Perinatal Hypophosphatasia
is expressed in utero and can result in stillbirth due to lack of mineral in the skeleton.

Infantile Hypophosphatasia
presents before 6 months of age. The observable symptoms can be poor feeding, inadequate weight gain and clinical features of rickets. The cranial sutures are wide and generally the skeletal manifestations are the most severe. The ability to crawl is slow as well as the walking which gives the appearance of a waddling gait. Usually, there is premature loss of many of the teeth before 5 years of age.

Childhood Hypophosphatasia
may show some of the above symptoms. Usually early loss of teeth (incisors) before age 5 and some later. There is delayed walking with the waddling gait, bowed legs or knock-knees -- often enlargement of the wrists, knees or ankles. There may be pain and stiffness with muscle weakness in the lower limbs.

Odontohypophosphatasia
shows signs of premature loss of teeth but no skeletal problems.

Pseudohypophosphatasia
is an extremely rare form. It is typical of subjects who have infantile hypophosphatasia, yet serum total ALP activity is consistently normal or increased.

Adult Hypophosphatasia
usually presents itself during middle age but many individuals remember a history of premature loss of teeth, slowness in walking with tiredness and pain in legs and feet. Stress fractures in feet, thighs or hips may develop. Many have early loss or extraction of their secondary teeth. Arthritis (pseudogout) occurs in some patients, also degeneration of articular cartilage. This form can be difficult to diagnose as sometimes the youthful years may be fairly normal -- one may not seek medical help until later in life.