Study Evaluates Bone Health in Sanfilippo and Related Conditions
Findings indicate many patients have low levels of vitamin D
When assessing bone density in people with conditions like Sanfilippo syndrome, it is necessary to account for impaired growth, which is common in these patients, a new study highlights.
The results also indicate many people with Sanfilippo and related conditions have low levels of vitamin D, showing a need to monitor levels of this important nutrient.
“Evaluation of bone health in patients with mucopolysaccharidosis,” was published in the Journal of Bone and Mineral Metabolism.
Mucopolysaccharidoses (MPS) are a group of genetic disorders characterized by the toxic accumulation of molecules called glycosaminoglycans (GAGs) in cells. Sanfilippo, also called MPS III, is caused by the buildup of a GAG called heparan sulfate.
Research done in animal models has indicated MPS can cause problems with bone health. Though people with MPS often show abnormalities in physical development and impaired mobility — which can lead to problems with bone development — few studies have specifically examined bone health in people with MPS. A team led by scientists at Çukurova University, Turkey, conducted a study to learn more.
“Although bone and joint findings in different types of MPS are important components of the clinical presentation and have a direct effect on quality of life and prognosis, there are limited studies on this subject. … This study is the first single-center large data sharing on the subject in a large number of patients with different types of MPS,” they wrote.
The study included 126 MPS patients, 18 of whom had Sanfilippo syndrome. Levels of vitamin D, a nutrient important for maintaining healthy bones, were somewhat low (“insufficient”) in 30.2% of patients, and were very low to the point of deficiency in 28.6% of patients.
The researchers noted many MPS patients are immobile and may get reduced exposure to sunshine, which could in part explain the high rates of low vitamin D, which is synthesized in the skin using energy from sunlight.
“Based on this result, it was concluded that although patients with MPS are not among the risk groups defined for [vitamin D] prophylaxis, routine monitoring of [vitamin D] levels is required in these patients,” researchers said.
Based on comparisons with average values for Turkish children, 67.5% of the MPS patients had an abnormally short stature for their age, and 50% were underweight for their age. Short stature and low body weight were less common in Sanfilippo syndrome than in some of the other MPS types — of the 18 Sanfilippo patients, six had short stature and three had low weight.
Of the MPS patients, 45, all who had short stature for their age, underwent dual-energy X-ray absorptiometry (DXA), an assessment used to measure bone mineral density (BMD).
In initial assessments, most (60%) of these patients had abnormally low BMD, suggestive of weakened bones. However, after the researchers performed statistical analyses to account for patients’ reduced height and age, only one individual (2.2%) had a low BMD. The researchers noted vitamin D levels tended to be lower in patients with lower BMD, though differences were not statistically significant.
“This result reminded us once again that height, age, and gender maturation should also be taken into account when evaluating DXA to prevent unnecessary antiresorptive treatment in patients with MPS,” the researchers concluded.