AISF update on the diagnosis and management of adult-onset lysosomal storage diseases with hepatic involvement

From Genes to Treatment: Literature Review and Perspectives on Acid Sphingomyelinase Deficiency in Children

Background: Acid sphingomyelinase deficiency (ASMD), most commonly known as Niemann-Pick disease (NPD), is a rare progressive genetic disorder regarding lipid storage. Subtypes A and B are inherited in an autosomal recessive fashion and consist of a genetic defect which affects the sphingomyelin phosphodiesterase 1 gene, leading to residual or lack of enzymatic activity of acid sphingomyelinase (ASM). Materials and Methods: This paper provides a brief history and overview to date of the disease and a comprehensive review of the current literature on ASMD in children, conducted on published papers from the past 10 years. Results: We identified 19 original publications (16 individual case reports and three series of cases-30 patients). The male/female ratio was 1.4. The youngest patient at disease onset was a female newborn with NPD-A. The youngest patient was diagnosed at 4 months. The longest timeframe between onset symptoms and diagnostic moment was 5 years 3 months. A total of nine patients exhibited red cherry macular spots. A total of 13 children exhibited associated lung disease, and four NPD-A patients with pulmonary disease died due to respiratory complications. A total of 11 children exhibited associated growth impairment. Genetic assays were performed in 25 cases (15 homozygous; 9 heterozygous). A total of four children (13.3%) received enzyme replacement therapy (ERT). Therapy outcomes included decreased liver and spleen volumes, improved platelet and leukocytes counts, and body mass index and stature improvement. Conclusions: Sometimes, a small child with a big belly hides a huge dilemma; inherited metabolic disorders are here to challenge clinicians and set the record straight, and genetics is the way of the future in terms of diagnosis and novel treatments. NPD must be considered children with persistent and progressive hepatosplenomegaly and growth failure. Diagnosis requires good clinical skills and access to genetic assays. Since 2022, the FDA has given a green light to a revolutionary enzymatic replacement therapy with human recombinant ASM called Olipudase-alfa. Clinical trial outcomes support its reliability and efficacy in the pediatric population.

[Adult and pediatric thesaurismosis: Lysosomal, lipid and glycogen storage diseases]

Thesaurismosis or storage diseases are rare genetic disorders due to an abnormal accumulation of an organic compound or its metabolite within cells. These conditions are either secondary to a defect in catabolism caused by enzymatic dysfunction or to a deficiency in transport proteins. They encompass lysosomal storage diseases, lipid storage diseases or dyslipidemias, and glycogen storage disorders or glycogenoses. Diagnosis is typically based on clinical and biological anomalies but may be made or suggested by the pathologist when symptoms are atypical or when biochemical or genetic tests are challenging to interpret. For accurate diagnosis, it is crucial to freeze a portion of the samples. Special staining and electronic microscopy can also aid in the diagnostic process. As the diagnosis is multidisciplinary, collaboration with clinicians, biochemists and geneticists is essential.

Lysosomal Acid Lipase Deficiency in the Etiological Investigation of Cryptogenic Liver Disease in Adults: A Multicenter Brazilian Study

Background: Lysosomal acid lipase deficiency (LAL-D) is a rare genetic disease associated with the deregulation of lipid metabolism, leading to atherosclerosis, dyslipidemia, and hepatic steatosis, with potential progression to cirrhosis. Our study aims to assess the role of LAL-D in the setting of cryptogenic liver disease. Methods: A large multicenter cross-sectional study was conducted, which included 135 patients with cryptogenic liver disease from four liver centers in Brazil. All patients were submitted to the investigation of LAL enzyme activity on dried blood spots. Results: Three patients (two female) presented levels of LAL below the reference limit, compatible with LAL-D (2.2%). They had a mean age of 43.9 ± 10.1 years and a mean body-mass index (BMI) of 23.1 ± 1.7 kg/m2. The mean serum levels of glucose, HDL-cholesterol, and triglycerides were 89.7 ± 3.2, 21.7 ± 3.2, and 206.7 ± 25.5 mg/dL, respectively. All patients had duodenal polyposis with xanthomatous macrophages. LAL-D investigation should be considered for individuals with chronic liver disease of an unknown etiology, especially with a normal BMI, high triglycerides, and low-HDL-cholesterol levels. The identification of LAL-D patients is extremely important since enzyme replacement therapy with Sebelipase Alfa significantly increases their survival.

