Deficiency of Glucocerebrosidase Activity beyond Gaucher Disease: PSAP and LIMP-2 Dysfunctions.

Glucocerebrosidase (GCase) is a lysosomal enzyme that catalyzes the breakdown of glucosylceramide in the presence of its activator saposin C (SapC). SapC arises from the proteolytical cleavage of prosaposin (encoded by PSAP gene), which gives rise to four saposins. GCase is targeted to the lysosomes by LIMP-2, encoded by SCARB2 gene. GCase deficiency causes Gaucher Disease (GD), which is mainly due to biallelic pathogenetic variants in the GCase-encoding gene, GBA1. However, impairment of GCase activity can be rarely caused by SapC or LIMP-2 deficiencies. We report a new case of LIMP-2 deficiency and a new case of SapC deficiency (missing all four saposins, PSAP deficiency), and measured common biomarkers of GD and GCase activity. Glucosylsphingosine and chitotriosidase activity in plasma were increased in GCase deficiencies caused by PSAP and GBA1 mutations, whereas SCARB2-linked deficiency showed only Glucosylsphingosine elevation. GCase activity was reduced in fibroblasts and leukocytes: the decrease was sharper in GBA1- and SCARB2-mutant fibroblasts than PSAP-mutant ones; LIMP-2-deficient leukocytes displayed higher residual GCase activity than GBA1-mutant ones. Finally, we demonstrated that GCase mainly undergoes proteasomal degradation in LIMP-2-deficient fibroblasts and lysosomal degradation in PSAP-deficient fibroblasts. Thus, we analyzed the differential biochemical profile of GCase deficiencies due to the ultra-rare PSAP and SCARB2 biallelic pathogenic variants in comparison with the profile observed in GBA1-linked GCase deficiency.

Exosomal MicroRNAs as Potential Biomarkers of Hepatic Injury and Kidney Disease in Glycogen Storage Disease Type Ia Patients.

Glycogen storage disease type Ia (GSDIa) is an inherited metabolic disorder caused by mutations in the enzyme glucose-6-phosphatase-α (G6Pase-α). Affected individuals develop renal and liver complications, including the development of hepatocellular adenoma/carcinoma and kidney failure. The purpose of this study was to identify potential biomarkers of the evolution of the disease in GSDIa patients. To this end, we analyzed the expression of exosomal microRNAs (Exo-miRs) in the plasma exosomes of 45 patients aged 6 to 63 years. Plasma from age-matched normal individuals were used as controls. We found that the altered expression of several Exo-miRs correlates with the pathologic state of the patients and might help to monitor the progression of the disease and the development of late GSDIa-associated complications.

Impact of COVID-19 related healthcare crisis on treatments for patients with lysosomal storage disorders, the first Italian experience.

The direct and indirect effects of Coronavirus Disease-19 (COVID-19) pandemic, on Italian patients with lysosomal storage disorders receiving therapy, were analyzed by a phone questionnaire. No proved COVID-19 emerged among 102 interviewed. No problems were reported by patients receiving oral treatments. Forty-nine% of patients receiving enzyme replacement therapy in hospitals experienced disruptions, versus 6% of those home-treated. The main reasons of missed infusions were fear of infection (62.9%) and re-organization of the infusion centers (37%).

Can Tangier disease cause male infertility? A case report and an overview on genetic causes of male infertility and hormonal axis involved.

Tangier disease is an autosomal recessive disorder caused by mutations in the ABCA1 gene and characterized by the accumulation of cholesteryl ester in various tissues and a near absence of high-density lipoprotein. The subject in this investigation was a 36-year-old Italian man with Tangier disease. He and his wife had come to the In Vitro Fertilization Unit, Pesaro Hospital (Azienda Ospedaliera Ospedali Riuniti Marche Nord) seeking help regarding fertility issues. The man was diagnosed with severe oligoasthenoteratozoospermia. Testosterone is the sex hormone necessary for spermatogenesis and cholesterol is its precursor; hence, we hypothesized that the characteristic cholesterol deficiency in Tangier disease patients could compromise their fertility. The aim of the study was to therefore to determine if there is an association between Tangier disease and male infertility. After excluding viral, infectious, genetic and anatomical causes of the subject's oligoasthenoteratozoospermia, we performed a hormonal analysis to verify our hypothesis. The patient was found to be negative for frequent bacteria and viruses. The subject showed a normal male karyotype and tested negative for Yq microdeletions and Cystic Fibrosis Transmembrane Conductance Regulator gene mutations. A complete urological examination was performed, and primary hypogonadism was also excluded. Conversely, hormonal analyses showed that the subject had a high level of follicle stimulating hormone and luteinizing hormone, low total testosterone and a significant decline in inhibin B. We believe that the abnormally low cholesterol levels typically found in subjects with Tangier disease may result in a reduced testosterone production which in turn could affect the hormonal axis responsible for spermatogenesis leading to a defective maturation of spermatozoa.

