Hypophosphatasia (HPP) symptoms vary widely and depend on the type and stage of the condition. Symptoms can include deformed bones, shortened limbs, and tooth loss.

Hypophosphatasia symptoms can develop at any life stage and typically involve bone or teeth conditions. These symptoms can lead to severe clinical complications.

Symptoms vary in severity and appear in different ways, depending on age. HPP is often fatal for a fetus or newborn but can cause mild to severe symptoms or no symptoms at all in adults.

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Hypophosphatasia is a bone disorder caused by genetic mutations. It is a rare condition that can only be inherited.

People with HPP have a gene mutation that lowers tissue levels of an enzyme called alkaline phosphatase (ALP). Low levels of ALP block bones and teeth from taking up minerals such as calcium and phosphorus in a process called mineralization.

This causes abnormal development of the bones and teeth, which in turn results in a range of symptoms. These mainly include tooth loss and bones that easily break and deform.

There are seven recognized types of HPP, mainly classified by age:

  • Perinatal benign (at or before birth): This is a nonlethal type of HPP that affects fetuses and newborns.
  • Perinatal: This type of HPP occurs from birth to 4 weeks old.
  • Infantile: This type occurs from 4 weeks to 6 months old.
  • Childhood: This type of HPP occurs from 6 months to 18 years old.
  • Adult: This type occurs when a person is older than 18 years.
  • Odontohypophosphatasia: This type of HPP only affects a person’s teeth and can occur at any age.
  • Pseudohypophosphatasia: This type of HPP shares many HPP symptoms but without lowered ALP levels.

People with different types of HPP share many of the same symptoms. However, symptoms can also vary between each person.

Some people with HPP may have no symptoms. Symptoms can also vary markedly between members of the same family with HPP.

HPP symptoms tend to be less severe if they first appear in adulthood. Later forms of HPP from childhood onward are not usually fatal.

Perinatal and infant symptoms

Symptoms of perinatal and infant HPP include:

As infants with HPP grow, they may experience delayed growth. Infants with HPP may also experience breathing and feeding problems.

Childhood symptoms

Symptoms of childhood HPP vary but may include:

Adult symptoms

Adults with HPP often have mild symptoms but can develop disabilities due to bone and muscular problems from the condition.

Symptoms of HPP in adults include:

Short stature, short limbs, or other skeletal abnormalities may also occur. Stress fractures are especially common in the feet. Premature tooth loss often occurs in patients with otherwise good health.

Other types

Perinatal benign HPP symptoms include shortening or bowing of limbs in the womb, but this can show spontaneous improvement. Perinatal benign HPP is not usually life threatening.

People with odontohypophosphatasia will experience early tooth loss but no other symptoms.

Less common HPP symptoms include:

  • seizures
  • kidney problems (nephrocalcinosis)
  • overgrowth of cranial structures
  • delays in developing motor skills
  • calcium deposits in the eyes
  • delayed bone healing
  • damage to tendons or ligaments between bones

Types of HPP that occur earlier in life have higher risks of complications. These include seizures and breathing problems caused by rib cage defects.

Complications from HPP in adults can impact a person’s quality of life. Studies have found that people with HPP may experience the following:

  • bone pain
  • altered gait
  • muscle fractures
  • a need to use mobility devices
  • a need for orthopedic and dental surgeries

People with HPP can also experience complications related to growth and physical development. These can include muscle, kidney, or breathing problems.

A person who suspects they or a loved one may have HPP should seek advice from a healthcare professional. HPP symptoms vary widely and can often be mistaken for other conditions.

A blood test that measures ALP helps to diagnose HPP. Healthcare professionals may also use genetic testing to confirm an HPP diagnosis.

People living with HPP, friends, family, and caregivers, can find support and further resources through charities, nonprofits, and government organizations.

Here are some examples:

  • Soft bones: This nonprofit U.S.-based advocacy group for patients, families, and caregivers of people with HPP provides resources, training, and more.
  • National Organization for Rare Disorders (NORD): NORD is a patient advocacy organization that provides information and resources for people with rare conditions.
  • The Magic Foundation: This nonprofit charitable organization provides support services for families of children diagnosed with chronic conditions that affect a child’s growth.

HPP symptoms can vary widely. The severity of symptoms ranges from mild in adults to life threatening in infants.

Since symptoms can be mistaken for other conditions, it is important to seek professional medical advice if you or a loved one suspect symptoms may be HPP.

Healthcare professionals may recommend a range of treatments and therapies to address the symptoms of HPP.