What is Hypophosphatasia (HPP)?

HPP is a rare, progressive, multisystemic, inherited metabolic disorder.

Hypophosphatasia (HPP) can look and feel like many things: fatigue, pain, broken bones. While these symptoms may seem disconnected, HPP could be behind them all.
An important factor your doctor can look for is persistently low alkaline phosphatase (ALP).

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How common is HPP?

The short answer:
HPP is a rare, but inherited disorder.

This means multiple people in the same family may have it. If you’ve been diagnosed with HPP or have symptoms, think about encouraging your loved ones to consider their medical history and talk to a doctor as well.

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Who gets HPP?

While HPP can impact both children and adults, it is an illness that may begin in utero or may present at any age. Symptoms may be different depending on certain life stages.


For adults (18 years or older) diagnosed with HPP, symptoms can range from mild to severe. At this life stage, HPP may be associated with a number of symptoms including chronic bone pain, softening bones, and poor dentition and gum disease.

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Explore HPP in Adults

Children and Teens

For those diagnosed with HPP as children (between the ages of 6 months and 18 years or older), symptoms can range widely. Some of the symptoms may include slow or stunted growth; difficulty doing the things other children or teenagers can do (like climbing stairs or riding a bike), broken bones, muscle pain, weakness, early tooth loss, and fatigue. Sometimes, HPP symptoms will improve on their own; other times, they can cause additional complications with age.

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Explore Childhood HPP


Occurring after birth but before the age of six months, infantile HPP is marked by low levels of ALP, poor bone formation, respiratory problems, and renal compromise, resulting in serious long-term complications.

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Explore infantile HPP

Unborn Babies

Perinatal HPP is often the most severe form of HPP and begins in utero or at birth. It is characterized by significant bone loss and needs to be identified quickly to take action.

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Explore infantile HPP
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What causes HPP?

HPP is caused by a defective Alkaline Phosphatase (ALPL) gene.

This makes it difficult for the body to create enough ALP enzyme to maintain adequate bone and teeth mineralization over time.

Learn about ALP

How does HPP affect the
body’s bones and organs?

HPP isn’t limited to broken bones and difficulty moving around. As a multisystemic condition, HPP can affect many areas of the body, causing pain, fatigue, and brain fog.

Select a system below* to see how it can be affected by HPP:

*not an exhaustive list

Skull and Brain

  • Early closure of the skull plates
  • Abnormal head shape
  • Seizures
  • Fatigue
  • Brain fog

A symptom most commonly seen in infants and young children.


  • Early loss of baby or adult teeth
  • Painless loss of the entire tooth with the root intact
  • Gum disease


  • Weak/brittle bones
  • Rickets
  • Frequent atypical bone fractures (thigh, feet, toes)
  • Bowed legs/knock knees
  • Slow-healing bone injuries
  • Persistent bone pain

Joints and Muscles

  • Muscle weakness
  • Persistent muscle/joint pain
  • Pseudogout (gout with calcium crystal deposits instead of urea crystal deposits)
  • Impaired mobility
  • Need for mobility aids


  • Slow-growing ribs
  • Underdeveloped ribs leading to chest deformity
  • Breathing complications
  • Increased risk of pneumonia

A symptom most commonly seen in infants and young children.


  • Calcium buildup in the kidneys
  • Kidney disease or kidney failure
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