Health problems in females carriers of premutation in the FMR1 gene

Premutation in the FMR1 gene occur in the general population with an estimated prevalence 1 in 130-260 females and 1 in 250-810 males. Carriers of premutation are at risk of development of spectrum of neurological, psychiatric and immunological disorders in adulthood. Fragile X-associated disease caused by dynamic mutation (expansion of CGG repeats) can be divided into three disorders: FXS - Fragile X syndrome, FXPOI - Fragile X-associated primary ovarian insufficiency, FXTAS -Fragile X-associated tremor/ataxia syndrome, which can be present in few generations of one family. Immuno-mediated disorders are more common in premutation carriers as compared to control group, especially hypothyroidism and fibromyalgia. Although FMR1-associated conditions are not curable, timely diagnosis through genetic testing is important as it can lead to implementation of treatment strategies and behavioral interventions considered to improve symptoms. Knowledge of expanded allele status for females helps them to make more informed reproductive decisions.

Plasma Levels of Leptin and Adiponectin in Fragile X Syndrome

Fragile X syndrome (FXS) is the most common form of familial mental retardation and one of the leading known causes of autism. The mutation responsible for FXS is a large expansion of the CGG repeats in the promoter region of the FMR1 gene, resulting in the transcriptional silencing of the gene. Leptin may be considered a cytokine-like hormone with pleiotropic actions since it may be involved in the regulation of neuroendocrine functions and the immune system response, in addition to playing a role in development. Leptin and adiponectin may act in parallel as opposing metabolic counterparts. The involvement of leptin and adiponectin in the pathophysiology of FXS was hypothesized.

MATERIAL AND METHODS

Twenty-three male patients affected by FXS (full mutation in the FMR1 gene) and 24 controls were included in the study. Plasma leptin and adiponectin levels were measured by the ELISA method using commercially available kits.

RESULTS

Adiponectin levels in FXS patients were significantly lower than those found in controls (p < 0.04). Leptin levels in FXS patients were significantly higher than those found in controls (p = 0.03).

CONCLUSION

Adipokines may be involved in the psychiatric features observed in FXS patients. Further investigations are necessary to evaluate the role of adiponectin and leptin in FXS.

Anti-neuronal antibodies in patients with fragile X syndrome: is there a role of autoimmunity in its pathogenesis?

BACKGROUND

Fragile X syndrome (FXS) is a single-gene disorder with a broad spectrum of involvement, including cognitive and behavioural impairments of varying degrees with specific physical features and a strong association with autism.

OBJECTIVES

In this study, the frequency of serum anti-neural antibodies was investigated in FXS patients who did and those who did not manifest autism spectrum disorders (ASD) in comparison to typically developing controls.

METHODS

The study involved 23 males (mean age, 19.78 ± 6.56 years) who harboured a full mutation in the FMR1 gene. The control group comprised 19 healthy students (mean age 24.63 ± 1.89 years). Serum anti-neuronal antibodies were analyzed using Western blotting.

RESULTS

Serum anti-neuronal antibodies were present in 10/23 (43.48%) FXS males.

CONCLUSION

Serum anti-neuronal antibodies were found in a subgroup of FXS patients. Autistic symptoms in FXS may, in part, be caused by auto-immune factors. Further studies in larger patient and control groups are necessary to elucidate the aetiopathogenic role of anti-neuronal antibodies in FXS patients.

X-linked mental retardation

Mental retardation is a serious medical and social problem. The prevalence of mental retardation in Western countries is estimated to be between 2 and 3%. Establishing the cause of mental retardation is essential for prognosis, management, and genetic counseling. It is estimated that 25-35% of mental retardation might have a genetic background. Of these genetic causes, 25-30% are probably due to mutations on the X chromosome (X-linked mental retardation, XLMR). XLMR is a heterogeneous set of conditions involved in a large proportion of inherited mental retardation. More than 200 XLMR conditions have been reported and 76 genes has been linked to them. XLMR conditions are commonly subdivided into syndromic and nonsyndromic forms on the basis of clinical presentation. The distinction between these forms of XLMR is gradually becoming less clear as phenotypes are described for several of the genes. The spectrum of phenotypic variability in XLMR is so large that mutations in several XLMR genes have been found in both syndromic and nonsyndromic (XLMR) pedigrees. About 42% of patients from families with an XLMR history might have mutations in one of the known genes implicated in XLMR. However, in genetic counseling we have to use empiric recurrence risk.