Polineuropatía por amiloidosis por transtiretina de inicio tardío. Caso clínico / Late-onset hereditary transthyretin amyloidosis with polyneuropathy. Report of one case

Hereditary transthyretin amyloidosis is a multisystemic autosomal dominant genetic disorder characterized by progressive distal sensory-motor polyneuropathy or restrictive cardiomyopathy, secondary to amyloid deposits. Its pathogenesis lies in the TTR gene mutation, and the Val50Met mutation is the most frequent. Patients have significant differences in the onset and severity of clinical presentation according to their country of origin. The diagnosis of this pathology is complex, even more in countries where it is not considered endemic. However, early suspicion and management are essential to improve survival and avoid unnecessary diagnostic and therapeutic strategies. We report a 69-year-old woman who presented a sensory-motor polyneuropathy, predominantly sensory, associated with distal neuropathic pain and bilateral vitritis. The history of her Italian father with polyneuropathy of unspecified etiology stood out. A vitreous biopsy identified amyloid substance deposits (congo red positive). These were also confirmed on a superficial peroneal nerve biopsy. During the etiological study of her polyneuropathy, an increased Kappa/Lambda index of 2.55 mg/L stood out. Therefore, light chain amyloidosis was suspected, and chemotherapy treatment was indicated without favorable response. After 10 years of progressive neurological and ophthalmological involvement, a genetic study confirmed the first case of late-onset hereditary transthyretin amyloidosis Val50Met with polyneuropathy in Chile.

AL amyloidosis in the Chilean public health system: a pending debt: multicenter study of the Chilean Monoclonal Gammopathies Cooperative Group / Amiloidosis AL en el sistema público de Chile: una deuda pendiente: estudio multicéntrico

ABSTRACT Background: Immunoglobulin light chain (AL) amyloidosis is a rare and underdiagnosed entity. Aim: To characterize patients with AL amyloidosis in Chilean public health centers. Material and Methods: We conducted a retrospective, multicenter study. Public centers of the Chilean Monoclonal Gammopathies Cooperative Group were asked to search for patients with AL amyloidosis in their databases. Epidemiological, clinical and laboratory characteristics were evaluated. Results: Forty-two patients aged 22 to 84 years were found. Twenty four percent had localized AL amyloidosis; 64% had a lambda light chain clone; 47% were associated with multiple myeloma and 9% with non-Hodgkin lymphoma. The most commonly involved organ was the kidney (76%). Serum free light chains were measured in 31% and an echocardiogram was performed in 74% of patients. Seventeen percent of patients received only palliative care, 17% were treated with bortezomib, 21% with thalidomide, and 40% with melphalan. No patient was transplanted. The mean overall survival (OS) of the group was 19 months. The 5-year OS was 28%. Conclusions: It is important to obtain these realistic, national data to initiate strategies to improve early diagnosis and proper management of this disease.

La amiloidosis AL es una entidad poco frecuente y subdiagnosticada. Mientras todo el mundo discute sobre las nuevas herramientas diagnósticas y terapéuticas, en Chile y en América Latina en general, estamos lejos de esa realidad. El objetivo del presente estudio fue caracterizar a los pacientes con amiloidosis AL en centros del sistema público de nuestro país. Se realizó un estudio retrospectivo, multicéntrico, descriptivo. Los centros públicos del grupo cooperativo hematológico chileno buscaron en sus bases de datos pacientes diagnosticados con amiloidosis AL. Se evaluaron las características epidemiológicas, clínicas y de laboratorio. La edad media fue de 65 años. A 24% de los pacientes se les diagnosticó amiloidosis AL localizada; 64% tuvo paraproteína con cadena ligera lambda; 47% se asoció con mieloma múltiple y 9% con linfoma no Hodgkin. El órgano afectado con mayor frecuencia fue el riñón (76%). Las cadenas ligeras libres de suero se realizaron en 31% y ecocardiograma en 74%. El 17% recibió solo cuidados paliativos, 17% recibió tratamiento con bortezomib, 21% con talidomida y 40% con melfalán. Ningún paciente fue trasplantado. La media de sobrevida global (SG) del grupo fue de 19 meses. La SG a 5 años fue de 28%. Es importante reportar estos resultados nacionales para iniciar estrategias que mejoren tanto el diagnóstico temprano como el tratamiento de esta patología. Por lo tanto, mejorar la sospecha diagnóstica es crucial.