BackgroundNeurologic impairments in female heterozygotes for X-linked Adrenoleukodystrophy (X-ALD) are poorly understood. Our aims were to describe the neurological and neurophysiological manifestations of a cohort of X-ALD heterozygotes, and to correlate them with age, disease duration, mutations, X-inactivation and serum concentrations of a marker of neuronal damage, neuron-specific enolase (NSE).MethodsAll 45 heterozygotes identified in our region, with previous VLCFA and molecular diagnosis, were invited to be evaluated through myelopathy scales JOA and SSPROM, nerve conduction studies and somatosensory evoked responses. X inactivation pattern was tested by HUMARA methylation assay. Serum NSE was measured by eletrochemiluminescense.ResultsThirty three heterozygote women were recruited: 29 (87%) were symptomatic. Symptomatic and asymptomatic women presented different m ± sd ages (43.9 ± 10.2 versus 24.3 ± 4.6), JOA (14.5 ± 1.7 versus 16.6 ± 0.2) and SSPROM (86.6 ± 7.9 versus 98.4 ± 1.1) scores (p < 0.05). Both JOA (r = −0.68) and SSPROM (r = −0.65) correlated with age, irrespectively of the disease status (p = 0.0001, Spearman). Delayed latencies in the central ascending conduction studies on the lower limbs were present in 72% of all heterozygotes, and correlated with SSPROM (r = −0.47, p = 0.018, Spearman). NSE values were higher in heterozygote than in control women (12.9 ± 7 and 7.2 ± 7 ng/ml, p = 0.012, Mann-Whitney U). Mutation severity and inactivation patterns were not associated with neurologic status.ConclusionNeurologic manifestations, clearly related to age, were quite common in the present cohort. JOA and SSPROM scales were able to discriminate the asymptomatic from the symptomatic heterozygotes. Both scales might be useful tools to follow disease progression, in future studies.
In this study, we analyzed the ABCD1 gene in X-linked adrenoleukodystrophy (X-ALD) patients and relatives from 38 unrelated families from South America, as well as phenotypic proportions, survival estimates, and the potential effect of geographical origin in clinical characteristics. Methods X- ALD patients from Brazil, Argentina and Uruguay were invited to participate in molecular studies to determine their genetic status, characterize the mutations and improve the genetic counseling of their families. All samples were screened by SSCP analysis of PCR fragments, followed by automated DNA sequencing to establish the specific mutation in each family. Age at onset and at death, male phenotypes, genetic status of women, and the effect of family and of latitude of origin were also studied. Results We identified thirty-six different mutations (twelve novel). This population had an important allelic heterogeneity, as only p.Arg518Gln was repeatedly found (three families). Four cases carried de novo mutations. Intra-familiar phenotype variability was observed in all families. Out of 87 affected males identified, 65% had the cerebral phenotype (CALD). The mean (95% CI) ages at onset and at death of the CALD were 10.9 (9.1–12.7) and 24.7 (19.8–29.6) years. No association was found between phenotypic manifestations and latitude of origin. One index-case was a girl with CALD who carried an ABCD1 mutation, and had completely skewed X inactivation. Conclusions This study extends the spectrum of mutations in X-ALD, confirms the high rates of de novo mutations and the absence of common mutations, and suggests a possible high frequency of cerebral forms in our population.
X-linked adrenoleukodystrophy heterozygote women can present adult onset myeloneuropathy and little is known about its natural history. We aimed to describe the progression rate of the neurological impairment in the prospective follow-up of our cohort and to look for prognostic factors. The neurological scales Japanese Orthopaedic Association (JOA) and Severity Score System for Progressive Myelopathy (SSPROM) were applied at baseline in 29 symptomatic carriers and in follow-up visits. Age at onset, disease duration, X inactivation pattern, determination of the allele expressed, plasma levels of the very long chain fatty acids and of the neuron-specific enolase, and somato-sensory evoked potentials, were taken at baseline. The slope of the linear regression of both JOA and SSPROM versus disease duration since the first symptom was estimated using mixed modeling. JOA and SSPROM decreased 0.42 and 1.87 points per year, respectively (p < 0.001). None of the parameters under study influenced these rates. We estimated that the number of carriers per arm needed in a future 12 month trial with 80% power and a 50% reduction in disease progression would be 225 women for JOA and 750 for SSPROM. The progression rates of the studied neurological scales were small, did not depend on any modifier factor known, and reflected the characteristically slow worsening of symptoms in X-ALD heterozygotes. Better biomarkers are still necessary for future studies.
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