Acid sphingomyelinase deficiency (ASMD) is a rare lysosomal disorder with diverse clinical presentations and often delayed diagnosis. This study investigates the clinical features, genetic variants, and treatment outcomes in Taiwanese patients. We retrospectively reviewed nine ASMD cases in Taiwan, including genetic data and responses to olipudase alfa. Newborn screening data using the NeoLSD MS/MS kit for dried blood spot enzyme activity, followed by lyso-sphingomyelin and molecular testing, were also analysed. The SMPD1 c.1497_1498inv variant was found in 62.5% of alleles among chronic neurovisceral ASMD cases, while c.995C > G appeared in 37.5% of chronic visceral ASMD cases and was also frequent in partial ASMD from newborn screening. Four patients received olipudase alfa; Patient 1, treated for 3 years starting at age 41, showed improved pulmonary function despite persistent thrombocytopenia and splenomegaly. Patients 2, 6, and 7, treated from early childhood, exhibited marked improvements in hepatosplenomegaly, interstitial lung disease, and growth within 1 year of therapy. This study highlights distinct genotype-phenotype correlations in ASMD and supports the clinical benefits of olipudase alfa. Increased awareness and early diagnosis, potentially through newborn screening, are essential for optimizing outcomes in ASMD.

Acid sphingomyelinase deficiency (ASMD), or Niemann-Pick disease types A, B, and A/B, is a rare lysosomal storage disorder caused by SMPD1 mutations. Clinical forms range from severe neurovisceral (type A) to chronic visceral (type B), mainly affecting the liver, spleen, and lungs. Until 2022, treatment was limited to supportive care. The approval of olipudase alfa for the non-central nervous system (CNS) manifestations of ASMD marked a major advance, with trials showing improvements in organ volumes and lung function. This meta-analysis evaluates the broader clinical impact of olipudase alfa in ASMD. A systematic search of Cochrane, PubMed, and Embase identified RCTs and cohort studies on olipudase alfa in patients with ASMD. Primary outcomes included mean change in %DLco, %Liver volume, and %Spleen volume; other secondary outcomes were also assessed. Study selection followed PRISMA guidelines, and statistical analyses were conducted using R software. The study was registered in PROSPERO CRD420251032281. Three studies (One RCT) encompassing 46 patients were included. Follow-up duration ranged from 1 to 6.5 years. All patients received olipudase alfa; only one study included a placebo group. Pooled results showed a mean DLco increase of 34.63% (95% CI: 26.09-43.18), a liver volume reduction of -37.76% (95% CI: -49.78 to -25.75), and a spleen volume reduction of -49.46% (95% CI: -57.39 to -41.53) after 2 years. The olipudase alfa demonstrates substantial clinical benefits in ASMD, significantly improving lung function and reducing organomegaly. Further studies are needed to confirm long-term safety and efficacy.

Acid sphingomyelinase deficiency is an ultra-rare disease characterised by generalised storage of sphingomyelin, caused by deficiency of the lysosomal enzyme acid sphingomyelinase, owing to the presence of biallelic pathogenic variants in the SMPD1 gene. The main disease manifestations are in the liver, spleen, lung and bone - with some patients having also involvement of the central nervous system. Patients show variable degrees of anaemia, thrombocytopenia and lipid abnormalities, among other findings. Clinically, acid sphingomyelinase deficiency spans from an acute neurovisceral form, with neurological involvement and early death (type A), to a chronic visceral disease, with no or minimal neurological manifestations (type B). An intermediate form, with chronic neurovisceral involvement, is presented by some patients (type A/B). Diagnosis involves the measurement of biomarkers, an assay of enzyme activity and genetic testing. Until a few years ago, treatment was mainly dependent on symptomatic management and bone marrow or solid organ (liver and/or lung) transplantation. In 2022, a specific enzyme replacement therapy with olipudase alfa was approved, and the results available indicate that it changed the therapeutic landscape for patients with acid sphingomyelinase deficiency type B and A/B. Research is being developed to address the needs of patients with acid sphingomyelinase deficiency type A, with gene therapy remaining as a promising approach.

