Guided growth may not be the best option for knee valgus deformity in adolescent patients with Morquio-A

Treatment of skeletal and non-skeletal alterations of Mucopolysaccharidosis type IVA by AAV-mediated gene therapy

Mucopolysaccharidosis type IVA (MPSIVA) or Morquio A disease, a lysosomal storage disorder, is caused by N-acetylgalactosamine-6-sulfate sulfatase (GALNS) deficiency, resulting in keratan sulfate (KS) and chondroitin-6-sulfate accumulation. Patients develop severe skeletal dysplasia, early cartilage deterioration and life-threatening heart and tracheal complications. There is no cure and enzyme replacement therapy cannot correct skeletal abnormalities. Here, using CRISPR/Cas9 technology, we generate the first MPSIVA rat model recapitulating all skeletal and non-skeletal alterations experienced by patients. Treatment of MPSIVA rats with adeno-associated viral vector serotype 9 encoding Galns (AAV9-Galns) results in widespread transduction of bones, cartilage and peripheral tissues. This led to long-term (1 year) increase of GALNS activity and whole-body correction of KS levels, thus preventing body size reduction and severe alterations of bones, teeth, joints, trachea and heart. This study demonstrates the potential of AAV9-Galns gene therapy to correct the disabling MPSIVA pathology, providing strong rationale for future clinical translation to MPSIVA patients.

Diagnosis of Morquio-A patients in Mexico: How far are we from prompt diagnosis?

Mucopolysaccharidosis IV A, better known as Morquio-A syndrome, is a rare condition with severe skeletal and multiorgan involvement. Sometimes is not easy to differentiate from other skeletal dysplasias. Prior to definitive diagnosis, patients have been delayed or misdiagnosis due to lack of knowledge of local physicians about this disease. The aim of this study is to compare the age of onset of clinical manifestations, age of diagnosis, as seen by the parent or primary caregiver and compare this age with other population reports worldwide. Self-administered questionnaires were conducted to the primary caregiver of confirmed patients, collecting information about the onset of symptoms, age, previous diagnoses and biological variables (age, gender, sex). Data from 50 patients, 23 men and 27 women was obtained. Mean age at definitive diagnosis was 5.6 years, age at onset of signs or symptoms was 4.14 years starting with pigeon chest deformity, valgus knees at 4.5 years, stiff hands and increasing mobility of wrists to the 5.8 years, followed by limitation to lift shoulders to 7.1 years. In 78% of patients the diagnosis was by a geneticist. First and subsequent observed clinical changes were orthopedic, starting as early as 4.4 years as noted by parents. Rise of suspicious may delay 16 months' average to definitive diagnosis based on other multi-systemic findings. The most frequent specialist aid in diagnosis is a clinical geneticist followed by orthopedic surgeon. The diagnosis of Morquio-A disease in Mexico is as early as reports from other centers.