, long eyelid openings, a broad nasal bridge, a rounded nose tip, a thin upper lip, and a downward-pointing mouth. Further physical features include underdeveloped fingernails and short bones at the end of fingers. Low muscle tone is a common symptom.
Other health conditions may include seizures with muscle rigidity, convulsions, and loss of consciousness. Some individuals suffer from digestive issues as well.
How is it diagnosed?
To find out if someone has a diagnosis of Hyperphosphatasia with impaired intellectual development syndrome, it is important to have a consultation and evaluation with a clinical genetic specialist. Specialists may also suggest specific genetic testing or other types of tests to help reach a diagnosis. FDNA’s AI technology can help speed up the diagnostic process by analyzing facial features and other health information.
