Bi-allelic CSF1R Mutations Cause Skeletal Dysplasia of Dysosteosclerosis-Pyle Disease Spectrum and Degenerative Encephalopathy with Brain Malformation.

Colony stimulating factor 1 receptor (CSF1R) plays key roles in regulating development and function of the monocyte/macrophage lineage, including microglia and osteoclasts. Mono-allelic mutations of CSF1R are known to cause hereditary diffuse leukoencephalopathy with spheroids (HDLS), an adult-onset progressive neurodegenerative disorder. Here, we report seven affected individuals from three unrelated families who had bi-allelic CSF1R mutations. In addition to early-onset HDLS-like neurological disorders, they had brain malformations and skeletal dysplasia compatible to dysosteosclerosis (DOS) or Pyle disease. We identified five CSF1R mutations that were homozygous or compound heterozygous in these affected individuals. Two of them were deep intronic mutations resulting in abnormal inclusion of intron sequences in the mRNA. Compared with Csf1r-null mice, the skeletal and neural phenotypes of the affected individuals appeared milder and variable, suggesting that at least one of the mutations in each affected individual is hypomorphic. Our results characterized a unique human skeletal phenotype caused by CSF1R deficiency and implied that bi-allelic CSF1R mutations cause a spectrum of neurological and skeletal disorders, probably depending on the residual CSF1R function.

Mucopolysaccharidosis type I, II and VI and response to enzyme replacement therapy: Results from a single-center case series study.

Mucopolysaccharidoses (MPS) types I, II and VI are associated with deficiencies in alpha-L-iduronidase, iduronate-2-sulfatase and N-acetylgalactosamine-4-sulfatase, respectively, and generally involve progressive and multi-systemic clinical manifestations. Enzyme replacement therapy (ERT) appears to be reasonably well tolerated. The aim of this study was to examine clinical and diagnostic findings of a series of pediatric and adult MPS patients, and assess the safety and efficacy of ERT in children and adults with MPS type I, II and VI. Pediatric and adult patients were treated weekly with 1 mg/kg recombinant human N-acetylgalactosamine-4-sulphatase (rhASB), 0.45 mg/kg alpha-L-iduronidase, or 0.5 mg/kg iduronate-2-sulfatase. Clinical and biochemical parameters with ERT were evaluated for a mean duration of 5 years. Mantel-Haenszel risk ratios and associated 95% confidence intervals (CIs) were calculated for rates of death among different types of enzyme replacement therapies (ERTs). Twenty-seven patients (mean ages ‒ pediatric: 6.8 years; adult: 29 years) were included. ERT was found to be consistently well tolerated and effective in attenuating symptoms, but did not prevent the progression of the disease or reduce mortality rates. Our findings demonstrated that early diagnosis and initiation of ERT are critical for improvements in patient-important outcomes and quality of life, although disease progression and mortality rates remain high.

Mucopolysaccharidosis type IVA: evidence of primary and secondary central nervous system involvement.

Mucopolysaccharidosis type IVA is a rare lysosomal storage disease caused by a deficiency of N-acetylgalactosamine 6-sulfatase. Studies usually focus on skeletal abnormalities and their consequences. This study explores the neurological manifestations in a cohort of mucopolysaccharidosis type IVA patients, with a detailed focus on brain and spinal magnetic resonance imaging (MRI) findings. We performed a cross-sectional study involving nine patients with a biochemical confirmation of mucopolysaccharidosis type IVA. The protocol consists of a comprehensive clinical examination and brain and spinal cord MRI analysis for all subjects. The mean age was 16.4 years (±5.7) and the mean onset of symptoms was 11.5 months (±6.3). Overall, cognition was spared in all but one patient and motor weakness was a constant finding in all patients. Deep sensation impairment was found in six patients. The brain MRIs showed non-specific white matter changes in two patients. Other abnormalities such as clival hypoplasia, basilar invagination, and arachnoid cists appeared in seven of the nine patients. Eight patients presented spinal cord compression, and in three of them, two spinal levels were compromised. Odontoid hypoplasia and degenerative features in the neuroaxis were present in all patients. Our experience with mucopolysaccharidosis type IVA patients supports the evidence of central nervous system involvement. We emphasize the importance of regular clinical assessments with complete MRI studies, as an attempt to detect the early signs of spinal cord compression. This evaluation may be especially important before surgical interventions, as occult lesions may become symptomatic and promote postoperative unfavorable outcomes.

New insights in mucopolysaccharidosis type VI: neurological perspective.

OBJECTIVE: Mucopolysaccharidosis type VI is a rare autosomal recessive storage disorder, caused by deficiency of arylsulfatase B. Data on neurological involvement in mucopolysaccharidosis type VI patients under enzyme-replacement therapy are limited. This study explores the neurological and magnetic resonance imaging findings in a sample of mucopolysaccharidosis type VI patients receiving enzyme-replacement therapy. METHODS: We performed a cross-sectional study including six patients with biochemical confirmation of mucopolysaccharidosis type VI and at least 105 consecutive weeks (two years) receiving intravenous enzyme-replacement therapy. The protocol included a comprehensive clinical examination, brain and spinal cord magnetic resonance imaging for all subjects. RESULTS: Overall, cognition was spared, while we found presence of hearing impairment, increasing in deep tendon reflexes and deep sensation reduction in three patients. In addition to the classical abnormalities related to other types of mucopolysaccharidosis, imaging studies demonstrated morphological changes in anatomy of middle cranial fossa and sella shape. Even in asymptomatic or mild compromised patients, spinal cord compression was found. In four patients we noticed atlantoaxial joint subluxation and three had cervical spinal stenosis. Degenerative processes involving vertebral column, including discal protrusion and axis abnormalities, were present in all patients. CONCLUSIONS: Neuroaxis involvement was a universal finding and neurological examination might not predict the severity of the disease in course. Image studies should not be performed according exclusively clinical parameters for these patients, once we have demonstrated that neurological involvement may be silent in these patients.