The highest incidence of hypophosphatasia has been reported in the Mennonite population in Manitoba, Canada where one in every 25 individuals are considered carriers and one in every 2,500 newborns exhibits severe disease. Hypophosphatasia is considered particularly rare in people of African ancestry in the U.S. Diagnosis
Dental findings
Hypophosphatasia is often discovered because of an early loss of deciduous (baby or primary) teeth with the root intact. Researchers have recently documented a positive correlation between dental abnormalities and clinical phenotype. Poor dentition is also noted in adults. Laboratory testing
The symptom that best characterizes hypophosphatasia is low serum activity of alkaline phosphatase enzyme (ALP). In general, lower levels of enzyme activity correlate with more severe symptoms. The decrease in ALP activity leads to an increase in pyridoxal 5’-phosphate (PLP), which is the major form of Vitamin B6, in the blood, although tissue levels of Vitamin B6 may be unremarkable and correlates with disease severity. Urinary inorganic pyrophosphate (PPi) levels are elevated in most hypophosphatasia patients and, although it remains only a research technique, this increase has been reported to accurately detect carriers of the disease. In addition, most patients have an increased level of urinary phosphoethanolamine (PEA) although some may not. PLP screening is preferred over PEA due to cost and sensitivity.Tests for serum tissue-non-specific ALP (sometimes referred to as TNSALP) levels are part of the standard comprehensive metabolic panel (CMP) that is used in routine exams, although bone-specific ALP testing may be indicative of disease severity.
Treatment
Epidemiology
Perlman syndrome is a rare disease with an estimated incidence of less than 1 in 1,000,000. As of 2008, fewer than 30 patients had ever been reported in the world literature. See also
Beckwith–Wiedemann syndrome
Multiple abnormalities
Renal cell carcinoma

References


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