Outcome of adult patients with X-linked hypophosphatemia caused by PHEX gene mutations.

X-linked hypophosphatemia (XLH) is the most common monogenic disorder causing hypophosphatemia. This case-note review documents the clinical features and the complications of treatment in 59 adults (19 male, 40 female) with XLH. XLH is associated with a large number of private mutations; 37 different mutations in the PHEX gene were identified in this cohort, 14 of which have not been previously reported. Orthopaedic involvement requiring surgical intervention (osteotomy) was frequent. Joint replacement and decompressive laminectomy were observed in those older than 40 years. Dental disease (63%), nephrocalcinosis (42%), and hearing impairment (14%) were also common. The rarity of the disease and the large number of variants make it difficult to discern specific genotype-phenotype relationships. A new treatment, an anti-FGF23 antibody, that may affect the natural history of the disease is currently being investigated in clinical trials.

Microdeletion 15q26.2qter and Microduplication 18q23 in a Patient with Prader-Willi-Like Syndrome: Clinical Findings.

The small interstitial deletion in the long arm of chromosome 15 causing Prader-Willi/Angelman syndrome is well known, whereas cases that report terminal deletions in 15q in association with the Prader-Willi-like phenotype are very rare. By using GTG-banding analysis, metaphase FISH, MLPA analysis, and genome-wide array CGH, we detected an unbalanced translocation involving a microdeletion of the distal part of 15q and a microduplication of the distal part of 18q. The unbalanced translocation was found in a boy that was referred with clinical suspicion of Prader-Willi syndrome. In the 15q-deleted region, 23 genes have been identified, and 13 of them are included in the OMIM database. Among these, the deleted IGFR1, MEF2A, CHSY1, and TM2D3 genes could contribute to the patient's phenotype. Seven genes are included in the duplicated chromosome segment 18q, but only one (CTDP1) is present in the OMIM database. We suggest that the deleted chromosome segment 15q26.2qter may be responsible for the phenotype of our case and may also be a candidate locus of Prader-Willi-like syndrome.

Role of LIMP-2 in the intracellular trafficking of ß-glucosidase in different human cellular models.

Acid ß-glucosidase (GCase), the enzyme deficient in Gaucher disease (GD), is transported to lysosomes by the lysosomal integral membrane protein (LIMP)-2. In humans, LIMP-2 deficiency leads to action myoclonus-renal failure (AMRF) syndrome. GD and AMRF syndrome share some clinical features. However, they are different from clinical and biochemical points of view, suggesting that the role of LIMP-2 in the targeting of GCase would be different in different tissues. Besides, the role of LIMP-2 in the uptake and trafficking of the human recombinant (hr)GCase used in the treatment of GD is unknown. Thus, we compared GCase activity and intracellular localization in immortalized lymphocytes, fibroblasts, and a neuronal model derived from multipotent adult stem cells, from a patient with AMRF syndrome, patients with GD, and control subjects. In fibroblasts and neuronlike cells, GCase targeting to the lysosomes is completely dependent on LIMP-2, whereas in blood cells, GCase is partially targeted to lysosomes by a LIMP-2-independent mechanism. Although hrGCase cellular uptake is independent of LIMP-2, its trafficking to the lysosomes is mediated by this receptor. These data provide new insights into the mechanisms involved in the intracellular trafficking of GCase and in the pathogeneses of GD and AMRF syndrome.

Long term effects of enzyme replacement therapy in an Italian cohort of type 3 Gaucher patients.

