Patient with a progressive arthropathy: a unique story. Attenuated forms of mucopolysacharidosis type I. Case report and review of the literature

Abstract

Mucopolysaccharidosis type I are lisosomal storage diseases that are caused by a mutation on the gene that encodes the lisosomal enzyme α-L-iduronidase necessary for the glycosaminoglycan heparan sulfate and dermatan sulfate catabolism. The inheritance is autosomal recessive, with a prevalence of 1 to 1,9 per 100.000 live births. It is of progressive and multisystemic nature. Three phenotypes of the diseases has been described, Hurler syndrome, Hurler-Scheie syndrome and Scheie syndrome, depending of the severity of the symptoms and the neurological impairment. There are not clinical parameters that differentiate one phenotype from the others. Therefore, currently it is accepted the difference between accentuated phenotypes and attenuated phenotypes taking into account the therapeutical options for each type. The coarse features onset in the attenuated phenotypes presents a heterogeneous display, this is the reason why it often goes unnoticed, contributing to its underdiagnoses. The arthropathy presented in most patients, is bilateral, symmetrical and universal, affecting to a greater or lesser extent to all joints, causing joint mobility restriction. These patients also present upper airway compromise, cardiac and ophthalmological involvement and risk of myelopathy, all these could lead to increased morbidity and mortality. Early diagnosis is very important, since enzyme replacement therapy with laronidase improves the non-neurological clinical manifestation and stabilizes the disease progression. We present a clinical case of a patient with a story of progressive joint mobility restriction, accompanied of decrease visual acuity due to corneal clouding, otorhinolaryngologic recurrent infections, developmental delay (short stature) and umbilical hernia surgery. Patient was diagnosed MPS I at 21 and started treatment with laronidase at 23 years old.