Screening for lysosomal diseases in a selected pediatric population: the case of Gaucher disease and acid sphingomyelinase deficiency

BACKGROUND

GD and ASMD are lysosomal storage disorders that enter into differential diagnosis due to the possible overlap in their clinical manifestations. The availability of safe and effective enzymatic therapies has recently led many investigators to develop and validate new screening tools, such as algorithms, for the diagnosis of LSDs where the lack of disease awareness or failure to implement newborn screening results in a delayed diagnosis.

RESULTS

the proposed algorithm allows for the clinical and biochemical differentiation between GD and ASMD. It is based on enzyme activity assessed on dried blood spots by multiplexed tandem mass spectrometry (MS/MS) coupled to specific biomarkers as second-tier analysis.

CONCLUSIONS

we believe that this method will provide a simple, convenient and sensitive tool for the screening of a selected population that can be used by pediatricians and other specialists (such as pediatric hematologists and pediatric hepatologists) often engaged in diagnosing these disorders.

Similarities and differences between Gaucher disease and acid sphingomyelinase deficiency: An algorithm to support the diagnosis

Lysosomal storage disorders are a group of inborn errors of metabolism due to defects in proteins crucial for lysosomal function. Gaucher disease is the most common autosomal recessive lysosomal storage disorder due to mutations in the GBA1 gene, resulting in the lysosomal deficiency of glucocerebrosidase activity. Gaucher disease is characterized by the toxic accumulation of glucosylceramide in the reticuloendothelial system. Acid sphingomyelinase deficiency (ASMD), previously known as Niemann Pick A/B disease, is also an autosomal recessive lysosomal storage disorder due to mutations in the SMPD1 gene, which result in acid sphingomyelinase deficiency and the accumulation of sphingomyelin in mononuclear phagocytic system and hepatocytes. The phenotypic expression of Gaucher disease type 1 (GD1), the most common type, and chronic visceral ASMD may overlap for several signs or symptoms. Splenomegaly is detectable in approximately 90% of the patients in both conditions; however, since GD1 is more frequent than ASMD, clinicians are more prone to suspect it, often neglecting the diagnosis of ASMD. Based on previous experience, a group of experts in the clinical and laboratory diagnosis, management, and treatment of lysosomal storage disorders developed an algorithm for both GD1 and ASMD to support physicians, including primary care providers, internists, and specialists (e.g., hepatologists, hematologists, and pulmonologists) to suspect and differentiate GD1 and ASMD and to provide the appropriate referral.

Coenzyme Q10: Role in Less Common Age-Related Disorders

In this article we have reviewed the potential role of coenzyme Q10 (CoQ10) in the pathogenesis and treatment of a number of less common age-related disorders, for many of which effective therapies are not currently available. For most of these disorders, mitochondrial dysfunction, oxidative stress and inflammation have been implicated in the disease process, providing a rationale for the potential therapeutic use of CoQ10, because of its key roles in mitochondrial function, as an antioxidant, and as an anti-inflammatory agent. Disorders reviewed in the article include multi system atrophy, progressive supranuclear palsy, sporadic adult onset ataxia, and pulmonary fibrosis, together with late onset versions of Huntington’s disease, Alexander disease, lupus, anti-phospholipid syndrome, lysosomal storage disorders, fibromyalgia, Machado-Joseph disease, acyl-CoA dehydrogenase deficiency, and Leber’s optic neuropathy.

