Long-range PCR amplification-based targeted enrichment & next generation sequencing: A cost-effective testing strategy for lysosomal storage disorders

Background & objectives: Lysosomal storage disorders (LSDs) are genetic metabolic disorders which result from deficiency of lysosomal enzymes or defects in other lysosomal components. Molecular genetic testing of LSDs is required for diagnostic confirmation when lysosomal enzyme assays are not available or not feasible to perform, and for the identification of the disease causing genetic variants. The aim of this study was to develop a cost-effective, readily customizable and scalable molecular genetic testing strategy for LSDs. Methods: A testing method was designed based on the in-house creation of selective amplicons through long range PCR amplification for targeted capture and enrichment of different LSD genes of interest, followed by next generation sequencing of pooled samples. Results: In the first phase of the study, standardization and validation of the study protocol were done using 28 samples of affected probands and/or carrier parents (group A) with previously identified variants in seven genes, and in the second phase of the study, 30 samples of enzymatically confirmed or biopsy-proven patients with LSDs and/or their carrier parents who had not undergone any prior mutation analysis (group B) were tested and the sequence variants identified in them through the study method were validated by targeted Sanger sequencing. Interpretation & conclusions: This testing approach was found to be reliable, easily customizable and cost-effective for the molecular genetic evaluation of LSDs. The same strategy may be applicable, especially in resource poor settings, for developing cost-effective multigene panel tests for other conditions with genetic heterogeneity.

Utility of morphologic assessment of bone marrow biopsy in diagnosis of lysosomal storage disorders

Introduction: Lysosomal storage disorders (LSDs) are rare disorders and pose a diagnostic challenge for clinicians owing to their generalized symptomatology. In this study, we aim to classify LSDs into two broad categories, namely, Gaucher disease (GD) and Niemann–Pick/Niemann–Pick-like diseases (NP/NP-like diseases) based on the morphology of the storage cells in the bone marrow (BM) aspiration smears and trephine biopsy sections. Materials and Method: This retrospective study includes 32 BM specimens morphologically diagnosed as LSDs at our institute, in the last 10 years. Subsequently, they were subclassified into GD and NP/NP-like diseases. Further, we have compared and analyzed the clinical, hematological, and biochemical parameters for the two groups of LSDs. Results: Based on BM morphology, 59.4% (n = 19) cases were diagnosed as NP/NP-like diseases and 40.6% (n = 13) cases as GD. Abdominal distension and failure to thrive were the most common clinical manifestations in both groups of LSDs. Anemia and thrombocytopenia were frequently seen in either of the LSDs. On the assessment of metabolic profile, elevated total/direct bilirubin and liver enzymes were more commonly seen in NP/NP-like diseases when compared with GD. Conclusion: We have classified LSDs into GD and NP/NP-like diseases based on the morphology of the storage cells in the BM specimen. The hallmark findings on BM biopsy annexed with the comparative features of the two proposed categories can aid the clinician in clinching the diagnosis. Formulation of such a methodology will prove instrumental for patient care in an underresourced setting.

Disease spectrum analysis of 1 520 cases with lysosomal storage disorders / 中华实用儿科临床杂志

Objective:To analyze the disease spectrum of lysosomal storage disorders(LSDs) and explore the prevalent distributions of different LSD types in one center in Shanghai.Methods:A retrospective analysis was made.A total of 5 476 suspected LSD patients, including 3 415 males and 2 061 females, with a median age of 4 years(1 day to 72 years), were collected from Xinhua Hospital, Shanghai Jiaotong University School of Medicine from August 2008 to May 2022.The activity of different lysosomal enzymes was detected by fluorescent and biochemical methods.Results:A total of 1 520 patients were diagnosed with LSDs, including 972 males and 548 females, with a median age of 4 years(1 day to 59 years), involving 19 different subtypes.Mucopolysaccharidosis(MPS) was the most common type among LSDs, with a frequency of 45.46%(691/1 520), followed by sphingolipidoses [33.88%(515/1 520)] and glycogen storage disease type Ⅱ [16.05%(244/1 520)] successively.MPS Ⅱ was the most common type in MPS, with a frequency of 45.73%(316/691), followed by MPS ⅣA [22.87%(158/691)]. Niemann-Pick A/B, Gaucher, and Krabbe diseases were common in Sphingolipidoses patients, with frequencies of 37.09%(191/515), 34.37%(177/515), and 10.29%(53/515), respectively.Conclusions:LSDs are common genetic metabolic diseases, especially MPS and sphingolipidoses.Newborn screening for LSDs should be carried out timely so that the patients can be treated early and their prognosis can be improved.

