The Importance of Molecular Testing for the Diagnosis of Fabry Disease Manifested by Cornea Verticillata Only

Aims: To describe a Fabry disease, that it’s diagnosis was only possible through the molecular test Presentation of Case: L.A.P. female, 42 years old, lawyer, seen by the ophthalmology department for routine consultation only with refractive complaints. Fundus of the eye: Mild narrowing with increased vascular brightness and presence of pathological arteriovenous crossings. The rest of the exam was within normal limits. Therefore, a genetic test with the dosage of the α-Gal enzyme was requested, which evidenced the alteration in it, confirming the diagnosis of Fabry disease. Discussion: A Fabry Disease (FD) is an inborn error of glycosphingolipid (GL) metabolism, resulting from deficient activity of the enzyme alpha-galactosidase A (α -Gal). It has X-chromosome-linked inheritance, affecting mainly males, with an estimated prevalence of 1:40,000 males. The expression of the disease in heterozygous female patients can vary from an asymptomatic condition to a severe systemic disease, like that which occurs in men. Conclusions: The ophthalmological examination played an important role in the diagnosis, as this change is highly suggestive of the disease, in order to avoid erroneous and late diagnoses that can cause consequences for patients with this condition.

Improving the Pharmacological Properties of Ciclopirox for Its Use in Congenital Erythropoietic Porphyria

Congenital erythropoietic porphyria (CEP), also known as Günther’s disease, results from a deficient activity in the fourth enzyme, uroporphyrinogen III synthase (UROIIIS), of the heme pathway. Ciclopirox (CPX) is an off-label drug, topically prescribed as an antifungal. It has been recently shown that it also acts as a pharmacological chaperone in CEP, presenting a specific activity in deleterious mutations in UROIIIS. Despite CPX is active at subtoxic concentrations, acute gastrointestinal (GI) toxicity was found due to the precipitation in the stomach of the active compound and subsequent accumulation in the intestine. To increase its systemic availability, we carried out pharmacokinetic (PK) and pharmacodynamic (PD) studies using alternative formulations for CPX. Such strategy effectively suppressed GI toxicity in WT mice and in a mouse model of the CEP disease (UROIIISP248Q/P248Q). In terms of activity, phosphorylation of CPX yielded good results in CEP cellular models but showed limited activity when administered to the CEP mouse model. These results highlight the need of a proper formulation for pharmacological chaperones used in the treatment of rare diseases.

Fabry disease: a case report

Fabry disease is a rare X-linked recessive inborn error of metabolism due to deficient activity of the lysosomal enzyme, a-galactosidase A (a-Gal A). This results in the tissue accumulation of uncleaved glycosphingolipids within vascular endothelial lysosomes of various organs including skin, heart, kidneys and brain. We report a case of Fabry disease, in an 18-year-old boy, who presented with unilateral leg swelling and angiokeratoma corporis diffusum. Birdem Med J 2021; 11(2): 145-147

Niemann-Pick disease type A: a case report

BACKGROUND Niemann-Pick disease (NPD) types A result from the deficient activity of sphingomyelinase. NPD type A is characterized by early-onset, progressive neurodegenerative course; systemic disease manifestations, including massive hepatosplenomegaly, interstitial lung disease, and cherry-red macula; and death in early childhood. The objective: to enhance the recognition of health care providers about the potential undiagnosed NPD because nonspecific clinical manifestation CASE PRESENTATION A 18-months-old boy was admitted to Dr. Kariadi Hospital with enlarged abdomen since seventh month old with failure to thrive. He also showed progressive loss of neurologic function, microcephaly with open major fontanelle, recurrent pulmonary and systemic infection. Physical examination revealed facial dysmorphic, milestone regression, under-nutrition, crackles in both lungs, hepatosplenomegaly with petechial in extremities and floppy infants. Laboratory investigations showed anemia (9.4 g/dL) and thrombocytopenia (73.000/mm3). The lactate dehydrogenase (482 U/L) and alkaline phosphatase (159, 03 IU/L) were higher than normal. Abdominal ultrasound revealed hepatomegaly with normal parenchyma and splenomegaly without nodule. Skeletal survey revealed Erlenmeyer flask deformity. Foam cell are detected in bone marrow puncture. Retcam examination showed cherry red spot at the macula. Bera revealed auditory neuropathy. The enzyme activity showed normal ?–Glucosidase (5.55 uM/hr) and chitotriosidase (105,8 nmol/ml) but low sphingomyelinases activity (0.30 uM/hr) which confirmed the diagnosis of NPD. DISCUSSION Niemann-Pick disease (NPD) types A result from the deficient activity of sphingomyelinase. NPD type A is characterized by early-onset, progressive neurodegenerative course; systemic disease manifestations, including massive hepatosplenomegaly, interstitial lung disease, and cherry-red macula; and death in early childhood. Type A is very rare and a severe infantile form with neurologic degeneration resulting in death usually by 3 years of age. No treatment available for type A and It’s a rare disease in Indonesia. CONCLUSION These investigations were able to diagnose this child as a NPD-Type A. Patient was closely monitored and symptomatic treatment was provided.

