Unraveling the unexpected: Interference in iron assay leads to diagnosis of multiple myeloma.

BACKGROUND: Iron studies are critical for diagnosing iron deficiency and hemochromatosis. We present a case exhibiting macrocytic anemia with perplexingly high plasma iron concentrations. METHODS AND RESULTS: The initial clinical presentation with significantly elevated iron results raised concerns for hemochromatosis. However, inconsistent results in dilution studies suggested the presence of an interfering substance. Inspection of the reaction curves from the instrument revealed very high background absorption in the 800 nm channel. This, coupled with the observation of an insoluble precipitate upon mixing the acid buffer reagent with the patient's serum, as well as the patient's high total protein and low albumin levels, suggested immunoglobulin overproduction. Serum protein electrophoresis confirmed a monoclonal gammopathy with a subsequent diagnosis of multiple myeloma. CONCLUSION: Excessive monoclonal immunoglobulins can precipitate in acidic buffers and interfere with spectrophotometric measurements in iron testing. Although challenging, investigating an interference and determining its cause can uncover underlying diseases that have yet to be diagnosed.

Performance of OC-Auto Micro 80 Fecal Immunochemical Test in an Integrated Academic-Community Health System.

GOALS: We aimed to determine the performance of the OC-Auto Micro 80 fecal immunochemical test (FIT) in an average-risk population receiving care in an integrated, academic-community health system. BACKGROUND: The FIT is the most used colorectal cancer (CRC) screening test worldwide. However, many Food and Drug Administration-cleared FIT products have not been evaluated in clinical settings. STUDY: We performed a retrospective cohort study of patients (50 to 75 y old) in the University of Washington Medicine health care system who were screened for CRC by OC-Auto Micro 80 FIT between March 2016 and September 2021. We used electronic health records to extract patient-level and clinic-level factors, FIT use, colonoscopy, and pathology findings. The primary outcomes were the FIT positivity rate and neoplasms detected at colonoscopy. Secondary outcomes were FIT positivity by sex and safety-net versus non-safety-net clinical settings. RESULTS: We identified 39,984 FITs completed by 26,384 patients; 2411 (6.0%) had a positive FIT result (>100 ng/mL of hemoglobin in buffer), and 1246 (51.7%) completed a follow-up colonoscopy. The FIT positive rate was 7.0% in men and 5.2% in women (P <0.01). Among those who completed a colonoscopy after an abnormal FIT result, the positive predictive value for CRC, advanced adenoma, and advanced neoplasia was 3.0%, 20.9%, and 23.9%, respectively. CONCLUSIONS: In a retrospective analysis of a large heterogeneous population, the OC-Auto Micro 80 FIT for CRC screening demonstrated a positivity rate of 6.0% and a positive predictive value for CRC of 3.0%.

Very rare condition of multiple Gaucheroma: A case report and review of the literature.

BACKGROUND: This study presented a 3 years old boy with Gaucher disease (GD) who was treated with enzyme replacement therapy(ERT) for 19 months and developed multiple Gaucheroma. The literature was reviewed. METHODS: The medical chart and literature were reviewed. A boy presented at the age of 15 months with anemia, thrombocytopenia, and hepatosplenomegaly. Enzyme assay and gene mutations confirmed GD. ERT was administered. When the boy was 3 years old, multiple masses were discovered from abdominal MRI and biopsy revealed Gaucheroma. We reviewed 20 GD patients with Gaucheroma and Gaucher cell infiltrated lymphadenopathies. CONCLUSION: Gaucheroma is a rare condition in regularly treated GD patients. This patient showed poor response to doubled ERT doses. The imaging studies are necessary for Gaucher patients to detect Gaucheroma and determine their malignancy. Regular checkups are recommended in all GD patients even with ERT treatment, due to the possibility of having a deteriorating change, like Gaucheroma.

Very rare condition of multiple Gaucheroma: A case report and review of the literature.

