Association between genes regulating neural pathways for quantitative traits of speech and language disorders

Specific Learning Disorders: Variation Analysis of 15 Candidate Genes in 9 Multiplex Families

Background and Objectives: Specific Learning Disorder (SLD) is a complex neurobiological disorder characterized by a persistent difficult in reading (dyslexia), written expression (dysgraphia), and mathematics (dyscalculia). The hereditary and genetic component is one of the underlying causes of SLD, but the relationship between genes and the environment should be considered. Several genetic studies were performed in different populations to identify causative genes. Materials and Methods: Here, we show the analysis of 9 multiplex families with at least 2 individuals diagnosed with SLD per family, with a total of 37 persons, 21 of whom are young subjects with SLD, by means of Next-Generation Sequencing (NGS) to identify possible causative mutations in a panel of 15 candidate genes: CCPG1, CYP19A1, DCDC2, DGKI, DIP2A, DYM, GCFC2, KIAA0319, MC5R, MRPL19, NEDD4L, PCNT, PRMT2, ROBO1, and S100B. Results: We detected, in eight families out nine, SNP variants in the DGKI, DIP2A, KIAA0319, and PCNT genes, even if in silico analysis did not show any causative effect on this behavioral condition. In all cases, the mutation was transmitted by one of the two parents, thus excluding the case of de novo mutation. Moreover, the parent carrying the allelic variant transmitted to the children, in six out of seven families, reports language difficulties. Conclusions: Although the present results cannot be considered conclusive due to the limited sample size, the identification of genetic variants in the above genes can provide input for further research on the same, as well as on other genes/mutations, to better understand the genetic basis of this disorder, and from this perspective, to better understand also the neuropsychological and social aspects connected to this disorder, which affects an increasing number of young people.

Evaluating the Association Between Genetically Proxied Neurodevelopmental Language Phenotypes and the Risk of Primary Progressive Aphasia

BACKGROUND AND OBJECTIVES

Primary progressive aphasia (PPA) is a neurodegenerative syndrome of progressive language decline. PPA has 3 main subtypes: logopenic, semantic, and agrammatic. Observational studies suggested an association between language-related neurodevelopmental phenotypes and an increased risk of PPA. We sought to assess such relationships through Mendelian randomization (MR) approach, which can suggest potentially causal associations.

METHODS

Genome-wide significant single-nucleotide polymorphisms (SNPs) associated with dyslexia (42 SNPs), developmental speech disorders (29 SNPs), and left-handedness (41 SNPs) were used as genetic proxies for the exposures. Eighteen of 41 SNPs of left-handedness were associated with structural asymmetry of the cerebral cortex. Genome-wide association study summary statistics were obtained from publicly available databases for semantic (308 cases/616 controls) and agrammatic PPA (269 cases/538 controls). The logopenic PPA (324 cases/3,444 controls) was approximated by proxy through the rubric of clinically diagnosed Alzheimer disease with salient language impairment. Inverse-weighted variance MR was performed as the main analysis for testing the relationship between the exposures and outcomes. Sensitivity analyses were completed to test the robustness of the results.

RESULTS

Dyslexia, developmental speech disorders, and left-handedness were not associated with any PPA subtype (p > 0.05). The genetic proxy of cortical asymmetry in left-handedness was significantly associated with agrammatic PPA (β = 4.3, p = 0.007), but not with other PPA subtypes. This association was driven by microtubule-related genes, primarily by a variant that is in complete linkage disequilibrium with MAPT gene. Sensitivity analyses were overall consistent with the primary analyses.

DISCUSSION

Our results do not support a causal association between dyslexia, developmental speech disorders, and handedness with any of the PPA subtypes. Our data suggest a complex association between cortical asymmetry genes and agrammatic PPA. Whether the additional association with left-handedness is necessary remains to be determined but is unlikely, given the absence of association between left-handedness and PPA. Genetic proxy of brain asymmetry (regardless of handedness) was not tested as an exposure due to lack of suitable genetic proxy. Furthermore, the genes related to cortical asymmetry associated with agrammatic PPA are implicated in microtubule-related proteins (TUBA1B, TUBB, and MAPT), which is keeping with the association of tau-related neurodegeneration in this PPA variant.