Incorporating genotyping to identify patients with G6PD deficiency

Background: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common X-linked enzyme disorder associated with hemolytic anemia after exposure to certain medications or foods. Activity testing is the gold standard for detecting G6PD deficiency; however, this test is affected by various hematologic parameters. Clinical G6PD genotyping is included in pharmacogenetic arrays and clinical sequencing and may be reconciled with activity results. Methods: Patients (n=1,391) enrolled on an institutional pharmacogenetic testing protocol underwent clinical G6PD genotyping for 164 G6PD variants. For the 446 patients with G6PD activity results, algorithms were designed to assign G6PD status, accounting for known interferences with the activity assay and for G6PD genotype results. We developed clinical decision support alerts to inform prescribers when high-risk medications were prescribed, warning of gene-drug interactions and recommending therapy alteration. Results: Of 1,391 patients with genotype, 1,334 (95.9%) patients were predicted to have normal G6PD activity, 30 (2.1%) were predicted to have variable G6PD activity, and 27 (2%) were predicted to have deficient G6PD activity. Of the 417 patients with a normal genotype and an activity result, 415 (99.5%) had a concordant normal G6PD phenotype. Of the 21 patients with a deficient genotype and an activity result, 18 (85.7%) had a concordant deficient activity result. Genotyping reassigned phenotype in 5 patients with discordant genotype and activity results: 3 switched from normal to deficient, and 2 switched from deficient to normal. Conclusion: G6PD activity and genotyping are two independent testing methods which can be used in conjunction to assign a more informed G6PD phenotype.

Temporospatial Development of Neuropathologic Findings in a Canine Model of Mucopolysaccharidosis IIIB

Mucopolysaccharidosis (MPS) IIIB is a neuropathic lysosomal storage disease characterized by the deficient activity of a lysosomal enzyme obligate for the degradation of the glycosaminoglycan (GAG) heparan sulfate (HS). The pathogenesis of neurodegeneration in MPS IIIB is incompletely understood. Large animal models are attractive for pathogenesis and therapeutic studies due to their larger size, outbred genetics, longer lifespan, and naturally occurring MPS IIIB disease. However, the temporospatial development of neuropathologic changes has not been reported for canine MPS IIIB. Here we describe lesions in 8 brain regions, cervical spinal cord, and dorsal root ganglion (DRG) in a canine model of MPS IIIB that includes dogs aged from 2 to 26 months of age. Pathological changes in the brain included early microscopic vacuolation of glial cells initially observed at 2 months, and vacuolation of neurons initially observed at 10 months. Inclusions within affected cells variably stained positively with PAS and LFB stains. Quantitative immunohistochemistry demonstrated increased glial expression of GFAP and Iba1 in dogs with MPS IIIB compared to age-matched controls at all time points, suggesting neuroinflammation occurs early in disease. Loss of Purkinje cells was initially observed at 10 months and was pronounced in 18- and 26-month-old dogs with MPS IIIB. Our results support the dog as a replicative model of MPS IIIB neurologic lesions and detail the pathologic and neuroinflammatory changes in the spinal cord and DRG of MPS IIIB-affected dogs.