BACKGROUND: This study presented a 3 years old boy with Gaucher disease (GD) who was treated with enzyme replacement therapy (ERT) for 19 months and then developed multiple Gaucheroma. Review of literature was performed simultaneously. METHODS: The medical chart and literature were reviewed. A boy presented at the age of 15 months with anemia, thrombocytopenia, and hepatosplenomegaly. GD was confirmed by enzyme assay and gene mutations. ERT was administered right after the diagnosis. When the boy was 3 years old, multiple masses were discovered during a regular checkup abdominal MRI and biopsy revealed Gaucheroma. We also reviewed 20 GD patients with Gaucheroma and Gaucher cell infiltrated lymphadenopathies. CONCLUSION: Gaucheroma is a rare condition of regularly treated GD patients. This patient even showed poor response to doubled ERT doses. The imaging studies are necessary for Gaucher patients to detect Gaucheroma and determine their malignancy. Regular checkups are recommended in all GD patients even with regular treatment, due to the possibility of having deteriorating change, like Gaucheroma.

Functional and biological studies of α-galactosidase A variants with uncertain significance from newborn screening in Taiwan.

Fabry disease is an X-linked disorder resulted from deficiency of α-galactosidase A (GLA) activity. In Taiwan, a total of 792,247 newborns were screened from 2008 to 2014 in two newborn screening centers, and 13 variants of uncertain significance (VOUS) in the GLA gene were identified. To determine whether these variants were pathogenic or not, functional, biochemical, clinical and pedigree analyses were performed. In vitro functional assay was established through site-directed mutagenesis, and four in silico tools were used to predict pathogenesis. The enzyme activity of dried blood spots and plasma metabolite lyso-Gb3 level from subjects with the variants were measured. Additionally, clinical manifestations were evaluated extensively from the subjects and their relatives. Our results revealed that p.G104V, p.I232T, p.D322H, and p.G360C all exhibited relatively low residual enzyme activities and elevated plasma lyso-Gb3 level. These data strongly suggest that these Fabry mutations may cause classical or later-onset phenotypes. In contrast, neither significantly clinical symptoms nor elevated lyso-Gb3 level was found in cases with p.P60S, p.A108T, p.S304T, p.R356Q, and p.P362T variants, which may be non-pathogenic or milder forms of Fabry variants. More data need to be included for the patients with p.N53D, p.P210S, p.M296L, and p.K391T variants. The established system provides us more information to classify these GLA variants.

Later Onset Fabry Disease, Cardiac Damage Progress in Silence: Experience With a Highly Prevalent Mutation.

BACKGROUND: Recently, several studies revealed a much higher prevalence of later onset Fabry disease (FD) than previously expected. It suggested that later onset FD might present as an important hidden health issue in certain ethnic or demographic populations in the world. However, the natural history of its phenotype has not been systemically investigated, especially the cardiac involvement. OBJECTIVES: The study analyzed a large-scale newborn screening program for FD to understand the natural course of later onset FD. METHODS: To date, 916,383 newborns have been screened for FD in Taiwan, including more than 1,200 individuals with the common, later onset IVS4+919G>A (IVS4) mutation. Echocardiography was performed in 620 adults with the IVS4 mutation to analyze the prevalence of left ventricular hypertrophy (LVH), and gadolinium-enhanced cardiac magnetic resonance imaging was performed in 129 patients with FD, including 100 IVS4 adults. RESULTS: LVH was observed in 67% of men and 32% of women older than 40 years. Imaging evidenced significant late gadolinium enhancement in 38.1% of IVS4 men and 16.7% of IVS4 women with the IVS4 mutation but without LVH. Seventeen patients underwent endomyocardial biopsies, which revealed significant globotriaosylceramide substrate accumulation in their cardiomyocytes. CONCLUSIONS: Significant cardiomyocyte substrate accumulation in IVS4 patients led to severe and irreversible cardiac fibrosis before development of LVH or other significant cardiac manifestations. Thus, it might be too late to start enzyme replacement therapy after the occurrence of LVH or other significant cardiac manifestations in patients with later onset FD. This study also indicated the importance of newborn screening for early detection of the insidious, ongoing, irreversible cardiac damage in patients with later onset FD.