Review and Proposal of Alternative Technologies for Comprehensive and Reliable Newborn Screening Using Paper Borne Urine Samples for Lysosomal Storage Disorders: Glycosphingolipid Disorders

Abstract Few current methods are efficient to detect a high number of lysosomal storage disorders (LSDs) in newborn screening. Therefore, we propose a stepwise procedure that starts with the use of paper borne urine samples (Berry-Woolf specimen) for the inexpensive detection of elevated lysosomal content and the identification of which of the three majors biochemical groups -mucopolysaccharides, oligosaccharides, and glycosphingolipids- is detected. Urine samples are preferable to blood samples because of their higher concentrations of the relevant analytes. Subsequent steps would precisely determine which enzyme deficiency is involved. As a summary, following our previous papers on the detection of elevated oligosaccharides and mucopolysaccharides, here we describe how elevated urinary glycosphingolipids (GSLs) could be fluorometrically detected using the reagent 5-hydroxy-1-tetralone (HOT) and subsequently identified with precision by continuous thin layer chromatography or other techniques. We also outline the steps required for the validation of this procedure for its introduction in newborn screening programs.

A Case Report on the Challenging Diagnosis of Neuronal Ceroid Lipofuscinosis Type 2 (CLN2)

Abstract Neuronal ceroid lipofuscinoses (NCLs), also referred as "Batten disease", are a group of thirteen rare genetic conditions, which are part of the lysosomal storage disorders. CLN type 2 (CLN2) is caused by the deficient activity of the tripeptidyl peptidase I (TPP1) enzyme, encoded by the TPP1 gene, most frequently leading to the classic late infantile phenotype. Nearly 140 CLN2-causing mutations have been described. In this case report, we describe the identification of a new disease-causing mutation and highlight the importance of appropriate laboratory investigation based on clinical suspicion. The collection of dried blood spots (DBS) on filter paper, which is a convenient sample, can be used to measure the TPP1 enzyme activity and detect CLN2-related mutations. Since the biochemical and genetic diagnoses are possible and as the disease progression is fast and the therapeutic window is short, the investigation of CLN2 should be always considered when this diagnostic hypothesis is raised in order to enable the patients to benefit from the specific pharmacological treatment.

Aortic Valve Replacement for Two Siblings with Mucolipidosis Type III / 日本心臓血管外科学会雑誌

Mucolipidosis is an autosomal recessive lysosomal storage disorder that demonstrates a clinical resemblance to mucopolysaccharidosis. Accumulation of glycoproteins throughout the body causes dysfunction of several organs, in particular, valvular heart diseases are an important cause of mortality, however, there is no consensus guideline regarding the indications and optimal timing of the surgical repair because of the unclear and short natural history. Here we present 12- and 15-year-old siblings diagnosed with mucolipidosis who underwent aortic valve replacement. The senior sibling received redo-aortic valve replacement for prosthetic valve dysfunction 11 years after the initial surgery. A few surgical valve replacements in patients with mucopolysaccharidosis have been reported, however, there is no published case of aortic valve replacements in two siblings with mucolipidosis.

Gene Therapy for Lysosomal Storage Disorders: Recent Advances and Limitations

Abstract Lysosomal storage disorders (LSDs) are a group of diseases with multisystemic features. Current treatments have limitations and gene therapy arises as a promising treatment option. Here, we discuss some of the most recent studies for gene therapy in LSD, vectors used, and outcomes. In particular, the approaches used in animal models aiming to correct the central nervous system, the eye, and the bones are highlighted. Finally, we discuss the recent reports of clinical trials using this technology for these diseases. We conclude that gene therapy for LSD has gathered a substantial amount of evidence from animal models to know its potential and limitations. First evidences from clinical trials using both adeno-associated and lentiviral vectors show that this approach is safe and efficient and therefore could provide an effective treatment for several LSD in the near future.

Dermatologic Aspects of Fabry Disease

Abstract Isolated angiokeratomas (AKs) are common cutaneous lesions, generally deemed unworthy of further investigation. In contrast, diffuse AKs should alert the physician to a possible diagnosis of Fabry disease (FD). Angiokeratomas often do not appear until adolescence or young adulthood. The number of lesions and the extension over the body increase progressively with time, so that generalization and mucosal involvement are frequent. Although rare, FD remains an important diagnosis to consider in patients with AKs, with or without familial history. Dermatologists must have a high index of suspicion, especially when skin features are associated with other earlier symptoms such as acroparesthesia, hypohidrosis, or heat intolerance. Once the diagnosis is established, prompt screening of family members should be performed. In all cases, a multidisciplinary team is necessary for the long-term follow-up and treatment.

