Rosario Casalone

Bio: Rosario Casalone is an academic researcher. The author has an hindex of 1, co-authored 1 publications receiving 22 citations.

Optimizing the Molecular Diagnosis of GALNS: Novel Methods to Define and Characterize Morquio A Syndrome-Associated Mutations

Abstract: Morquio A syndrome (MPS IVA) is a systemic lysosomal storage disorder caused by the deficiency of N-acetylgalactosamine-6-sulfatase (GALNS), encoded by the GALNS gene. We studied 37 MPS IV A patients and defined genotype-phenotype correlations based on clinical data, biochemical assays, molecular analyses, and in silico structural analyses of associated mutations. We found that standard sequencing procedures, albeit identifying 14 novel small GALNS genetic lesions, failed to characterize the second disease-causing mutation in the 16% of the patients' cohort. To address this drawback and uncover potential gross GALNS rearrangements, we developed molecular procedures (CNV [copy-number variation] assays, QF-PCRs [quantitative fluorescent-PCRs]), endorsed by CGH-arrays. Using this approach, we characterized two new large deletions and their corresponding breakpoints. Both deletions were heterozygous and included the first exon of the PIEZO1 gene, which is associated with dehydrated hereditary stomatocitosis, an autosomal-dominant syndrome. In addition, we characterized the new GALNS intronic lesion c.245-11C>G causing m-RNA defects, although identified outside the GT/AG splice pair. We estimated the occurrence of the disease in the Italian population to be approximately 1:300,000 live births and defined a molecular testing algorithm designed to help diagnosing MPS IVA and foreseeing disease progression.

Genetic Diseases of PIEZO1 and PIEZO2 Dysfunction.

Abstract: Mutations in the genes encoding the mechanosensitive cation channels PIEZO1 and PIEZO2 are responsible for multiple hereditary human diseases. Loss-of-function mutations in the human PIEZO1 gene cause autosomal recessive congenital lymphatic dysplasia. Gain-of-function mutations in the human PIEZO1 gene cause the autosomal dominant hemolytic anemia, hereditary xerocytosis (also known as dehydrated stomatocytosis). Loss-of-function mutations in the human PIEZO2 gene cause an autosomal recessive syndrome of muscular atrophy with perinatal respiratory distress, arthrogryposis, and scoliosis. Gain-of-function mutations in the human PIEZO2 gene cause three clinical types of autosomal dominant distal arthrogryposis. This chapter will review the hereditary diseases caused by mutations in the PIEZO genes and will discuss additional physiological systems in which PIEZO channel dysfunction may contribute to human disease pathophysiology.