Identification of rare defective allelic variants in cases of thiopurine S-methyltransferase deficient activity

Aim: To assess rare TPMT variants in patients carrying a deficient phenotype not predicted by the four more frequent genotypes (*2, *3A, *3B and *3C). Materials & methods: Next-generation sequencing of TPMT in 39 patients with a discordant genotype. Results: None of the variants identified explained the discordances assuming that they are of uncertain significance according to the Clinical Pharmacogenetics Implementation Consortium classification. Two unknown variants were detected and predicted to result in a splicing defect. We show that TPMT*16 and TMPT*21 are defective alleles, and TPMT*8 and TPMT*24 are associated with a normal activity. Conclusion: Whole-exon sequencing for rare TPMT mutations has a low diagnostic yield. A reassessment of the functional impact of rare variants of uncertain significance is a critical issue.

Acute Intermittent Porphyria in a Man with Dual Enzyme Deficiencies

Porphyrias are a heterogeneous group of metabolic disorders that result from the altered activity of specific enzymes of the heme biosynthetic pathway and are characterized by accumulation of pathway intermediates. Porphyria cutanea tarda (PCT) is the most common porphyria and is due to deficient activity of uroporphyrinogen decarboxylase (UROD). Acute intermittent porphyria (AIP) is the most common of the acute hepatic porphyrias, caused by decreased activity of hydroxymethylbilane synthase (HMBS). An Argentinean man with a family history of PCT who carried the UROD variant c.10_11insA suffered severe abdominal pain. Biochemical testing was consistent with AIP, and molecular analysis of HMBS revealed a de novo variant: c.344 + 2_ + 5delTAAG. This is one of the few cases of porphyria identified with both UROD and HMBS mutations and the first confirmed case of porphyria with dual enzyme deficiencies in Argentina.

Assessing the role of glycosphingolipids in the phenotype severity of Fabry disease mouse model

Fabry disease is caused by deficient activity of α-galactosidase A, an enzyme that hydrolyzes the terminal α-galactosyl moieties from glycolipids and glycoproteins, and subsequent accumulation of glycosphingolipids, mainly globotriaosylceramide (Gb3), globotriaosylsphingosine (lyso-Gb3), and galabiosylceramide. However, there is no known link between these compounds and disease severity. In this study, we compared Gb3 isoforms (various fatty acids) and lyso-Gb3 analogs (various sphingosine modifications) in two strains of Fabry disease mouse models: a pure C57BL/6 (B6) background or a B6/129 mixed background, with the latter exhibiting more prominent cardiac and renal hypertrophy and thermosensation deficits. Total Gb3 and lyso-Gb3 levels in the heart, kidney, and dorsal root ganglion (DRG) were similar in the two strains. However, levels of the C20-fatty acid isoform of Gb3 and particular lyso-Gb3 analogs (+18, +34) were significantly higher in Fabry-B6/129 heart tissue when compared with Fabry-B6. By contrast, there was no difference in Gb3 and lyso-Gb3 isoforms/analogs in the kidneys and DRG between the two strains. Furthermore, using immunohistochemistry, we found that Gb3 massively accumulated in DRG mechanoreceptors, a sensory neuron subpopulation with preserved function in Fabry disease. However, Gb3 accumulation was not observed in nonpeptidergic nociceptors, the disease-relevant subpopulation that has remarkably increased isolectin-B4 (the marker of nonpeptidergic nociceptors) binding and enlarged cell size. These findings suggest that specific species of Gb3 or lyso-Gb3 may play major roles in the pathogenesis of Fabry disease, and that Gb3 and lyso-Gb3 are not responsible for the pathology in all tissues or cell types.

A Rare Disease of Familial Chylomicronemia Syndrome in a 20 Days Infant

Familial chylomicronemia syndrome is a group of very rare genetic disorders. It is inherited as autosomal recessive disorder. Its estimated incidence is 1 in 1000000 populations, characterized by deficient activity of an enzyme lipoprotein lipase (LPL) or apo-protein C-II, resulting into severe fasting hypertriglyceridemia and massive accumulations of chylomicrons in plasma. LPL deficiency typically presents in childhood with failure to thrive, colicky abdominal pain, eruptive xanthomas, lipemiaretinalis, pancreatitis and hepatomegaly. We are reporting a rare case of familial chylomicronemia in a 20 days old child who was presented with pneumonia, his plasma incidentally found like milk during routine collection of his blood sample. As the child was only 20 days old with very high triglyceride level, so breast feeding continued and cocktail therapy with low dose Tablet Fenofibrate, Tablet Niacin, Tablet Atovastatin started after referral to paediatric cardiologist at 3 months of age. Journal of Armed Forces Medical College Bangladesh Vol.15 (1) 2019: 107-109