Aim We propose to estimate the prevalence of Fabry disease among diagnosed hypertrophic dilated cardiomyopathy (HCM) and unexplained left ventricular hypertrophy (LVH) patients attending St. James Hospital between 2013–2015.
Methods Patients invited from cardiology outpatients department (OPD) and implantable cardiac defibrillator (ICD) clinic for screening. Ongoing search for new patients diagnosed with HCM and LVH via echo report, cardiac MRI, device implantation list and from OPD list. A database created. When patients arrived, they are informed regarding Fabry disease, manifestation and implications of having this test and consented for blood testing. Fabry disease symptoms and signs survey form were also completed along family pedigree. Blood samples obtained and bar coded for traceability in the local laboratory and sent via courier to Royal Free Hospital within 72 hours. If the results were positive they were called to clinic for further discussion regarding the implications and will be referred to a metabolic consultant in Mater Misericordiae University Hospital and for nephrology consultant for renal assessment in St. James Hospital. If the blood test were negative they were informed over the phone and letter sent to patient, their general practice (GP) and a copy inserted into their chart. Results were entered into excel spreadsheet and SPSS programmer for analysis.
Results 126 patients with diagnosis of HCM and LVH patients invited to have blood test for Fabry disease. Only 70 (60%) accepted the offer and had the blood test performed. Male patients (63%) had enzyme levels analysis; meanwhile female patients (37%) had enzyme level and DNA analysis specific for Fabry disease. Of the 70 patients, mean age was 52 ± 16 years old, 90% had diagnosis of HCM and 10% had unexplained LVH. Four percent (1 male and 2 female) patients of screened patient has been diagnosed Fabry disease. The prevalence of our cohort study was 4%. One of the diagnosed male patient who has renal impairment had been commenced on Fabraenzyme therapy. One female patient who has renal impairment refused the treatment and the third patient who has eGFR 67 ml/l undergoing assessment from nephrologist and a metabolic consultant specialist. Interestingly we also noted that there were five (three female and further two male) patients noted to have intronic mutations. One of the five patient who had HCM with obstructive features, had lower range of enzyme level. He had patchy late gadolinium enhancement and estimated eGFR 70 ml/min, lower than expected for his age. DNA analysis done which showed two intronic mutations noted and he was diagnosed as late onset Fabry disease and the prevalence in our population rises up to 6%. He was referred for suitability assessment for enzyme replacement therapy.
Conclusion Fabry disease is still a rare genetic disorder, the prevalence in our population is about 6%. Intronic mutations are less understood. This raises question whether everyone should have full DNA analysis regardless of the gender. It is treatable disease with enzyme therapy to herald major late complications. It should be routinely used to screen patients presenting with HCM and unexplained LVH.
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