Functional genomics provide key insights to improve the diagnostic yield of hereditary ataxia

Improvements in functional genomic annotation have led to a critical mass of neurogenetic discoveries. This is exemplified in hereditary ataxia, a heterogeneous group of disorders characterised by incoordination from cerebellar dysfunction. Associated pathogenic variants in more than 300 genes have been described, leading to a detailed genetic classification partitioned by age-of-onset. Despite these advances, up to 75% of patients with ataxia remain molecularly undiagnosed even following whole genome sequencing, as exemplified in the 100,000 Genomes Project. This study aimed to understand whether we can improve our knowledge of the genetic architecture of hereditary ataxia by leveraging functional genomic annotations, and as a result, generate insights and strategies that raise the diagnostic yield. To achieve these aims, we used publicly-available multi-omics data to generate 294 genic features, capturing information relating to a gene's structure, genetic variation, tissue-specific, cell-type-specific and temporal expression, as well as protein products of a gene. We studied these features across genes typically causing childhood-onset, adult-onset or both types of disease first individually, then collectively. This led to the generation of testable hypotheses which we investigated using whole genome sequencing data from up to 2,182 individuals presenting with ataxia and 6,658 non-neurological probands recruited in the 100,000 Genomes Project. Using this approach, we demonstrated a high short tandem repeat (STR) density within childhood-onset genes suggesting that we may be missing pathogenic repeat expansions within this cohort. This was verified in both childhood- and adult-onset ataxia patients from the 100,000 Genomes Project who were unexpectedly found to have a trend for higher repeat sizes even at naturally-occurring STRs within known ataxia genes, implying a role for STRs in pathogenesis. Using unsupervised analysis, we found significant similarities in genomic annotation across the gene panels, which suggested adult- and childhood-onset patients should be screened using a common diagnostic gene set. We tested this within the 100,000 Genomes Project by assessing the burden of pathogenic variants among childhood-onset genes in adult-onset patients and vice versa. This demonstrated a significantly higher burden of rare, potentially pathogenic variants in conventional childhood-onset genes among individuals with adult-onset ataxia. Our analysis has implications for the current clinical practice in genetic testing for hereditary ataxia. We suggest that the diagnostic rate for hereditary ataxia could be increased by removing the age-of-onset partition, and through a modified screening for repeat expansions in naturally-occurring STRs within known ataxia-associated genes, in effect treating these regions as candidate pathogenic loci.

A study of the discomfort associated with tennis shoes

Subjective tests based on information gathered using 'discomfort questionnaires' have been used widely in ergonomics. In this study, we used a similar method to examine the discomfort associated with the footwear worn in tennis matches. A sample of 146 tennis players from a population of approximately 4000 completed the questionnaire. We performed a descriptive analysis of the study variables. The associations between discomfort and pain and between discomfort and design errors were evaluated using cross-tabulation and chi-squared tests. We found that 9% of players considered their footwear to be uncomfortable, 23% considered it to be acceptable and 68% regarded it as comfortable. Six design errors were identified and five body areas were reported as experiencing discomfort due to the footwear. Factor analysis identified four factors related to discomfort and six design errors. Subsequent correlation analysis identified several relationships among these factors. There was a strong correlation (r = 0.187, P = 0.022) between plantar discomfort and incorrect arch support.

Idiopathic chondrolysis of the hip: long-term evolution

Idiopathic chondrolysis of the hip is characterized by the destruction of the articular cartilage due to an unknown cause, principally affecting women during adolescence and producing premature degeneration of the hip. Twelve cases (11 patients) were reviewed at our hospital, with an average follow-up period of 13.2 years, during which a clinical and radiologic study was performed. Despite the treatment implemented, idiopathic chondrolysis of the hip causes progressive degeneration of the joint with the appearance of almost constant pain, stiffness, and anomalous positions. Radiologic studies show concentric narrowing of the articular space, decrease in the width of the femoral head and neck, and shortening of the affected member due to alteration in the growth physis of the upper extremity of the femur.

Properties of shoe insert materials related to shock wave transmission during gait

The influence of the mechanical characteristics of certain insole materials in the generation and transmission of heel strike impacts while walking was studied. Three insole materials were selected according to their mechanical characteristics under heel strike impacts. The selection of materials has made it possible to distinguish the effect of rigidity and loss tangent in the transmission of heel strike impacts. A lower rigidity and a high loss tangent have been shown to reduce the transmission of impacts to the tibia. A low rigidity was seen to significantly increase the transmission of impacts from tibia to forehead.

Dynamic study of insole materials simulating real loads

A new methodology of biomechanical analysis of materials for shoe inserts is presented. This methodology is based on the determination of the loads applied to the materials in real situations and its simulation by means of a dynamic testing machine. Both the rigidity and the energy-absorbing characteristics of the materials are investigated as a function of frequency. This methodology is applied to the study of several commercially available viscoelastic materials intended for shoe inserts in the treatment and prevention of degenerative joint diseases. The influence of thickness is investigated as well as the frequency-dependent behavior of the materials studied. Significant differences between materials and different behavior as a function of thickness and frequency were found. Poron materials were found to have the lowest rigidity, good for adequate pressure distribution, while Noene showed the highest energy absorption. A careful selection of the thickness of Sorbothane was found to be necessary for avoiding flattening of the material.