Globotriaosylsphingosine (lyso-Gb3) might not be a reliable marker for monitoring the long-term therapeutic outcomes of enzyme replacement therapy for late-onset Fabry patients with the Chinese hotspot mutation (IVS4+919G>A).

BACKGROUND: In Taiwan, DNA-based newborn screening showed a surprisingly high incidence (1/875 in males and 1/399 in females) of a cardiac Fabry mutation (IVS4 + 919G > A). However, the natural course, long-term treatment outcomes and suitable biomarkers for monitoring the therapeutic outcomes of these patients are largely unknown. METHODS: Fabry disease (FD) patients who had received enzyme replacement therapy (ERT) for more than 1 year were enrolled in this study from December 2008 to April 2013. Periodic echocardiography and serum globotriaosylsphingosine (lyso-Gb3) analysis were carried out. Before and after ERT, left ventricular mass index (LVMI) and serum lyso-Gb3 level were compared and the correlation between the change of LVMI and the change of serum lyso-Gb3 were also analyzed. RESULTS: Thirty-six patients, in four patient groups, were enrolled: (1) 16 males with IVS4 + 919G > A mutation; (2) 7 females with IVS4 + 919G > A mutation; (3) 2 males with classical mutations; and (4) 11 females with classical mutations. The follow-up period was 13-46 months. There were significant LVMI reductions after ERT in all four groups after excluding confounding factors. However, interestingly, serum lyso-Gb3 decreased significantly in the early period after ERT in all groups, but increased gradually after an average of 11.1 months after ERT in late-onset male and female Fabry groups, even when their LVMI still decreased or remained stable. Furthermore, there was no correlation between the change of serum lyso-Gb3 and the change of LVMI in both classical and IVS4 + 919G > A FD patients. CONCLUSION: Although lyso-Gb3 has a high diagnostic sensitivity in late-onset Fabry patients and has a good response to ERT during the early stages, it might not be a reliable marker for monitoring the long-term therapeutic outcomes of ERT for late-onset Fabry patients with the Chinese hotspot mutation (IVS4 + 919G > A).

Endomyocardial biopsies in patients with left ventricular hypertrophy and a common Chinese later-onset Fabry mutation (IVS4 + 919G > A).

BACKGROUND: In Taiwan, DNA-based newborn screening showed a surprisingly high incidence of a cardiac Fabry mutation (IVS4 + 919G > A). The prevalence of this mutation is too high to be believed that it is a real pathogenic mutation. The purpose of this study is to identify the cardiac pathologic characteristics in patients with left ventricular hypertrophy and this mutation METHODS AND RESULTS: Endomyocardial biopsies were obtained in 22 patients (Median age: 61, males: 17; females: 5) with left ventricular hypertrophy and the IVS4 + 919G > A mutation; five patients had not received enzyme replacement therapy (ERT) before biopsy, while the other 17 patients had received ERT from 8 months to 51 months. Except for three patients who had received ERT for more than 3 years, all other patients showed significant pathological change and globotriaosylceramide (Gb3) accumulation in their cardiomyocytes. In contrast to classical Fabry patients, no Gb3 accumulation was found in the capillary endothelial cells of any of our patients. Fourteen patients (63.6%) were found to have myofibrillolysis. CONCLUSIONS: All of the untreated and most of the treated IVS4 + 919G > A patients showed typical pathological changes of Fabry disease in their cardiomyocytes. No endothelial accumulation of Gb3 was found, which is similar to the findings of several previous reports regarding later-onset Fabry disease. This result highly suggests that the IVS4 + 919G > A is a real pathogenic later-onset Fabry mutation.

Detecting multiple lysosomal storage diseases by tandem mass spectrometry--a national newborn screening program in Taiwan.