The Link Between Lysosomal Storage Disorders and More Common Diseases

Abstract In the last decades, it has become more and more evident that lysosomal storage disorders and common neurodegenerative diseases such as Alzheimer and Parkinson diseases have clinical, neuropathological, and genetic features in common, including lysosomal dysfunction and impaired autophagy. Patients with Gaucher and even carriers of Gaucher disease have an increased risk to develop Parkinson disease. Likewise, individuals who are heterozygous for a mutation of a gene that causes an adult form of neuronal ceroid lipofuscinosis are more likely to be affected by a form of frontotemporal dementia in their later life. A further example is the gene NAGLU encoding the enzyme α-N-acetylglucosaminidase, which is deficient in patients with mucopolysaccharidosis type IIIB. Mutations of the NAGLU gene have been observed in patients affected by an axonal neuropathy. An interesting unexpected finding was the link between stuttering and genes that are essential for the function of all lysosomal enzymes. This review will present some example of the association of lysosomal storage disorders and neurodegenerative disease and discuss possible pathogenic mechanisms that are common to both conditions. The understanding of the pathophysiology of the endosomal-lysosomal-autophagic system may help to develop drugs, which might provide benefit not only for patients with rare lysosomal storage disorders but also for individuals affected by more common diseases.

Lysosomes, Lysosomal Storage Diseases, and Inflammation

Abstract Lysosomes were originally described in the early 1950s by de Duve who was also the first to recognize the importance of these organelles in human disease. We know now that lysosomes are involved in numerous biological processes, and abnormalities in lysosomal function may result in a broad range of diseases. This review will briefly discuss the role of lysosomes in inflammation and how disruption of normal lysosomal function in the lysosomal storage diseases (LSDs) leads to abnormalities in inflammation and immunity.

Small Molecules: Substrate Inhibitors, Chaperones, Stop-Codon Read Through, and Beyond

Abstract Lysosomal storage disorders are rare genetic disorders due to deficient lysosomal activity, which leads to progressive accumulation of nonmetabolized substrates. Patient's clinical outcomes have significantly improved since the advent of enzyme replacement therapy, even though this therapeutic approach presents important limitations, such as immune reactions, low bioavailability of recombinant enzymes, and incapability to reach the central nervous system. New strategies based on gene therapy or small molecules have been proposed and tested as an alternative to enzyme replacement therapy or to complement it. Small molecules are orally administrated, no antigenic compound that can diffuse across cell membranes and distribute in steady-state concentrations, also reaching the central nervous system. Substrate reduction therapy, pharmacological chaperones, and stop-codon read-through enhancers are small molecules currently available for the treatment of lysosomal storage disorders. This article describes the characteristics of this class of compounds and the possible strategies to improve their efficiency in future development.

Spectrum of Lysosomal Storage Disorders at a Medical Genetics Center in Northern India.

Background: There is limited literature available on the phenotypic and mutation spectrum of Indian patients with Lysosomal storage disorders (LSD). Objective: To elucidate the clinical, biochemical and mutation spectrum and to study the management options in Indian patients with lysosomal storage disorders. Design: Descriptive study. Subjects and Methods: All patients with lysosomal storage disorders diagnosed in the Medical Genetics department of a tertiary care institute in North India over a three year period from January 2008 to December 2010. Results: Out of the total of 93 patients clinically suspected to have LSDs, 68 (mean age at presentation 4.5 years) were confirmed to have LSDs based on the laboratory/neuroimaging findings and documentation of deficient enzymatic activity in the peripheral blood (leucocytes or plasma) and/or skin fibroblasts. The commonest clinical features at presentation were growth retardation (failure to thrive 47.2% and short stature 17.6%), hepatosplenomegaly (41.2%) and neuroregression (33.8%). A history of consanguinity was present in 32.4% of the families. Prenatal diagnosis was done in a total of 6 affected families; two pregnancies were found to be affected (one each with Gaucher disease and Tay Sachs disease) and in both cases the parents opted for termination of pregnancy. Of the remaining four pregnancies which were found to be unaffected and therefore continued, three were confirmed to be normal on post-natal follow up. Enzyme replacement therapy (ERT) is being given for a total of 8 LSD patients and all of them are showing a gradual amelioration of their symptoms and an improvement in the quality of life. Conclusions: Lysosomal storage disorders constitute an important group of genetic metabolic disorders for many of which therapeutic options are now available.