Acid sphingomyelinase deficiency, formerly known as Niemann-Pick disease types B, A/B, and B, is a rare genetic disorder. It is an inherited autosomal recessive disease, linked to mutations in the SMPD1 gene. It is a lysosomal storage disease that leads to the accumulation of sphingomyelin mainly in macrophages, resulting in a multisystemic phenotype, primarily manifesting as hepatosplenomegaly and pulmonary involvement. The central nervous system may be affected, depending on the phenotype. Indeed, there is a phenotypic continuum among the three main forms that are distinguished: a chronic visceral form (formerly known as Niemann-Pick disease type B), a chronic neurovisceral form (intermediate form formerly known as Niemann-Pick disease type A/B), and an infantile neurovisceral form (formerly known as Niemann-Pick disease type A). The estimated overall prevalence is from 1 in 100,000 to 1 in 1,000,000 births. Clinical manifestations, as well as the age of onset of symptoms and/or diagnosis, vary depending on the form. The rarity of the disease and its nonspecific symptoms explain the diagnostic delay or failure to recognize the disease. Knowing and recognizing this disease is important, especially since there is an effective specific treatment through enzyme replacement therapy. In this article, we describe the clinical manifestations of acid sphingomyelinase deficiency, to understand when to suspect it, how to confirm it, and how to manage it.

Laboratory diagnosis of acid sphingomyelinase (ASM) deficiency (ASMD) was implemented in France in the early 1970s. The aims of this study were (i) to review the combined use of successively developed strategies - enzyme measurement, genetic testing, and biomarkers analysis - and (ii) to describe the mutational spectrum and epidemiological characteristics of a large patient cohort followed in French hospitals. During the 1974-2023 period, 271 patients with ASMD (238 families) were diagnosed. The chronic visceral form (historical Niemann-Pick type B) constituted 68 % of the cases, the infantile neurovisceral (type A) form 23 %, and the chronic neurovisceral (type AB) form 9 %. Profoundly deficient ASM activities were constantly observed in the neuronopathic forms. Elevated plasma concentrations of LysoSM and LysoSM-509/PPCS proved useful to comfort interpretation of ASM activities near cut-off found in leukocytes or dried blood spots of some patients with ASMD type B. Although not specific, LysoSM-509/PPCS appeared as the most sensitive biomarker. The spectrum of SMPD1 variants was investigated in 183 families. A total of 93 different SMPD1 variants (26 novel ones) was identified (58 % missense, 19 % frameshift, and 12 % nonsense ones). The proportion of null variants was much larger in ASMD type A (63 %) than in type B (24 %). In type AB, c.1177 T > G (p.Trp393Gly) contributed 32 % of the mutant alleles, most patients having Romani or Northwestern-Balkanic roots, while c.880C > A (p.Gln294Lys) only accounted for 9 %. Homoallelic variants in neuronopathic patients allowed genotype/phenotype correlations. In type B, c.1829_1831delGCC (p.Arg610del) represented 57 % of alleles, with a wide diversity of other variants. Among type B families, approximately one-third had a North African origin, and this variant accounted for 91 % alleles in this subgroup, compared to 40 % in non-North-African families. In patients homozygous for p.Arg610del (n = 69), the age at biological diagnosis was significantly higher (34.0 years; IQR 7.4-45.3) than in patients with either one (n = 41) [4.3 years; IQR 2.77-18.30] or no such allele (n = 43) [6.3 years; IQR 2.2-31.7]. A further observation was the proportional increase in the number of type B patients diagnosed after the age of 30 years since 2015. This nearly complete national cohort allowed a tentative evaluation of (minimal) incidences at birth as follows: ASMD (all clinical forms): 0.70/100,000; type B: 0.48/100,000; neuronopathic types (A and AB): 0.22/100,000. This comprehensive cohort (i) summarizes the real-life experience of laboratory diagnosis of ASMD in two expert centres, (ii) confirms the high frequency of the p.Arg610del allele in France and discloses some characteristics of patients homozygous for this variant; (iii) provides for the first time data on the distribution, mutational spectrum and tentative incidence at birth of the three clinical phenotypes of ASMD in France.