European Journal of Pediatrics

, Volume 159, Issue 5, pp 375–379 | Cite as

Severe hypercalcaemia and respiratory insufficiency associated with infantile hypophosphatasia caused by two novel mutations of the tissue-nonspecific alkaline phosphatase gene

  • Hiroshi Mochizuki
  • Mariko Saito
  • Toshimi Michigami
  • Hirofumi Ohashi
  • Naoya Koda
  • Shuichi Yamaguchi
  • Keiichi Ozono
ORIGINAL PAPER

Abstract

We report the case of a male patient with infantile hypophosphatasia associated with severe hypercalcaemia and mild respiratory insufficiency. At the age of 2 months, severe hypercalcaemia, low levels of serum alkaline phosphatase activity, and elevated urinary excretion of calcium and phosphoethanolamine were noted. Radiological findings showed generalized osteopenia and disturbed and irregular ossification of the metaphyses. Their involvement had spontaneously improved at the age of 6 months. A genetic study revealed that the tissue-nonspecific alkaline phosphatase gene of the patient had two novel mutations, K207E and G409C, derived from the mother and father, respectively. A reconsitution experiment revealed that both mutant gene products had low but significant enzymatic activity.

Conclusion The detection of tissue-nonspecific alkaline phosphatase gene mutations and expression studies to determine the enzymatic activity of mutant gene products was useful for assessing the clinical course of this patient with hypophosphatasia.

Key words Infantile hypophosphatasia Hypercalcaemia Respiratory insufficiency Alkaline phosphatase TNSALP gene 

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Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • Hiroshi Mochizuki
    • 1
  • Mariko Saito
    • 2
  • Toshimi Michigami
    • 2
  • Hirofumi Ohashi
    • 3
  • Naoya Koda
    • 1
  • Shuichi Yamaguchi
    • 1
  • Keiichi Ozono
    • 2
  1. 1.Division of Endocrinology and Metabolism, Saitama Children's Medical Centre, 2100 Magome, Iwatsuki, Saitama 339-8551, Japan e-mail: h-mochi@zb3.so-net.ne.jp Tel.: +81-48-7581811; Fax: +81-48-7581818JP
  2. 2.Department of Environmental Medicine, Osaka Medical Centre and Research Institute for Maternal and Child Health, Izumi, Osaka 594-1101, JapanJP
  3. 3.Division of Medical Genetics, Saitama Children's Medical Centre, Iwatsuki, Saitama 339-8551, JapanJP

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