Mucopolysaccharidosis (MPS) represents a group of rare inherited metabolic disorders characterized by abnormal accumulation of glycosaminoglycans (GAGs) due to deficiencies of lysosomal enzymes. Mucopolysaccharidosis type I (MPS I) is caused by biallelic pathogenic variants in the IDUA gene and is inherited in an autosomal recessive pattern. The IDUA gene is located on chromosome 4p16.3 and encodes the lysosomal enzyme α-L-iduronidase, which plays a critical role in the degradation of GAGs, particularly dermatan sulfate and heparan sulfate. Reduced or absent IDUA enzymatic activity leads to the progressive accumulation of undegraded substrates within lysosomes, resulting in multisystem organ involvement. Based on clinical severity, MPS I is traditionally classified into three phenotypic subtypes: the severe form (Hurler syndrome), the intermediate form (Hurler-Scheie syndrome), and the attenuated form (Scheie syndrome, MPS I-S). This report describes a 13-year-old female patient in whom compound heterozygous pathogenic variants in the IDUA gene were identified by genetic testing, and whose clinical manifestations were consistent with the MPS I-S. In addition to typical skeletal and joint abnormalities, the patient also presented with uterine developmental abnormality. Currently, there is no definitive evidence supporting a direct causal relationship between MPS I and uterine developmental abnormalities; however, this case suggests a potential association between MPS I and reproductive system developmental abnormalities. This case may help further expand the phenotypic spectrum of MPS I and enhance clinical awareness of its multisystem involvement.

Mucopolysaccharidosis type I (MPS I), is an autosomal recessive disorder caused by a deficiency in the enzyme α-L-iduronidase (IDUA), leading to the accumulation of glycosaminoglycans (GAGs) in tissues. Early diagnosis and treatment [i.e., bone marrow transplantation and/or enzyme replacement therapy (ERT) with laronidase] are essential to prevent irreversible damage. The long-term effectiveness of exclusive ERT has been primarily described in attenuated phenotypes, while only a few cases have been reported in severe phenotypes. This study is a retrospective analysis summarising the collective experience of disease progression in 48 patients with severe and attenuated MPS I who were treated exclusively with laronidase over a median of 10 years at the Lyon Reference Centre for Hereditary Metabolic Diseases in France. Patients were categorised by genotype and further stratified by age at treatment initiation. The study assessed the evolution of urinary excretion of GAGs, pulmonary function, cardiac involvement and evolution, height, cognitive impairment, functional status, orthopaedic and ear-nose-throat (ENT) procedures, sleep apnoea, and carpal tunnel syndrome. Descriptive statistical analysis methods were used. ERT reduced the GAGus levels by 88% in severe MPS I and by 71% in attenuated MPS I, of which 47% and 65% patients, respectively achieved normal age-related GAG levels at the last follow-up. ERT provided stable or consistent improvement in forced vital capacity, slowed progression of adverse cardiac course and improved auditory transmission in majority of the severe and attenuated patients. At the last follow-up, 84% attenuated patients had normal cognitive development. In alive Hurler patients, cognitive development was very heterogenous; however, 73% patients had a developmental quotient (DQ) ≥ 70. Laronidase was effective in improving statural growth of attenuated patients treated before 9 years of age. Early ERT and regular multidisciplinary management are effective in slowing disease progression in severe and attenuated patients with MPS I and helping to maintain autonomy in patients with attenuated MPS I, ensuring a better quality of life. Mucopolysaccharidosis type I (MPS I) is a progressive multisystem disorder with features ranging over a continuum of severity. While affected individuals have traditionally been classified as having one of three MPS I syndromes (Hurler syndrome, Hurler-Scheie syndrome, or Scheie syndrome), no easily measurable biochemical differences have been identified and the clinical findings overlap. Affected individuals are best described as having either a phenotype consistent with either severe (Hurler syndrome) or attenuated MPS I, a distinction that influences therapeutic options. Severe MPS I: Infants appear normal at birth. Typical early manifestations are nonspecific (e.g., umbilical or inguinal hernia, frequent upper respiratory tract infections before age 1 year). Coarsening of the facial features may not become apparent until after age one year. Gibbus deformity of the lower spine is common and often noted within the first year. Progressive skeletal dysplasia (dysostosis multiplex) involving all bones is universal, as is progressive arthropathy involving most joints. By age three years, linear growth decreases. Intellectual disability is progressive and profound but may not be readily apparent in the