BACKGROUND: The chronic neuropathic form of Gaucher disease (GD3) is characterised by hepatosplenomegaly, anaemia, thrombocytopenia, bone alterations and central neurological involvement. Enzyme replacement therapy (ERT) has been demonstrated to be effective in non neuropathic Gaucher disease, but long term results in patients with GD3 are still limited and contrasting. A possible role of genotype in determining the response to ERT has been hypothesised. PATIENTS AND METHODS: All patients affected by GD3, treated with ERT, and followed-up in 4 different Italian centres (Udine, Catanzaro, Sassari and Florence) were included. Data on clinical conditions, laboratory values, neurological and neuropsychological examinations, radiological and electrophysiological features were collected retrospectively from clinical records. RESULTS: Ten patients (6 females, 4 males) with four different genotypes (L444P/L444P, L444P/F231I, P159T/unknown, C.115+1G>A/N188S) were identified. They received ERT infusions from 3 to 21years. Haematological parameters and organomegaly improved/normalised in all patients. Three patients showed severe progressive skeletal deformities. 6/10 patients were neurologically asymptomatic when they started ERT for systemic symptoms. During the follow-up, 2/6 developed an important central nervous system disease; 2/6 developed mild central symptoms; and 2/6 did not show any neurological symptom after 5, and 20years of treatment respectively, despite the presence of epileptiform abnormalities at the electroencephalogram. Overall, neurological involvement worsened over time in 6/10 patients, 3 of whom developed progressive myoclonic encephalopathy and died. CONCLUSIONS: ERT improved the systemic manifestations in patients with GD3, but was not able to counteract the progression of neurological symptoms in the long term.

Myocardial fibrosis as the first sign of cardiac involvement in a male patient with Fabry disease: report of a clinical case and discussion on the utility of the magnetic resonance in Fabry pathology.

BACKGROUND: Cardiovascular magnetic resonance (CMR) with late gadolinium enhancement (LGE) imaging is increasingly used to assess myocardial involvement in patients with Fabry disease, an X linked lipid storage disorder. However, it is often proposed as an optional tool. A different cardiomyopathic disease progression between male and female patients was hypothesised in previous studies, as in female myocardial fibrosis was found without left ventricular (LV) hypertrophy, while myocardial fibrosis was always detected in association to LV hypertrophy in men. CASE PRESENTATION: A male Caucasian patient, 19 years old, diagnosed through a family-based molecular screening, presented with LGE of the LV inferolateral wall evidenced at the CMR, without LV hypertrophy, or other clinical signs of the disease. CONCLUSION: This is the first report of cardiac fibrosis as the first sign of organ involvement in a male patient with Fabry disease. This finding stresses the importance of performing CMR with LGE imaging for the initial staging and monitoring of Fabry patients of both genders.

Enzyme replacement therapy in juvenile glycogenosis type II: a longitudinal study.

UNLABELLED: Glycogenosis type II, a genetic muscle-wasting disorder, results in a spectrum of clinical phenotypes. Enzyme replacement therapy is effective in the infantile form of the disease, while little is known about its effectiveness in late-onset disease, especially in juvenile patients. The purpose of this retrospective cohort study was to assess the long-term effects of enzyme replacement therapy (ERT) in juvenile glycogenosis type II (GSDII). Eight Italian juvenile GSDII patients, receiving biweekly infusions of 20 mg/kg recombinant human α-glucosidase for at least 72 months, were enrolled (median age at therapy start was 11.8 years). Six-minute walk test (6MWT) and forced vital capacity (FVC), measured in upright position, were chosen as the principal outcome measures. Global motor disability (modified Walton scale (WS)), muscle enzymes levels [creatine phosphokinase (CK), lactate dehydrogenase (LDH), aspartate transaminase (AST), alanine transaminase (ALT)] and body mass index (BMI) were also analysed both at baseline (therapy start) and annually afterwards. At baseline, most patients (six out of eight) did not show muscle function impairment (WS ≤ 2). The performance at 6MWT showed a slight improvement during follow-up as well as FVC. Muscle enzymes levels showed a clear decrease after the 1st year of treatment while remained stable afterwards. An overall decrease in BMI was also observed during follow-up, although at the individual level, trends were variable. CONCLUSION: ERT is effective in stabilising both motor and lung functions in juvenile patients with GSDII, possibly slowing down the rate of disease progression. Randomised controlled trials are needed to understand whether early treatment allows juvenile patients to reach adulthood with a more beneficial residual muscular function than untreated patients.