Mucopolysaccharidosis Type IVA

Abstract: Clinical characteristics The phenotypic spectrum of mucopolysaccharidosis IVA (MPS IVA) is a continuum that ranges from a severe and rapidly progressive early-onset form to a slowly progressive later-onset form. Children with MPS IVA typically have no distinctive clinical findings at birth. The severe form is usually apparent between ages one and three years, often first manifesting as kyphoscoliosis, genu valgum (knock-knee), and pectus carinatum; the slowly progressive form may not become evident until late childhood or adolescence, often first manifesting as hip problems (pain, stiffness, and Legg Perthes disease). Progressive bone and joint involvement leads to short stature, and eventually to disabling pain and arthritis. Involvement of other organ systems can lead to significant morbidity, including respiratory compromise, obstructive sleep apnea, valvular heart disease, hearing impairment, visual impairment from corneal clouding, dental abnormalities, and hepatomegaly. Compression of the spinal cord is a common complication that results in neurologic impairment. Children with MPS IVA have normal intellectual abilities at the outset of the disease. Diagnosis/testing The diagnosis of MPS IVA is established in a proband by identification of low N-acetylgalactosamine 6-sulfatase (GALNS) enzyme activity in cultured fibroblasts or leukocytes or by identification of biallelic pathogenic variants in GALNS on molecular genetic testing. Management Treatment of manifestations: Enzyme replacement therapy (elosulfase alfa) is available, although the data on long-term effects of this treatment on the skeletal and non-skeletal features of MPS IVA are limited. Evaluation and management of individuals with MPS IVA are best undertaken by multiple specialists, coordinated by a physician specializing in the care of persons with complex medical problems. Physiatrists, physical therapists, and occupational therapists help optimize mobility and autonomy. Psychological support can optimize coping skills and quality of life; educational professionals can optimize the learning environment for a medically fragile individual. Upper-extremity management may include stabilizing external wrist splints or partial or complete wrist fusion. Surgical intervention is often required for lower-extremity malalignment, hip subluxation and/or hip pain, upper cervical spine instability, and/or progressive thoracolumbar kyphosis. Cardiac valve involvement may require valve replacement. Bacterial endocarditis prophylaxis is recommended for those with a prosthetic cardiac valve, prosthetic material used for cardiac valve repair, or previous infective endocarditis. Upper-airway obstruction and obstructive sleep apnea are managed by removal of enlarged tonsils and adenoids; diffuse narrowing of the airway may require positive airway pressure and/or tracheostomy. All affected individuals should receive influenza and pneumococcal immunizations as well as routine immunizations. Anesthesia management by an experienced anesthesiologist. Potential pre- and postoperative anesthetic concerns secondary to spine anomalies and difficult airway management need to be anticipated. Optimize nutrition and provide adequate vitamin D and calcium. The outcome following keratoplasty for corneal opacification varies. Dental care to prevent cavities and orthodontic management as needed. Hearing loss is often treated initially with ventilation tubes and later with hearing aids. School accommodations as needed to prevent physical injury. Surveillance: For all individuals: physical examination at least every six months. Annual assessment of: pain severity; disease burden including quality of life and activities of daily living, endurance tests to evaluate functional status of the cardiovascular, pulmonary, musculoskeletal, and nervous systems; upper and lower extremities for functionality and malalignment, hips for dysplasia/subluxation, and thoracolumbar spine for kyphosis. Neurologic examination every six months to assess for spinal cord compression; yearly whole-spine MRI in neutral position and cervical spine flexion-extension MRI if the results are inconclusive; spine radiographs every two to three years. Annual assessment of heart rate; electrocardiogram and echocardiogram every one to three years depending on disease course. Polysomnography every three years to assess for obstructive sleep apnea; annual pulmonary function in children older than age five years until growth stops, then every two to three years. Monitor nutritional status using MPS IVA-specific growth charts. Perform vision and eye exam at least annually, dental evaluation every six to 12 months, and annual audiogram. For those on enzyme replacement therapy: annual assessment of pain, disease burden parameters, and pulmonary function tests; urine keratan sulfate or total glycosaminoglycans every six months. Agents/circumstances to avoid: Excessive weight gain; beta blockers. Genetic counseling MPS IVA is inherited in an autosomal recessive manner. If both parents are known to be heterozygous for a GALNS pathogenic variant, each sib of an affected individual has at conception 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. Once the GALNS pathogenic variants have been identified in an affected family member, carrier testing for at-risk family members, prenatal testing for a pregnancy at increased risk, and preimplantation genetic testing are possible.

Biochemical and molecular analysis in mucopolysaccharidoses: what a paediatrician must know

Abstract: Mucopolysaccharidoses (MPS) are rare inherited disorders caused by a deficit of the lysosomal hydrolases involved in the degradation of mucopolysaccharides, also known as glycosaminoglycans (GAGs). They are all monogenic defects, transmitted in an autosomal recessive way, except for MPS type II which is X-linked. The enzymatic deficit causes a pathologic accumulation of undegraded or partially degraded substrates inside lysosomes as well as in the extracellular compartment. MPS generally present with recognizable signs and symptoms to raise a clinical suspicion. However, although they have individual peculiarities, often signs and symptoms may overlap between different MPS types. Therefore, a deeper evaluation of specific disease biomarkers becomes necessary to reach an appropriate diagnosis. This paper stresses the central role of the laboratory in completing and confirming the clinical suspicion of MPS according to a standardized procedure: first, a biochemical evaluation of the patient samples, including qualitative/quantitative urinary GAG analysis and a determination of enzyme activities, and then the molecular diagnosis. We also encourage a constant and close communication between clinicians and laboratory personnel to address a correct and early MPS diagnosis.

Molecular diagnosis of patients affected by mucopolysaccharidosis: a multicenter study.

Abstract: Mucopolysaccharidoses (MPS) are a subgroup of 11 monogenic lysosomal storage disorders due to the deficit of activity of the lysosomal hydrolases deputed to the degradation of mucopolysaccharides. Although individually rare, all together they account for at least 1:25,000 live births. In this study, we present the genetic analysis of a population of 71 MPS patients enrolled in a multicenter Italian study. We re-annotated all variants, according to the latest recommendations, and re-classified them as suggested by the American College of Medical Genetics and Genomics. Variant distribution per type was mainly represented by missense mutations. Overall, 10 patients had received no molecular diagnosis, although 6 of them had undergone either HSCT or ERT, based on clinical and enzymatic evaluations. Moreover, nine novel variants are reported. Conclusions: Our analysis underlines the need to complete the molecular diagnosis in patients previously diagnosed only on a biochemical basis, suggests a periodical re-annotation of the variants and solicits their deposition in public databases freely available to clinicians and researchers. We strongly recommend a molecular diagnosis based on the analysis of the “trio” instead of the sole proband. These recommendations will help to obtain a complete and correct diagnosis of mucopolysaccharidosis, rendering also possible genetic counseling.