first year of life. Progressive cardiorespiratory involvement, hearing loss, and corneal clouding are common. Without treatment, death (typically from cardiorespiratory failure) usually occurs within the first ten years of life. Attenuated MPS I: Clinical onset is usually between ages three and ten years. The severity and rate of disease progression range from serious life-threatening complications leading to death in the second to third decade, to a normal life span complicated by significant disability from progressive joint manifestations and cardiorespiratory disease. While some individuals have no neurologic involvement and psychomotor development may be normal in early childhood, learning disabilities and psychiatric manifestations can be present later in life. Hearing loss, cardiac valvular disease, respiratory involvement, and corneal clouding are common. The diagnosis of MPS I is established in a proband with suggestive clinical and laboratory findings by: detection of deficient activity of the lysosomal enzyme α-L-iduronidase (IDUA) in combination with elevation of glycosaminoglycan levels; and/or identification of biallelic pathogenic variants in IDUA on molecular genetic testing. Identification of the causative IDUA variants plays an important role in the determination of phenotype. Treatment of manifestations: An essential component of management is the determination of whether the proband has severe or attenuated MPS I. This requires detailed clinical and laboratory assessment and can be challenging in very young individuals. Targeted therapies: Hematopoietic stem cell transplantation (HSCT) is considered the standard of care for children with severe MPS I. Outcome is significantly influenced by disease burden at the time of diagnosis (and thus, by the age of the individual). HSCT can improve cognitive outcomes, increase survival, improve growth, reduce facial coarseness and hepatosplenomegaly, improve hearing, prevent hydrocephalus, and alter the natural history of cardiac and respiratory symptomatology. HSCT has lesser effects on the skeletal and joint manifestations, corneal clouding, and cardiac involvement. HSCT alters the course of cognitive decline in children with severe MPS I; cognitive outcome is greatly influenced by the degree of cognitive impairment at the time of transplantation. Due to the morbidity and mortality associated with HSCT, it is currently recommended primarily for children with severe MPS I. Enzyme replacement therapy (ERT) with laronidase (Aldurazyme®), licensed for treatment of the non-CNS manifestations of MPS I, improves liver size, linear growth, and mobility and joint range of motion; slows progression of respiratory disease; and improves sleep apnea in persons with attenuated disease. The age of initiation of ERT influences the outcome. Supportive care: Infant learning programs/special education for developmental delay; physical therapy, orthopedic surgery as needed, joint replacement for progressive arthropathy, atlanto-occipital stabilization; spinal cord decompression for cervical myelopathy; cerebrospinal fluid shunting for hydrocephalus; early median nerve decompression for carpal tunnel syndrome based on nerve conduction studies before clinical manifestations develop; special attention to anesthetic risks; hats with visors/sunglasses to reduce glare, corneal transplantation for ophthalmologic involvement; cardiac valve replacement as needed and bacterial endocarditis prophylaxis for those with cardiac involvement; tonsillectomy and adenoidectomy for eustachian tube dysfunction and/or upper airway obstruction; ventilating tubes; hearing aids as needed; CPAP for sleep apnea; gastrointestinal management for diarrhea and constipation. Surveillance: Annual assessment by a team of physicians with knowledge of the multisystem nature of MPS I. Specialists and assessments: orthopedic surgery including annual assessment of median nerve conduction velocity; ophthalmology, cardiology (including echocardiography), respiratory with assessment of pulmonary function and sleep studies, audiology, and otolaryngology. Assessment for constipation and/or hernias as needed. Early and continuous monitoring of head growth in infants and children with imaging as needed; assessment for evidence of spinal cord compression by neurologic examination; developmental assessment annually; and psycho-educational assessment of children with attenuated disease prior to primary school entry. Evaluation of relatives at risk: Early diagnosis prior to significant disease manifestations is warranted in relatives at risk in order to initiate therapy as early in the course of disease as possible. MPS I is inherited in an autosomal recessive manner. At conception, each child of a couple in which both parents are heterozygous for a IDUA pathogenic variant has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. Carrier testing for at-risk relatives and prenatal testing for pregnancies at increased risk are possible if both disease-causing IDUA variants have been identified in the family.