Fertility and pregnancy in women affected by glycogen storage disease type I, results of a multicenter Italian study.

BACKGROUND: Life expectancy of patients with glycogen storage disease (GSD) type I has improved considerably, opening new problems correlated with adult age. In females polycystic ovaries (PCOs) has been described as frequently associated with the disease, however successful pregnancies have been reported. Whether or not GSD I is associated with impaired reproductive function is still unclear. PATIENTS AND METHODS: Data about female patients with GSD Ia and Ib, who were 16 years or older, were obtained from clinical records and interviews. RESULTS: A total of 32 women with GSD I (25 GSD Ia, 7 GSD Ib), median age 26 years (range 16-55), were included. 9/32 patients had delayed menarche, 17/32 had irregular cycles, 8/22 had documented polycystic ovaries. Five successful spontaneous pregnancies in four patients with GSD Ia and two in a woman with GSD Ib were reported. The latter had development and enlargement of hepatic adenomas during pregnancies. CONCLUSION: Despite the high prevalence of irregular menstruation cycles and polycystic ovaries, fertility seems not to be impaired in women with GSD I. During pregnancy monitoring for adenoma development is mandatory.

Relief of nocturnal neuropathic pain with the use of cannabis in a patient with Fabry disease.

Neuropathic pain is one of the most invalidating symptoms in patients with Fabry disease (FD), affecting their quality of life, it is linked to small fiber neuropathy and it may not respond to available disease specific treatments. We report the case of a 32 years old man with classic FD and severe neuropathic pain who, after the failure of several standard pharmaceutical approaches, was treated with medical cannabis with relief of nocturnal pain and sleep improvement.

Safety outcomes and patients' preferences for home-based intravenous enzyme replacement therapy (ERT) in pompe disease and mucopolysaccharidosis type I (MPS I) disorder: COVID-19 and beyond.

BACKGROUND: The Italian Medicines Agency (AIFA) demands precise information on benefit/risk profile of home-based enzyme replacement therapy (ERT) for the treatment of patients with Pompe disease and Mucopolysaccharidosis type I (MPS I). This passage is necessary to obtain the authorization for ERT home therapy, even after the coronavirus disease-19 (COVID-19) pandemic period. This research intends to evaluate the safety, treatment satisfaction, and compliance of MPS I patients treated with laronidase (Aldurazyme®) and Pompe Disease patients treated with alglucosidase alfa (Myozyme®) in a homecare setting. RESULTS: We report herein an early interim analysis of the HomERT (Home infusions of ERT) study, a multicenter, non-interventional, double-cohort study that retrospectively analyzed 38 patients from 14 sites in Italy: cohort A (Pompe disease - 32 patients) and cohort B (MPS I - 6 patients). Among the selected patients who started home therapy before enrollment, the average number of missed home-based infusions was 0.7 (1.3) in cohort A and 3.8 (6.4) in cohort B with no return to the hospital setting. Irrespective of the treatment location, 3 prior ADRs per cohort were reported. The majority of patients preferred home-based infusions (cohort A: 96.9%; cohort B: 100%): the main reason was attributed to treatment convenience (cohort A: 81.3%; cohort B: 83.3%). Despite the underlying conditions, most patients self-evaluated their health as "good" (cohort A: 50%; cohort B: 83.3%). CONCLUSIONS: Evidence of favorable safety profile, improved treatment compliance and personal satisfaction validates the use of ERT with laronidase and alglucosidase alfa as a strong candidate for home therapy.

Novel mutations of ABCA1 transporter in patients with Tangier disease and familial HDL deficiency.

