Is lower urinary tract dysfunction an early marker of Portuguese type familial amyloidotic polyneuropathy in women? Preliminary results.

ABSTRACT

Type 1 Portuguese Familial Amyloid Polyneuropathy was first observed in 1939 and described in 1951 by Corino Andrade. FAP is a rare autosomal dominant disease caused by a mutant gene in chromosome 18, characterized by a variant transthyretin in which valine is substituted for methionine at position 30 (ATTR V30M), affecting mainly young adults. ATTR V30M positivity does not imply disease, but the disease is only present with ATTR V30M in serum. The clinical manifestations of FAP on the pelvic floor and genitourinary system are frequent at early disease onset. Phenotypic diversity can depend on modulating agents in the deposition of the mutant TTR, such as incomplete penetration and environmental influence. Functional vesicourethral disorders appear to be primarily at the bladder filling phase, namely diminished bladder sensation, and associated with a decrease in detrusor contractility during the emptying phase. Unbalanced voiding takes place in this context, with high post-void residuals, increasing the rate of co-morbidity, namely recurrent urinary tract infections and chronic renal failure.This study describes the lower urinary tract dysfunctions in ATTR V30M positive carriers, particularly during the asymptomatic period and early stages of the disease, and additionaly it describes its association with the clinical evolution of the disease. In the preliminary phase of the study, the lower urinary tract dysfunction in FAP-women may present itself as an early manifestation in asymptomatic patients. Uroflowmetry and the evaluation of post-voiding residual volume are non-invasive and low cost tests that should be done during routine initial evaluation. Reduced bladder sensation and poor detrusor contractility may be considered initial markers of FAP. The neurogenic factor (bladder afferent neurons) appears to be mechanical in nature with myogenic repercussions. This further aggravates the bladder underactivity secondary to pelvic efferent parasympathetic neuropathy and amyloid infiltration in the bladder wall. Early diagnostic and therapeutic intervention may avoid secondary end stage renal disease.