Hurler-Scheie syndrome (MPS IH/S), also known as mucopolysaccharidosis type I-H/S (MPS IH/S), is a lysosomal storage disorder caused by deficiency of the enzyme alpha-L-iduronidase (IDUA) leading to the accumulation of glycosaminoglycans (GAGs) in various tissues, resulting in a wide range of symptoms affecting different organ systems. Postgenomic omics technologies offer the promise to understand the changes in proteome, phosphoproteome, and phosphorylation-based signaling in MPS IH/S. Accordingly, we report here a large dataset and the proteomic and phosphoproteomic analyses of fibroblasts derived from patients with MPS IH/S (n = 8) and healthy individuals (n = 8). We found that protein levels of key lysosomal enzymes such as cathepsin D, prosaposin, arylsulfatases (arylsulfatase A and arylsulfatase B), and IDUA were downregulated. We identified 16,693 unique phosphopeptides, corresponding to 4,605 proteins, in patients with MPS IH/S. We found that proteins related to the cell cycle, mitotic spindle assembly, apoptosis, and cytoskeletal organization were differentially phosphorylated in MPS IH/S. We identified 12 kinases that were differentially phosphorylated, including hyperphosphorylation of cyclin-dependent kinases 1 and 2, hypophosphorylation of myosin light chain kinase, and calcium/calmodulin-dependent protein kinases. Taken together, the findings of the present study indicate significant alterations in proteins involved in cytoskeletal changes, cellular dysfunction, and apoptosis. These new observations significantly contribute to the current understanding of the pathophysiology of MPS IH/S specifically, and the molecular mechanisms involved in the storage of GAGs in MPS more generally. Further translational clinical omics studies are called for to pave the way for diagnostics and therapeutics innovation for patients with MPS IH/S.

Hurler syndrome, also known as mucopolysaccharidoses type I, is a rare autosomal recessive lysosomal storage disorder with decreased activities of α-L iduronidase, resulting in the accumulation of glycosaminoglycans (GAGs) within various tissues. The authors presented a case report of a 15-year-old male who presented with a lower respiratory tract infection and was admitted to the pediatrics department with a history of facial dysmorphism, skeletal abnormalities, and corneal clouding and below-normal cognitive function which is consistent with the Hurler-Scheie syndrome. Skeletal abnormalities include inverted j-shaped sella turcica, bullet-shaped phalanges, thoracolumbar kyphosis, and acetabular dysplasia. Mucopolysaccharidosis I is classically divided into three syndromes, that is, Hurler syndrome (the severe form), Hurler-Scheie syndrome (the intermediate form), and Scheie syndrome (the attenuated form). Most of a doctor's first diagnosis is based on their observation of the signs and symptoms. Early disease diagnosis, genetic counseling, and regular follow-up with recent treatment modalities can reduce mortality significantly and improve the child's health status.

Mucopolysaccharidoses (MPSs) are inherited metabolic diseases characterized by the deficiency of lysosomal enzymes and the accumulation of glycosaminoglycans in various organs, including the heart. In particular, aortic valve disease causes high morbidity and mortality rates, and sometimes requires surgical aortic valve replacement (SAVR) at a young age. Although transcatheter aortic valve replacement (TAVR) for severe aortic stenosis (AS) in surgical high-risk patients is a well-established treatment, there are few reports of TAVR in MPS and medium- and long-term outcomes are not known. We present a case of severe AS in a MPS patient with high risk for SAVR who was successfully treated with TAVR and has shown a fine medium-term result. A 40-year-old woman with MPS type I-HS (Hurler-Scheie syndrome) receiving enzyme replacement therapy as a systemic treatment had complained of syncope and worsening dyspnea, and she was diagnosed with severe AS. The patient had a history of temporary tracheotomy because of the difficulty of endotracheal intubation. Considering risk for general anesthesia, TAVR was performed under local anesthesia. She has improved symptoms for one-and-a-half years. TAVR for severe AS in MPS would be an alternative option for surgical high-risk patients and can demonstrate preferable medium-term outcomes combined with systemic therapies. Mucopolysaccharidoses (MPSs) are metabolic diseases affecting various organs. The MPS patients requiring surgical aortic valve replacement (SAVR) for severe aortic stenosis (AS) often have a high surgical risk. However, in MPS, transcatheter aortic valve replacement (TAVR) could be an alternative procedure to SAVR. We report a MPS patient treated with TAVR showing a preferable medium-term outcome. We suggest that TAVR for severe AS in MPS is an acceptable treatment option.