Kennedy Disease in Latin America: Two New Mexican Cases and a Systematic Review of Regional Reports.

Spinal and bulbar muscular atrophy (SBMA), or Kennedy disease (KD), is a rare X-linked trinucleotide repeat disorder caused by cytosine, adenine, and guanine (CAG) expansions in the androgen receptor (AR) gene. KD affects lower motor neurons, leading to progressive muscle weakness, bulbar dysfunction, and endocrine symptoms such as gynecomastia. Diagnosis is challenging due to phenotypic overlap with other neurodegenerative diseases. This report aimed to describe two new Mexican cases of KD and to summarize all published cases of KD in Latin America through a systematic review (SR). The SR search was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method in the Scielo, Lilacs, and Scopus databases, including cohort studies, case series, and case reports with molecular confirmation of SBMA. Clinical and molecular data were analyzed. The review identified 23 Latin American SBMA cases. The median age of onset was 43 years (range: 21-66). The most common manifestations were weakness (95.7%; n = 22), tremor (65.2%; n = 15), and bulbar symptoms such as dysarthria (95.6%; n = 22) and dysphagia (91.3%; n = 21). Endocrine manifestations such as gynecomastia (73.9%; n = 17) and sexual dysfunction (56.5%; n = 13) were common. Electrophysiological findings confirmed lower motor neuron involvement, and molecular analysis revealed a median of 46.5 CAG repeats. Despite its low frequency, SBMA remains underdiagnosed in Latin America, which may be due to limited awareness and clinical overlap with other pathologies. Molecular testing is crucial for diagnostic certainty. The review also highlights the need to evaluate multisystem involvement. Improved diagnostic protocols, genetic counseling, and increased awareness are needed for the timely detection and management of SBMA in Latin America.