The objective of the study was the characterization of ABCA1 gene mutations in 10 patients with extremely low HDL-cholesterol. Five patients (aged 6 months to 76 years) presented with splenomegaly and thrombocytopenia suggesting the diagnosis of Tangier disease (TD). Three of them were homozygous for novel mutations either in intron (c.4465-34A>G) or in exons (c.4376delT and c.5449C>T), predicted to encode truncated proteins. One patient was compound heterozygous for a nucleotide insertion (c.1758_1759insG), resulting in a truncated protein and for a nucleotide substitution c.4799A>G, resulting in a missense mutation (p.H1600R). The last TD patient, found to be heterozygous for a known mutation (p.D1009Y), had a complete defect in ABCA1-mediated cholesterol efflux in fibroblasts, suggesting the presence of a second undetected mutant allele. Among the other patients, four were asymptomatic, but one, with multiple risk factors, had severe peripheral artery disease. Three of these patients were heterozygous for known mutations (p.R130K+p.N1800H, p.R1068C, p.N1800H), while two were carriers of novel mutations (c.1195-27G>A and c.396_397insA), predicted to encode truncated proteins. The pathogenic effect of the two intronic mutations (c. 1195-27G>A and c.4465-34A>G) was demonstrated by the analysis of the transcripts of splicing reporter mutant minigenes expressed in COS-1 cells. Both mutations activated an intronic acceptor splice site which resulted in a partial intron retention in mature mRNA with the production of truncated proteins. This study confirms the allelic heterogeneity of TD and suggests that the diagnosis of TD must be considered in patients with an unexplained splenomegaly, associated with thrombocytopenia and hypocholesterolemia.

Training competencies in adult metabolic medicine: A survey of working adult metabolic medicine physicians.

The rapid expansion of the number of adult patients with inherited metabolic diseases (IMDs) has created demand for physicians with expertise in the field of adult metabolic medicine (AMM). Unfortunately, existing accredited training programs in this field are rare, and training programs in pediatric metabolic medicine cannot fully meet the needs of AMM physicians as the types of patients and the problems they face are different in the adult setting. We surveyed a group of working practitioners in AMM for input on what medical expert competencies they feel should be included as part of training programs in AMM. Through a modified Delphi process, 66 physicians from six continents reached consensus on a comprehensive list of training competencies in AMM. This list includes competencies from the fields of adult internal medicine, neurology, medical genetics, and pediatric metabolic medicine but also includes competencies not found in any of those programs, leading to the conclusion that the training needs for specialists in AMM cannot be met from any of these existing programs. We propose that AMM be considered a subspecialty separate from pediatric metabolic medicine and that accredited training programs in AMM be created using these medical expert competencies as part of a broader program design.

One year of COVID-19: infection rates and symptoms in patients with inherited metabolic diseases followed by MetabERN.

BACKGROUND: Since the beginning of the COVID-19 pandemic, MetabERN has been monitoring the SARS-CoV-2 infection rates within its metabolic community. To gather data on the total number of cases and the severity of symptoms among IMD patients one year into the pandemic, an online survey was distributed among all MetabERN healthcare providers (HCP). Epidemiological analysis was performed by integrating the survey's data with the MetabERN database. RESULTS: Survey's respondents reported a total of 452 cases of COVID-19 among their IMD patients (213 paediatric and 239 adults). Considering the total number of patients followed by the respondents (n = 26,347), the registered prevalence of COVID-19 in the IMD population was of 1716 × 100,000. Italy emerged as the most affected country (25.4% of cases), followed by the United Kingdom (14.2% of cases). Most of the paediatric cases of COVID-19 displayed no or mild symptoms during the disease: 34% of HCP reported having asymptomatic patients in 75-100% of cases, while 37.5% reported mild symptoms in about a quarter of their patients. Similarly to paediatric cases, most adult IMD patients with COVID-19 were asymptomatic or had mild symptoms: about one third of respondents reported 75-100% asymptomatic patients and about 65% of HCP had between 0 and 50% of patients with mild symptoms. The majority of the respondents reported no deaths due to COVID-19 in adult and paediatric patients with IMDs. CONCLUSIONS: Most of MetabERN's IMD patients who got COVID-19 during the first year of the pandemic had mild symptoms and a positive outcome of the disease. However, fatal events were recorded in paediatric patients; this, together with the lack of information on the long-term effects of COVID-19 in IMDs, call for caution in the metabolic population.

Urinary peptides as a diagnostic tool for renal failure detected by matrix-assisted laser desorption/ionisation mass spectrometry: an evaluation of their clinical significance.