Natural history and management of liver dysfunction in lysosomal storage disorders

Lysosomal storage disorders (LSD) are a rare group of genetic disorders. The major LSDs that cause liver dysfunction are disorders of sphingolipid lipid storage [Gaucher disease (GD) and Niemann-Pick disease] and lysosomal acid lipase deficiency [cholesteryl ester storage disease and Wolman disease (WD)]. These diseases can cause significant liver problems ranging from asymptomatic hepatomegaly to cirrhosis and portal hypertension. Abnormal storage cells initiate hepatic fibrosis in sphingolipid disorders. Dyslipidemia causes micronodular cirrhosis in lipid storage disorders. These disorders must be keenly differentiated from other chronic liver diseases and non-alcoholic steatohepatitis that affect children and young adults. GD, Niemann-Pick type C, and WD also cause neonatal cholestasis and infantile liver failure. Genotype and liver phenotype correlation is variable in these conditions. Patients with LSD may survive up to 4-5 decades except for those with neonatal onset disease. The diagnosis of all LSD is based on enzymatic activity, tissue histology, and genetic testing. Enzyme replacement is possible in GD and Niemann-Pick types A and B though there are major limitations in the outcome. Those that progress invariably require liver transplantation with variable outcomes. The prognosis of Niemann-Pick type C and WD is universally poor. Enzyme replacement therapy has a promising role in cholesteryl ester storage disease. This review attempts to outline the natural history of these disorders from a hepatologist’s perspective to increase awareness and facilitate better management of these rare disorders.

Acid Sphingomyelinase Deficiency: A Clinical and Immunological Perspective

Acid sphingomyelinase deficiency (ASMD) is a lysosomal storage disease caused by deficient activity of acid sphingomyelinase (ASM) enzyme, leading to the accumulation of varying degrees of sphingomyelin. Lipid storage leads to foam cell infiltration in tissues, and clinical features including hepatosplenomegaly, pulmonary insufficiency and in some cases central nervous system involvement. ASM enzyme replacement therapy is currently in clinical trial being the first treatment addressing the underlying pathology of the disease. Therefore, presently, it is critical to better comprehend ASMD to improve its diagnose and monitoring. Lung disease, including recurrent pulmonary infections, are common in ASMD patients. Along with lung disease, several immune system alterations have been described both in patients and in ASMD animal models, thus highlighting the role of ASM enzyme in the immune system. In this review, we summarized the pivotal roles of ASM in several immune system cells namely on macrophages, Natural Killer (NK) cells, NKT cells, B cells and T cells. In addition, an overview of diagnose, monitoring and treatment of ASMD is provided highlighting the new enzyme replacement therapy available.

Liver steatosis is highly prevalent and is associated with metabolic risk factors and liver fibrosis in adult patients with type 1 Gaucher disease

BACKGROUND AND AIMS

Gaucher disease (GD) is associated with peculiar metabolic abnormalities (ie hypermetabolic state, peripheral insulin resistance, dyslipidaemia), partially reverted by enzyme replacement therapy (ERT) at the expense of weight gain. Such metabolic alterations together with an unhealthy lifestyle acquired by an ageing GD population may favour the development of liver steatosis. We aimed at evaluating the prevalence of significant liver steatosis and at identifying the factors associated with liver steatosis in a cohort of patients with type 1 GD.

METHODS

Twenty adult type 1 GD patients from an Italian academic referral centre were prospectively submitted to vibration-controlled transient elastography (Fibroscan®) with controlled attenuation parameter (CAP); significant steatosis was defined as CAP values ≥250 dB/min.

RESULTS

Median CAP values were 234 [165-358] dB/min and 8 patients (40%) had significant steatosis. Significant steatosis was associated with indices of adiposity (weight, BMI and waist circumference), high blood pressure, insulin resistance and metabolic syndrome. GD-related variables and dose and duration of ERT were not associated with significant steatosis. In the subgroup of 16 patients on stable ERT for at least 24 months, CAP resulted significantly and positively associated with liver stiffness (rho 0.559, P = .024).

CONCLUSIONS

Significant steatosis is highly prevalent in adult type 1 GD patients and is strongly associated with a worse metabolic profile, featuring metabolic dysfunction-associated fatty liver disease (MAFLD). MAFLD may determine liver fibrosis progression in GD patients on stable ERT and may be a risk factor for long-term liver-related complications.