Abstract:
Marked ligamentous hyperlaxity and muscle weakness associated with significant motor retardation were the main clinical deficits confused enormously with the diagnosis of myopathy. Misdiagnosis can lead to a long list of sophisticated and unnecessary investigations. Fifteen children were referred to our orthopaedic departments from different paediatricians because of diverse forms of skeletal abnormalities, all were given the wrong diagnosis of myopathy. No definitive diagnosis was made and all underwent a series of sophisticated neuro-muscular investigations in other institutes in favour of myopathy. We applied our methodology through the clinical and radiographic phenotypes followed by targeted genotypic confirmation. Four children were compatible with the diagnosis of progressive pseudorheumatoid chondrodyspalsia (PPRC). The genetic mutation was correlated with the WISP 3 gene actively expressed by articular chondrocytes and located on chromosome 6 . Klinefelter syndrome was the diagnosis in three boys. Karyotyping confirmed the 47, XXY (aneuploidy of Klinefelter syndrome). And eight children were finally diagnosed with Morquio syndrome (MPS type IV A) both showed missense mutations in the N-acetyl-6 sulfatase gene. The value of this presentation is fivefold; first, when myopathy was suspected, this was followed by a series of sophisticated investigations, none of which precisely defined the disorder. Second, hypotonia, ligamentous hyperlaxity and waddling gait are misleading presentations in favour of myopathy. Third, the progressive nature of arthropathy was the incentive for radiographic documentation to rule out myopathy and confirm the diagnosis of (PPRC). Fourth, the clinical and the radiographic phenotypes in Klinefelter syndrome (XXY) and in Morquio's syndrome are characteristic and somehow pathognomonic. Fifth, physicians caring for children should be capable of assessing the musculo-skeletal system in correlation with clinical and radiographic phenotypes.
