Delayed speech, hyperactivity, and coarse facies: Does Sanfilippo syndrome come to mind?

Mucopolysaccharidosis-Plus Syndrome: Is This a Type of Mucopolysaccharidosis or a Separate Kind of Metabolic Disease?

Several years ago, dozens of cases were described in patients with symptoms very similar to mucopolysaccharidosis (MPS). This new disease entity was described as mucopolysaccharidosis-plus syndrome (MPSPS). The name of the disease indicates that in addition to the typical symptoms of conventional MPS, patients develop other features such as congenital heart defects and kidney and hematopoietic system disorders. The symptoms are highly advanced, and patients usually do not survive past the second year of life. MPSPS is inherited in an autosomal recessive manner and is caused by a homozygous-specific mutation in the gene encoding the VPS33A protein. To date, it has been described in 41 patients. Patients with MPSPS exhibited excessive excretion of glycosaminoglycans (GAGs) in the urine and exceptionally high levels of heparan sulfate in the plasma, but the accumulation of substrates is not caused by a decrease in the activity of any lysosomal enzymes. Here, we discuss the pathomechanisms and symptoms of MPSPS, comparing them to those of MPS. Moreover, we asked the question whether MPSPS should be classified as a type of MPS or a separate disease, as contrary to 'classical' MPS types, despite GAG accumulation, no defects in lysosomal enzymes responsible for degradation of these compounds could be detected in MPSPS. The molecular mechanism of the appearance of GAG accumulation in MPSPS is suggested on the basis of results available in the literature.

Symptoms of Autism Spectrum Disorder (ASD) in Individuals with Mucopolysaccharide Disease Type III (Sanfilippo Syndrome): A Systematic Review

The prevalence of autism spectrum disorder (ASD) in many genetic disorders is well documented but not as yet in Mucopolysaccharidosis type III (MPS III). MPS III is a recessively inherited metabolic disorder and evidence suggests that symptoms of ASD present in MPS III. This systematic review examined the extant literature on the symptoms of ASD in MPS III and quality assessed a total of 16 studies. Results indicated that difficulties within speech, language and communication consistent with ASD were present in MPS III, whilst repetitive and restricted behaviours and interests were less widely reported. The presence of ASD-like symptoms can result in late diagnosis or misdiagnosis of MPS III and prevent opportunities for genetic counselling and the provision of treatments.