Enfermedades por depósito lisosomal: diagnóstico a partir de lesiones cutáneas / Lysosomal storage diseases, diagnosis from skin lesions

Las enfermedades por depósito lisosomal (EDL) son un grupo heterogéneo de más de 40 dolencias genéticas, debidas a la deficiencia de diversas enzimas encargadas de metabolizar sustancias dentrode los lisosomas. Estas macromoléculas se depositan dentro de las organelas de múltiples órganos y dan lugar a diversos signos y síntomas.Muchas de estas enfermedades tienen manifestaciones cutáneas, e incluso en algunas oportunidades es el dermatólogo quien sospecha el diagnóstico a partir de las lesiones en piel.En el presente trabajo se describen 8 pacientes con EDL, diagnosticados en nuestro servicio entre 2009 y 2010, en los cuales las lesiones en piel fueron la clave para arribar al diagnóstico.Cinco pacientes presentaban enfermedad de Fabry (un varón y 4 mujeres), uno mucopolisacaridosis 2 (sexo masculino), uno beta-manosidosis (sexo masculino) y el último galactosialidosis (sexo femenino).Los angioqueratomas fueron la manifestación cutánea más frecuente, y la clave diagnóstica en los pacientes con Fabry, el paciente con manosidosis y la paciente con galactosialidosis, mientras que la lesión en piel que llevó a sospechar mucopolisacaridosis 2 fueron manchas mongólicas aberrantes, algunas lenticulares, que comprometían el tronco.En cuatro pacientes el diagnóstico se confirmó por estudios enzimáticos en gota de sangre en papel de filtro, leucocitos y/u orina. En cinco pacientes (uno de los cuales ya había sido diagnosticado deforma bioquímica) se realizó estudio molecular. En todos los pacientes se hicieron los estudios complementarios necesarios para evaluar extensión del compromiso extracutáneo y necesidad de tratamientoespecífico (en aquellos pacientes en los cuales su enfermedad de base dispone de terapia de reemplazo enzimático). En uno de los pacientes con Fabry se inició terapia específica.El interés de nuestro trabajo radica en mostrar distintas EDL en las cuales el rol del dermatólogo fue fundamental para arribar al diagnóstico, resaltando..

Lysosomal-storage disorders are a group of more than 40 heterogeneous hereditary diseases dueto the deficiency of various lysosomal enzymes, in charge of the metabolization of macromolecules,with accumulation of the undigested substances inside those organelles througout severalorgans, deriving in the multiple symptoms and signs of these diseases.A great number of these diseases may have cutaneous lesions, and in many cases the dermatologistmay be the one to suggest the diagnosis.We describe eight patients with lisosomal storage diseases diagnosed at our hospital during 2009and 2010, on whom the cutaneous lesions were the clue to the diagnosis. Five patients were diagnosed as Fabry´s disease (1 male and 4 females), one as mucopolisaccharidosis2 (male), one as mannosidosis (male) and the last one as galactosyalidosis (female). Angiokeratomaswhere the most frequent cutaneous manifestation, and the key to the diagnosis inFabry’s, beta mannosidosis and galactosyalidosis, while aberrant and lenticular mongolian spotson the trunk led us to the diagnosis of mucopolissacharidosis 2.On four patients the diagnosis was confirmed by biochemical work-up. On five patients (one ofthem had already been confirmed with biochemistry) a genetic study was also performed.On all the patients studies where performed to evaluate the extension of the systemic disease andthe need of a specific treatment (for those diseases where it is available). One of the patients withFabry´s disease started the treatment soon after the diagnosis.We would like to emphasize the fundamental role of the dermatologist in diagnosing these diseases,stressing not only the academic importance of these rare diseases but also the possibility ofstarting in many of them specific enzyme replacement treatment.