BACKGROUND: Interest in lysosomal storage diseases in newborn screening programs has increased in recent years. Two techniques, fluorescence (4-MU) and tandem mass spectrometry (MS/MS) methods are frequently used. We report a pilot study of large scale newborn screening for Fabry, Pompe, Gaucher, and MPS I diseases by using the MS/MS method in Taiwan and compared the performance of the MS/MS with 4-MU methods. METHODS: More than 100,000 dried blood spots (DBSs) were collected consecutively as part of the national Taiwan newborn screening programs. The enzyme activities were detected by the MS/MS method from a DBS punch. Mutation analysis was further performed for newborns with detected enzyme deficiency. RESULTS: The DNA sequence analysis for suspected cases revealed 64 newborns with confirmed Fabry mutations, 16 were classified as infantile or late-onset Pompe disease, and 1 was characterized as Gaucher disease. The positive predict value increased from 4.0% to 7.1% in the Pompe study, and from 61.0% to 95.5% in the Fabry study by the MS/MS method compared to 4-MU assay. CONCLUSIONS: The MS/MS method has been validated as a more specific, powerful and efficient tool than the 4-MU assay. It also provided a multiplex solution of newborn screening for lysosomal storage diseases.

Clinical observations on enzyme replacement therapy in patients with Fabry disease and the switch from agalsidase beta to agalsidase alfa.

BACKGROUND: Fabry disease is an X-linked inherited lysosomal storage disease that can be treated with the enzymes of agalsidase beta (Fabrazyme) and agalsidase alfa (Replagal). Since June 2009, viral contamination of Genzyme's production facility has resulted in a worldwide shortage of agalsidase beta, leading to the switch to agalsidase alfa for patients with Fabry disease in Taiwan. METHODS: The medical records were retrospectively reviewed for nine male patients with Fabry disease from the start of agalsidase beta treatment until the switch to agalsidase alfa for at least 1 year. RESULTS: After 12-112 months of enzyme replacement therapy (ERT), decreased plasma globotriaosylsphingosine (lyso-Gb3) was found in five out of seven patients, indicating improvement in disease severity. Among the six patients with available echocardiographic data at baseline and after ERT, all six experienced reductions of left ventricular mass index. Renal function, including microalbuminuria and estimated glomerular filtration rate, showed stability after ERT. Mainz Severity Score Index scores revealed that all nine patients remained stable at 12 months after switching to agalsidase alfa. ERT improved or stabilized cardiac status and stabilized renal function, while reducing plasma lyso-Gb3. ERT was well tolerated, even among the three patients who had hypersensitivity reactions. CONCLUSION: The switch of ERT from agalsidase beta to agalsidase alfa appears to be safe after 1 year of follow-up for Taiwanese patients with Fabry disease.

Plasma globotriaosylsphingosine (lysoGb3) could be a biomarker for Fabry disease with a Chinese hotspot late-onset mutation (IVS4+919G>A).

BACKGROUND: Previous studies revealed a high incidence of late-onset Fabry disease mutation, IVS4+919G>A, in Taiwan. However, the natural course is largely unclear and suitable biomarkers for monitoring disease progress are unavailable. METHODS AND RESULTS: Patients carrying IVS4+919G>A or classical Fabry mutations were enrolled in this study. The subjects ranged from newborn to eighty year old adults. Plasma globotriaosylceramide (Gb3) and globotriaosylsphingosine (lysoGb3) were measured by LC-MS/MS in subjects to evaluate the sensitivity of these two biomarkers. All adult males and symptomatic females could be distinguished from healthy controls by an elevated plasma lysoGb3 level. The lysoGb3 level was also related to the left ventricular mass considering gender and age (p<0.01). Moreover, approximately 70% of male and 45% of female newborns already had an elevated plasma lysoGb3 level which increased gradually as the subjects got older (p<0.01). CONCLUSIONS: Plasma lysoGb3 is a more sensitive and reliable biomarker than plasma Gb3. LysoGb3 also correlated with age and left ventricular mass index in Fabry patients with IVS4+919G>A mutation. Because lots of infants with the IVS4+919G>A mutation already had elevated lysoGb3 levels at birth, that indicates that the development of hypertrophic cardiomyopathy may require a long and insidious course after lysoGb3 accumulation.