Melodie Melbouci

I wipe down tables and aprons between usages, and escort patients to and from their rooms to x-ray.

Besides taking part in minor experiments in the skeletal dysplasia lab, I also author manuscripts pertaining to our area of research, the lysosomal storage disorders known by the name of Mucopolysaccharidoses (MPS).

I help out around the barn doing a variety of chores. I also assist the instructors who are a part of the therapeutic program with their students.

Morquio syndrome (mucopolysaccharidosis type IV [MPS IV]) is a rare lysosomal storage disease (LSD) that is inherited in an autosomal-recessive fashion. Morquio syndrome is classified into two types, Morquio A syndrome and Morquio B syndrome, based on a deficiency of different lysosomal enzymes—N-acetylgalactosamine-6-sulfate sulfatase (GALNS) and β-galactosidase, respectively. GALNS deficiency induces the accumulation of glycosaminoglycans (GAGs), keratan sulfate (KS), and chondroitin-6-sulfate (C6S) in multiple tissues, particularly bone, cartilage, heart valves, and cornea, while β-galactosidase deficiency induces the accumulation of only KS in those tissues.

Mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders that affect regulation of glycosaminoglycan (GAG) processing. In MPS, the lysosomes cannot efficiently break down GAGs, and the specific GAGs accumulated depend on the type of MPS. The level of impairment of breakdown varies between patients, making this one of the many factors that lead to a range of clinical presentations even in the same type of MPS. These clinical presentations usually involve skeletal dysplasia, in which the most common feature is bone growth impairment and successive short stature. Growth impairment occurs due to the deposition and retention of GAGs in bone and cartilage. The accumulation of GAGs in these tissues leads to progressive damage in cartilage that in turn reduces bone growth by destruction of the growth plate, incomplete ossification, and imbalance of growth. Imbalance of growth leads to various skeletal abnormalities including disproportionate dwarfism with short neck and trunk, prominent forehead, rigidity of joints, tracheal obstruction, kyphoscoliosis, pectus carinatum, platyspondyly, round-shaped vertebral bodies or beaking sign, underdeveloped acetabula, wide flared iliac, coxa valgus, flattered capital femoral epiphyses, and genu valgum. If left untreated, skeletal abnormalities including growth impairment result in a significant impact on these patients' quality of life and activity of daily living, leading to high morbidity and severe handicap. This review focuses on growth impairment in untreated patients with MPS. We comprehensively describe the growth abnormalities through height, weight, growth velocity, and BMI in each type of MPS and compare the status of growth with healthy age-matched controls. The timing, the degree, and the difference in growth impairment of each MPS are highlighted to understand the natural course of growth and to evaluate future therapeutic efficacy.