Fabry disease with early-onset ventricular dilation: A case report

Long-read sequencing enables comprehensive molecular genetic diagnosis of Fabry disease

BACKGROUND

The clinical diagnosis of Fabry Disease (FD) can be challenging due to the clinical heterogeneity, especially in females. Patients with FD often experience a prolonged interval between the onset of symptoms and receiving a diagnosis. Genetic testing is the gold standard for precise diagnosis of FD, however conventional genetic testing could miss deep intronic variants and large deletions or duplications. Although next-generation sequencing, which analyzes numerous genes, has been successfully used for FD diagnosis and can detect complex variants, an effective and rapid tool for identifying a wide range of variants is imminent, contributing to decrease the diagnostic delay.

METHODS

The comprehensive Analysis of FD (CAFD) assay was developed for FD genetic diagnosis, employing long-range PCR coupled with long-read sequencing to target the full-length GLA gene and its flanking regions. Its clinical performance was assessed through a comparative analysis with Sanger sequencing.

RESULTS

Genetic testing was performed on 82 individuals, including 48 probands and 34 relatives. The CAFD assay additionally identified variants in two probands: one had a novel and de novo pathogenic variant with a 1715 bp insertion in intron 4, and the other carried two deep intronic VUS variants in cis-configuration also in intron 4. In total, CAFD identified 47 different variants among 48 probands. Of these, 42 (89.36%, 42/47) were pathogenic, while 5 (10.64%, 5/47) were VUS. Sixteen (34.04%, 16/47) of the variants were novel, including 15 SNV/Indels and one large intronic insertion. Pedigree analysis of 21 probands identified four de novo disease-causing variants. Hence, FD exhibits not only variable clinical presentations but also a wide spectrum of variants. Utilizing a comprehensive testing algorithm for diagnosing FD, which includes enzyme activity, clinical features, and genetic testing, the diagnostic yield of CAFD is 97.92% (47/48), which is higher than that of conventional Sanger sequencing, at 95.83% (46/48).

CONCLUSION

The duration between initial clinical presentation and diagnosis remains long and winding. CAFD provides precise diagnosis for a wide spectrum of GLA variants, promoting timely diagnosis and appropriate treatment for FD patients.

The unlikely combination: Anderson-Fabry disease and congenital dyserythropoietic anemia type II in a pediatric patient

Key Clinical Message

Anderson-Fabry disease, a rare X-linked lysosomal disorder, and congenital dyserythropoietic anemia (CDA) Type II, an autosomal recessive condition, both have distinct inheritance patterns. Their co-occurrence is extremely rare, never been reported before. Therefore, screening is crucial for early management, and families should seek genetic counseling for children showing unusual presentations.

Abstract

Anderson-Fabry disease (AFD) is a rare condition, characterized by a lysosomal storage disorder affecting lipid storage. It manifests in two forms: classic (early-onset) and nonclassic (late-onset). Conversely, congenital dyserythropoietic anemia (CDA) is a rare blood disorder caused by ineffective erythropoiesis, which results in the production of abnormal erythroblasts during the maturation of red blood cells, with CDA type II being the most frequent type. Both disorders have well-understood pathophysiologies, yet they are genetically distinct. AFD is inherited in an X-linked manner, whereas CDA type II follows an autosomal recessive pattern of inheritance. Although both AFD and CDA type II have been reported separately in the literature. The co-existence for both AFD and CDA type II has not been reported. We describe a 10-year-old boy, with both which is believed to be the first documented case.

Concurrent fabry disease and immunoglobulin a nephropathy: a case report

BACKGROUND

Fabry disease (FD) is an X-linked, hereditary dysfunction of glycosphingolipid storage caused by mutations in the GLA gene encoding alpha-galactosidase A enzyme. In rare cases, FD may coexist with immunoglobulin A nephropathy (IgAN). We describe a case of concurrent FD, IgAN, and dilated cardiomyopathy-causing mutations in the TTN and BAG3 genes, which has not been reported previously.

CASE PRESENTATION

A 60-year-old female patient was admitted with a one-week history of facial and lower-limb edema, two-year history of left ventricular hypertrophy and sinus bradycardia, and recurring numbness and pain in three lateral digits with bilateral thenar muscle atrophy. Renal biopsy revealed concurrent FD (confirmed via an alpha-galactosidase A enzyme assay, Lyso-GL-3 quantification, and GLA gene sequencing) and IgAN. Heterozygous mutations in the TTN (c.30,484 C > A;p.P10162T) and BAG3 (c.88 A > G;p.I30V) genes were observed. The patient reported that two of her brothers had undergone kidney transplantation; one died suddenly at 60 years of age, and the other required a cardiac pacemaker. The 35-year-old son of the patient was screened for the GLA gene mutation and found to be positive for the same mutation as the patient. The patient was administered oral losartan (50 mg/day). Enzyme replacement therapy was refused due to financial reasons. Her renal and cardiac functions were stable yet worth closely monitoring during follow-up.

CONCLUSION

The family history of patients with concurrent heart and renal diseases should be assessed in detail. Genetic testing and histological examinations are essential for diagnosing FD with IgAN.

Rare presentation of Fabry disease as 'burnt-out' hypertrophic cardiomyopathy

We herein report the case of a 53-year-old man who was historically diagnosed with hypertrophic cardiomyopathy (HCM) and was lost to follow-up, before presenting with end-stage heart failure. This was initially suspected as dilated cardiomyopathy and then 'burnt-out phase' of HCM but subsequently the underlying diagnosis was Fabry disease. Fabry disease is an uncommon lysosomal-storage disease due to reduced or absent activity of the alpha-galactosidase A enzyme. Cardiac involvement most frequently comprises left ventricular hypertrophy. Early treatment of the underlying condition with enzyme replacement therapy may prevent the progression to end-stage heart failure. Fabry disease should be considered in all patients presenting with a clinical phenotype of HCM and a historical diagnosis should be re-evaluated in light of new diagnostic tools. Untreated Fabry can progress to a 'burnt out' phase, whereby initial hypertrophy undergoes eccentric remodelling to a dilated, severely impaired left ventricle.