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Neurological disorders (ND) are diseases that affect the brain and the central and autonomic nervous systems, such as neurodevelopmental disorders, cerebellar ataxias, Parkinson’s disease, or epilepsies. Nowadays, recommendations of the American College of Medical Genetics and Genomics strongly recommend applying next generation sequencing (NGS) as a first-line test in patients with these disorders. Whole exome sequencing (WES) is widely regarded as the current technology of choice for diagnosing monogenic ND. The introduction of NGS allows for rapid and inexpensive large-scale genomic analysis and has led to enormous progress in deciphering monogenic forms of various genetic diseases. The simultaneous analysis of several potentially mutated genes improves the diagnostic process, making it faster and more efficient. The main aim of this report is to discuss the impact and advantages of the implementation of WES into the clinical diagnosis and management of ND. Therefore, we have performed a retrospective evaluation of WES application in 209 cases referred to the Department of Biochemistry and Molecular Genetics of the Hospital Clinic of Barcelona for WES sequencing derived from neurologists or clinical geneticists. In addition, we have further discussed some important facts regarding classification criteria for pathogenicity of rare variants, variants of unknown significance, deleterious variants, different clinical phenotypes, or frequency of actionable secondary findings. Different studies have shown that WES implementation establish diagnostic rate around 32% in ND and the continuous molecular diagnosis is essential to solve the remaining cases.

Purpose: Routine protocols for the study of mental retardation include karyotype, analysis for fragile X syndrome, and subtelomeric rearrangements. Nevertheless, detection of cryptic rearrangements requires more sensitive techniques. Mutation screening in all known genes responsible for X-linked mental retardation is not feasible, and linkage analysis is sometimes limited. Multiplex ligation probe amplification is a recently developed technique based on the amplification of specific probes that allows relative quantification of 40 to 46 different target DNA sequences in a single reaction. Methods: In the present study, we assessed multiplex ligation probe amplification for the detection of microduplications/microdeletions in 80 male patients with suspicion of X-linked mental retardation. Results: We detected four copy number aberrations (5%): three duplications (GDI1, RPS6KA3, and ARHGEF6) and one deletion (OPHN1). All these changes were confirmed by other molecular techniques, and patients were clinically re-evaluated. Conclusions: We strongly recommend the use of multiplex ligation probe amplification as a first screening method for the detection of copy number aberrations in patients with mental retardation because of its cost-effectiveness.

The SOX5 gene encodes a transcription factor involved in the regulation of chondrogenesis and the development of the nervous system.We report a 10 years-old girl with developmental delay, behavior problems and dysmorphic features of this new syndrome with developmental delay. She had a 12p12 deletion involving SOX5.We review the reported cases, intragenic SOX5 deletions and larger 12p12 deletions encompassing SOX5. We analyze the genotype-phenotype associations and the genes involved in our patient.Microdelecion 12p12 que incluye el gen SOX5: un nuevo sindrome con alteracion del neurodesarrollo.Introduccion. El gen SOX5 codifica un factor de transcripcion implicado en la regulacion de la condrogenia y el desarrollo del sistema nervioso. Caso clinico. Niña de 10 anos con discapacidad intelectual, alteracion conductual y malformaciones menores de este nuevo sindrome con alteracion en el neurodesarrollo, con una delecion 12p12 que incluye el gen SOX5. Conclusiones. Se revisan los casos publicados tanto de deleciones intragenicas de SOX5 como de deleciones mas grandes que incluyen este gen, y se analizan las correlaciones genotipo-fenotipo y los genes implicados en esta paciente.

It has been estimated that 1:1233 males and 1:411 females are FMR1 premutated carriers. This gene is responsible for the fragile X syndrome.Among 398 fragile X syndrome families, we evaluated 112 premutated carriers older than 50 year.FXTAS penetrance among fragile X families was 10.7% for female premutated carriers and 29.7% for male premutated carriers. In the general population, it was estimated that 1:4,000 females and 1:5,000 males will develop the FXTAS syndrome.Besides the risk for fragile X syndrome, the genetic counseling in premutation carriers should mention the risk for FXTAS. This syndrome should also be taken into account among spinocerebelar ataxia patients with an unknown etiology.