Inheritance: autosomal recessive
Biochemical Defect: deficiency of lysyl hydroxylase (PLOD). This results in decreased hydroxylation of collagen.
Major criteria:
(1) generalized joint laxity
(2) severe muscle hypotonia at birth ("floppy" baby)
(3) scoliosis present at birth, progressive as the patient becomes older
(4) scleral fragility, with rupture of the ocular globe after minor trauma
Minor criteria:
(1) tissue fragility with atrophic scars
(2) easy bruisability
(3) arterial rupture
(4) Marfanoid body habitus
(5) microcornea
(6) osteopenia in bones
(7) family history in sibs or other first degree relatives
(8) inability to walk as a young adult
The presence of >= 3 major criteria in an infant is highly suggestive of the diagnosis.
Laboratory confirmation:
(1) total urinary hydroxylysyl pyridinoline and lysyl pyridinoline crosslinks after hydrolysis
(2) dermal hydroxylysine
(3) measurement of lysyl hydroxylase activity in fibroblasts (research)
(4) mutational analysis of PLOD gene (research)
