Hypophosphatasia. Review of 24 cases

Perinatal lethal hypophosphatasia; clinical, radiologic and morphologic findings

Clinical, radiographic and morphologic analysis of nineteen cases of perinatal (lethal) hypophosphatasia was performed. Three families each had two affected offspring. All of the patients had lethal short limb dwarfism with very soft calvaria. Other clinical findings included polyhydramnios, blue sclerae and spurs in the mid-portion of the forearms and lower legs. Considerable variability was found in the skeletal radiographs. In addition to the well known radiographic features such as generalized decrease in the size of ossified bones with some bones not ossified at all, other changes observed included: 1) marked variability in the amount of bone ossification; 2) variability between patients as to which bones were most severely affected; 3) unusually dense, round, flattened, butterfly shaped; and sagittally clefted vertebral bodies; 4) variability in femoral shape including "chromosome" like, "campomelic" like, and shortening with or without metaphyseal cupping or irregularities; 5) osteochondral projections (Bowdler spurs) of the midshaft of the fibula and ulna. Recognition of the marked clinical and radiographic variability in this autosomal recessive lethal skeletal dysplasia is important for accurate genetic counseling and prenatal diagnosis.

Dental aspects of hypophosphatasia: a case report, family study, and literature review

The classic oral features of hypophosphatasia, namely, premature tooth loss and large pulp spaces, were found in a young adult woman with bone and joint pains. A study of 22 family members revealed several with dental abnormalities such as abnormal enamel, dentin, or cementum formation, decreased mandibular bone density, and abnormally large pulp spaces. Only the propositus' sister fulfilled the biochemical criteria for hypophosphatasia. Biochemical examination of an extracted tooth from this sister showed phosphate and alkaline phosphatase values that were 7 to 10 times lower than normal and reduced concentrations of the essential cofactors Zn++ and Co++. The spectrum of dental abnormalities is reviewed. This family study reveals that enamel hypoplasia, increased pulp spaces, and premature tooth loss are present not only in the deciduous but also in the permanent dentition. These findings should draw the dentist's attention to this condition.

Prominent transverse (Bowdler) bone spurs as a diagnostic clue in a case of neonatal hypophosphatasia without metaphyseal irregularity

Transverse midshaft spurs allowed a diagnosis of hypophosphatasia in a newborn infant without metaphyseal irregularity.

Vitamin D metabolism in hypophosphatasia

A 4-month-old boy with the infantile form of hypophosphatasia was followed for 9 months with measurements of serum calcium, phosphate, alkaline phosphatase and various vitamin D metabolites, together with urinary excretion of cyclic AMP. During the initial hypercalcemic stage the serum concentration of 25-hydroxyvitamin D was normal. Urinary cyclic AMP was low and the serum concentration of the dihydroxymetabolites of vitamin D were appropriate to the high serum calcium with low 1,25-(OH)2D and relatively high 24,25(OH)2D and 25,26(OH)2D levels. Due to restrictions of the vitamin D intake and lack of exposure to sun he developed vitamin D-deficiency rickets at 9 months of age with very low serum concentration of 25-hydroxyvitamin D and markedly increased urinary excretion of cyclic AMP. Following vitamin D treatment the serum level of 1,25(OH)2D showed a brisk rise to a considerably elevated value. Initially the serum concentration of alkaline phosphatase was well below the normal range, rose markedly during the stage of active rickets and returned to the characteristic low levels of hypophosphatasia with healing of the rickets.