Use of Tandem Mass Spectrometry for Newborn Screening of 6 Lysosomal Storage Disorders in a Korean Population / 대한진단검사의학회지

BACKGROUND: We evaluated the performance of multiplex tandem mass spectrometry (MS/MS) in newborn screening for detection of 6 lysosomal storage disorders (LSDs), namely, Niemann-Pick A/B, Krabbe, Gaucher, Fabry, and Pompe diseases and Hurler syndrome. METHODS: We revised the conditions and procedures of multiplex enzyme assay for the MS/MS analysis and determined the precision of our enzyme assay and the effects of sample amounts and incubation time on the results. We also measured the degree of correlation between the enzyme activities in the dried blood spots (DBSs) and those in the leukocytes. DBSs of 211 normal newborns and 13 newborns with various LSDs were analyzed using our revised methods. RESULTS: The intra- and inter-assay precisions were 2.9-18.7% and 8.1-18.1%, respectively. The amount of product obtained was proportional to the DBS eluate volume, but a slight flattening was observed in the product vs. sample volume curve at higher sample volumes. For each enzyme assay, the amount of product obtained increased linearly with the incubation period (range, 0-24 hr). Passing and Bablok regression analysis revealed that the enzyme activities in the DBSs and those in the leukocytes were favorably correlated. The enzyme activities measured in the DBSs were consistently lower in patients with LSDs than in normal newborns. CONCLUSIONS: The performance of our revised techniques for MS/MS detection and enzyme assays was of the generally acceptable standard. To our knowledge, this is the first report on the use of MS/MS for newborn screening of LSDs in an Asian population.

Plasma chitotriosidase activity in children with lysosomal storage disorders.

Chitotriosidase (ChT) is an enzyme that is selectively activated in tissue macrophage. This property of ChT makes it a potential marker for many disease process and prognostication. Present study has been carried out to know the significance of ChT as a screening marker in lysosomal storage disorders (LSDs) where tissue macrophage activation is commonly observed due to accumulation of substrate in various organs of the body. Study comprises of 20 healthy children in the age range of 10 days to 5 yrs and 56 children in the age range of 2.5 months to 13 yrs with regression of milestones, skeletal dysplasia, neuroregression and hepatosplenomegaly were selected for plasma ChT who had confirmed LSDs as carried out by specific lysosomal enzyme study from the leukocytes or fibroblasts. Plasma ChT was 55.21 ± 20.81 nmol/ml /hr in twenty healthy age matched controls. Plamsa ChT level was 42.88 to 79.78 nmol/ml/hr in thirteen of 56 (23.21%) children with LSDs like Morquio- B, Pompe, Metachromatic leucodystrophy (MLD), Sandhoff and Niemann-Pick disease type C (NPD-C). While in 43 (76.78%) children it was in the range of 213.74 to 23,511.40 nmol/ml/hr. who had LSDs like Morquio-B, Sly syndrome, MLD, GM2 Gangliosidosis, NPD-A/B and Gaucher disease (GD). Marked elevated ChT (4,000 to 23,511 nmol/ml/hr) was observed in all cases of GD (n=7) and NDP-A/B. It can be concluded from the present study that moderately raised activity of ChT can be utilized as a positive predictive test for certain LSD’s. Those with marked elevated ChT have confirmed GD or NPD-A/B making it a strong screening marker for this group of diseases.

Sphingolipidoses of lysosomal storage disorders / 临床儿科杂志

Objective Sphingolipidoses are a group of rare genetic disorders caused by catabolism defect of sphingolipids by lysosomal hydrolases with diverse presentations,and represent an important health problem to almost all ethnic populations. To date,there is no epidemiologic study on the prevalence of sphinglipidoses,individually,or as a group,in China. We set up a series of enzymatic assays that could make definite diagnoses with the aim to collect data for an epidemiologic investigation of sphingolipidoses and also pave the way to prenatal diagnosis to decrease the rate of inborn error of metabolism. Methods Patients with suspected sphingolipidosis were recruited from pediatric endocrinology and inherited metabolism outpatient clinics of Xinhua Hospital. Leukocytes were isolated with dextran from peripheral bloods. Activities of leukocyte acid β-glucosidase,acid sphingomyelinase,arylsulphatase A,galacto-cerebrosidase,beta-galactosidase were measured using their specific artificial fluorescent substrates,while arylsulfatase A was determined by a colorimetric assay with dipotassium 2-hydroxy-5-nitrophenyl sulfate as the substrate. Results In one year,we identified 17 patients with 5 different kinds of sphingolipidoses,including 3 patients with Gaucher disease,9 patients with Niemann-Pick type A/B,2 patients with metachromatic leukodystrophy,2 patients with Krabbe disease,and 1 patient with GM1 gangliosidosis. We made brief descriptions of disease characters of each different kind disease and compared our results with findings of other ethnic groups. Conclusions Sphinglipidoses was markedly under-diagnosed in China and general pediatricians should be alerted to sphinglipidoses.