ESPE Abstracts

Introduction: Metaphyseal dysplasia, Spahr type(MDST) is an autosomal recessive primary skeletal dysplasia characterized by postnatal short stature, progressive bowing deformity, waddling gait, with an incidence of <1/1 million. MDST is caused by mutations in Matrix metallopeptidase 13(MMP13) gene. The MMP13 plays a role in the degradation of extracellular matrix proteins. It is required for embryonic bone development and ossification. It may be involved in the cartilage life cycle and pathophysiology of osteoarthritis. MMP13 mutations are cause of Spondyloepimetaphyseal Dysplasia, Missouri type, Metaphyseal Anadysplasia1 and Metaphyseal Dysplasia, Spahr type. Here we present 12-year follow-up of a patient with MDST to reinforce our experience in approaching metaphyseal dysplasias and understanding of diseases in this spectrum.

Case: A two-year-old girl was referred for short stature. She was born with normal height, from consanguineous parents with normal height, at term after IVF pregnancy, weighing 3000grams, as a triplet. Her paternal cousins, a girl and a boy, had rhizomelic short stature. Her developmental milestones were on time. Her weight, height, BMI and head circumference were 13,1 kg(0,76 SD), 79,3 cm(-2,18 SD), 20.9 kg/m2(2,85 SD) and 48 cm(-0,16 SD) respectively. Upper to lower segment ratio was 1,54 and she had rhizomelic shortening of limbs. Skeletal survey revealed reduced interpedicular distances of the lumbar vertebrae; rib ends and long bone distal metaphyseal cupping. Rickets was excluded. Homozygous c.673G>A(p.Gly225Ser) variant was detected in the MMP13 gene. On the 3,5 years of age metaphyseal flaring, O-Bain deformity and lumbar lordosis was determined; the bone age was found as 3 years. The puberty has started at the age of 9,5 years and menarche occurred at the age of 11 years. In the follow-up, vertebral rotoscoliosis, knee joint pains were observed and osteoarthritis was not detected. Metaphyseal cupping and flaring became indistinct and the bone age exceeded the chronological age over time. At the last control, she was 14 years old, bone age was 16 years of age, her height was 138,7 cm(-3,66 SD), BMI was 29,9 kg/m2(1,13 SD), head circumference 56 cm(0,6 SD), upper to lower segment ratio was 1,2.

Conclusion: Since the ACAN gene is associated with the pathophysiology of MDST, clinical features such as osteoarthritis and advanced bone age are common. We think that the long-term follow-up of this case contributes to our experience in the approach to metaphyseal dysplasias and the pathophysiological process.