Genome-wide analysis of runs of homozygosity in Pakistani controls with no history of speech or language-related developmental phenotypes

BACKGROUND

Runs of homozygosity (ROHs) analysis of controls provide a convenient resource to minimize the association of false positive results of disease-associated ROHs and genetic variants for simple and complex disorders in individuals from the same population. Evidence for the value of ROHs to speech or language-related traits is restricted due to the absence of population-matched behaviourally defined controls and limited family-based studies.

AIM

This study aims to identify common ROHs in the Pakistani population, focussing on the total length and frequency of ROHs of variable sizes, shared ROHs, and their genomic distribution.

SUBJECTS AND METHODS

We performed homozygosity analysis (in PLINK) of 86 individuals (39 males, 47 females) with no history of speech or language-related phenotypes (controls) who had been genotyped with the Illumina Infinium QC Array-24.

RESULTS

ROHs of 1-<4 megabases (Mb) were frequent in unrelated individuals. We observed ROHs over 20 Mb among six individuals. Over 30 percent of the identified ROHs were shared among several individuals, indicating consanguinity's effect on the Pakistani population.

CONCLUSION

Our findings serve as a foundation for family-based genetic studies of consanguineous families with speech or language-related disorders to ultimately narrow the homozygosity regions of interest to identify pathogenic variants.

[Genetic aspects of speech disorders in children]

Speech disorders still remains one of the cornerstones of pediatric neurology. Against the backdrop of gene diagnostic development, there are a huge amount of information about the role of genetic and chromosomal abnormalities in pathogenesis of speech disorders. In present article authors presenting an actual data on genetic basis of different types of speech disorders. Moreover, authors describing a clinical case of a patient with genetically determined developmental disorder, caused by KMT5B mutation validated by Sanger method.

Differences and Commonalities in Children with Childhood Apraxia of Speech and Comorbid Neurodevelopmental Disorders: A Multidimensional Perspective

Childhood apraxia of speech (CAS) is a motor speech disorder often co-occurring with language impairment and complex neurodevelopmental disorders. A cohort of 106 children with CAS associated to other neurodevelopmental disorders underwent a multidimensional investigation of speech and language profiles, chromosome microarray analysis and structural brain magnetic resonance (MR). Our aim was to compare the clinical profiles of children with CAS co-occurring with only language impairment with those who, in addition to language impairment, had other neurodevelopmental disorders. Expressive grammar was impaired in the majority of the sample in the context of similar alterations of speech, typical of the core symptoms of CAS. Moreover, children with complex comorbidities also showed more severe and persistent receptive language deficits. About 25% of the participants harbored copy number variations (CNVs) already described in association to neurodevelopmental disorders. CNVs occurred more frequently in children with complex comorbidities. MR structural/signal alterations were found in a small number of children and were of uncertain pathogenic significance. These results confirm that CAS needs multidimensional diagnostic and clinical management. The high frequency of language impairment has important implications for early care and demands a personalized treatment approach in which speech and language goals are consistently integrated.

Oral and Laryngeal Diadochokinesis Across the Life Span: A Scoping Review of Methods, Reference Data, and Clinical Applications

PURPOSE

The aim of this study was to conduct a scoping review of research on oral and laryngeal diadochokinesis (DDK) in children and adults, either typically developing/developed or with a clinical diagnosis.

METHOD

Searches were conducted with PubMed/MEDLINE, Google Scholar, CINAHL, and legacy sources in retrieved articles. Search terms included the following: DDK, alternating motion rate, maximum repetition rate, sequential motion rate, and syllable repetition rate.

RESULTS

Three hundred sixty articles were retrieved and included in the review. Data source tables for children and adults list the number and ages of study participants, DDK task, and language(s) spoken. Cross-sectional data for typically developing children and typically developed adults are compiled for the monosyllables /pʌ/, /tʌ/, and /kʌ/; the trisyllable /pʌtʌkʌ/; and laryngeal DDK. In addition, DDK results are summarized for 26 disorders or conditions.

DISCUSSION

A growing number of multidisciplinary reports on DDK affirm its role in clinical practice and research across the world. Atypical DDK is not a well-defined singular entity but rather a label for a collection of disturbances associated with diverse etiologies, including motoric, structural, sensory, and cognitive. The clinical value of DDK can be optimized by consideration of task parameters, analysis method, and population of interest.