The development of new analytical methodologies related to the proteome for the evaluation of renal physiology and pathology is surely of wide interest for physicians, giving them new tools for monitoring complications associated with diabetes, such as end-stage renal disease. In the present study, the clinical significance of the urinary abundance of two peptides, SGSVIDQSRVLNLGPITR (the uromodulin precursor, m/z 1912) and IGPHypGPHypGLMGPP [present in the collagen-α-5(IV) chain precursor, m/z 1219], detected by matrix- assisted laser desorption/ionisation mass spectrometry (MALDI/MS) in microalbuminuric or nephropathic diabetic patients and in non-diabetic nephropathic patients was evaluated. A progressive increase in the abundance of the ion at m/z 1219 and a decrease in the abundance of the ion at m/z 1912 have been found in diabetic microalbuminuric, diabetic-nephropathic and nephropathic patients. Linear correlations are present between serum creatinine values and the abundances of the ions at m/z 1219 (positive correlation, r=0.3645, P<0.0001) and at m/z 1912 (negative correlation, r=-0.3053, P<0.0005). Correlations between the MALDI data and the estimated glomerular filtration rate were also found, while relationships with urinary albumin excretion were found only in sub-sets of patients. Analysis of receiver operating characteristic curves showed a sensitivity up to 96% and a specificity of up to 84% for the two ionic species, or their ratio, for distinguishing diabetic patients with different degrees of nephropathy from healthy subjects, proving that the urinary abundance of the two peptides at m/z 1219 and m/z 1912, determined with MALDI/MS, may be considered as a possible diagnostic tool for the determination of progression toward renal failure, also with the aim of monitoring kidney function, in diabetic patients.

Focal hepatic lesions in acid sphingomyelinase deficiency: Differential diagnosis between foamy macrophages aggregates and malignancy.

Acid sphingomyelinase deficiency (ASMD) is a rare metabolic disorder due to biallelic mutation in the SMPD1 gene. The defect leads to the accumulation of sphingomyelin within the cells of the reticulo-endothelial system, particularly in the spleen, liver, lungs, and bone marrow causing hepato-splenomegaly, lung disease and hematological abnormalities. At present, data on abdominal imaging in ASMD are limited. Here we describe the characteristics of focal liver lesions observed in a 30 years old female. During the Magnetic Resonance follow up an increase in number and size of the lesions, showing T1 hypointensity and T2 hyperintensity with contrast enhancement, was observed. Contrast enhanced ultrasound evidenced rapid wash-in and steady isoecogenicity without appreciable wash-out at 80 seconds. The main lesion was biopsied to rule out the presence of a hepatocellular carcinoma, and showed to be a benign foamy macrophages aggregate. In this report, we discuss the possible pathogenesis of focal hepatic lesions in ASMD and their differential diagnosis.

Plasma Neurofilament Light (NfL) in Patients Affected by Niemann-Pick Type C Disease (NPCD).

(1) Background: Niemann-Pick type C disease (NPCD) is an autosomal recessive lysosomal storage disorder caused by mutations in the NPC1 or NPC2 genes. The clinical presentation is characterized by visceral and neurological involvement. Apart from a small group of patients presenting a severe perinatal form, all patients develop progressive and fatal neurological disease with an extremely variable age of onset. Different biomarkers have been identified; however, they poorly correlate with neurological disease. In this study we assessed the possible role of plasma NfL as a neurological disease-associated biomarker in NPCD. (2) Methods: Plasma NfL levels were measured in 75 healthy controls and 26 patients affected by NPCD (24 NPC1 and 2 NPC2; 39 samples). (3) Results: Plasma NfL levels in healthy controls correlated with age and were significantly lower in pediatric patients as compared to adult subjects (p = 0.0017). In both pediatric and adult NPCD patients, the plasma levels of NfL were significantly higher than in age-matched controls (p < 0.0001). Most importantly, plasma NfL levels in NPCD patients with neurological involvement were significantly higher than the levels found in patients free of neurological signs at the time of sampling, both in the pediatric and the adult group (p = 0.0076; p = 0.0032, respectively). Furthermore, in adults the NfL levels in non-neurological patients were comparable with those found in age-matched controls. No correlations between plasma NfL levels and NPCD patient age at sampling or plasma levels of cholestan 3ß-5α-6ß-triol were found. (4) Conclusions: These data suggest a promising role of plasma NfL as a possible neurological disease-associated biomarker in NPCD.