Estimating the relative frequency of leukodystrophies and recommendations for carrier screening in the era of next‐generation sequencing

Leukodystrophies are a heterogeneous group of heritable disorders characterized by abnormal brain white matter signal on magnetic resonance imaging (MRI) and primary involvement of the cellular components of myelin. Previous estimates suggest the incidence of leukodystrophies as a whole to be 1 in 7,000 individuals, however the frequency of specific diagnoses relative to others has not been described. Next generation sequencing approaches offer the opportunity to redefine our understanding of the relative frequency of different leukodystrophies. We assessed the relative frequency of all 30 leukodystrophies (associated with 55 genes) in more than 49,000 exomes. We identified a relatively high frequency of disorders previously thought of as very rare, including Aicardi Goutières Syndrome, TUBB4A‐related leukodystrophy, Peroxisomal biogenesis disorders, POLR3‐related Leukodystrophy, Vanishing White Matter, and Pelizaeus‐Merzbacher Disease. Despite the relative frequency of these conditions, carrier‐screening laboratories regularly test only 20 of the 55 leukodystrophy‐related genes, and do not test at all, or test only one or a few, genes for some of the higher frequency disorders. Relative frequency of leukodystrophies previously considered very rare suggests these disorders may benefit from expanded carrier screening.     

Haplotypes produced from rare variants in the promoter and coding regions of angiotensinogen contribute to variation in angiotensinogen levels

The most efficient study design to map genes underlying complex traits will be determined by assumptions about whether the genetic effects are likely to be due to relatively few common variants or multiple rare variants. To examine the possibility that rare variants may influence blood pressure, we sequenced a 6.8 kb region of the angiotensinogen (AGT) gene in 29 male Nigerians with high plasma AGT levels and 28 with low levels. The frequency of haplotypes produced from rare variants in the promoter and coding regions was significantly different between the two groups, and it is unlikely that this difference was due to the manner in which the rare variants were selected. Further analysis suggested that most of the haplotypes produced by these rare variants are found on a haplotype background created by three common SNPs. Our study confirms in an additional trait that rare variants can influence the distribution of complex traits; whether these variants can be captured by common SNPs or haplotypes requires further investigation.     

Comparison of complement fixation and hemagglutination inhibition assays for detecting antibody responses following influenza virus vaccination

Complement fixation (CF) was compared to hemagglutination inhibition (HI) as a method for identifying antibody responses to influenza virus vaccination. CF assays were performed at two different laboratories using paired (pre- and postvaccination) sera from 38 vaccinated laboratory employees; HI assays were performed at a third laboratory. As expected, most vaccinees (31/38 = 82%) responded to at least one of three influenza virus antigens as measured by HI. In contrast, only 21% (8/38) of vaccinees showed a response by CF at laboratory 1, and only 29% (11/38) showed a response by CF at laboratory 2. These findings indicate that due to low sensitivity, CF assays should not be used to assess the antibody response to influenza virus vaccination.     

Myocardial disease and catecholamine metabolism in JCR:LA-corpulent rat

The JCR:LA-cp rat is a strain carrying the mutant cp (corpulent) gene. Animals that are homozygous cp are hyperphagous, hyperinsulinemic, hyperlipidemic, and obese. Corpulent male rats, but not females or lean rats, develop atherosclerotic lesions and myocardial lesions. Since the myocardial lesions are apparently of ischemic origin, the noradrenergic system and vascular hyperactivity and vasospasm may play a role in the pathogenesis. To test this we have studied the brain contents of the amines norepinephrine, dopamine, and 5-hydroxtryptamine and their breakdown products and depleted the peripheral sympathetic terminals with 6-hydroxydopamine. Only 5-hydroxytryptamine and 5 hydroxyindole-3-acetic acid were present at higher concentrations in the corpulent rats with depressed levels of dopamine in very young or old lean rats. The activity of monoamine oxidase may provide an indication of nonadrenergic activity in tissue. The activity in the heart increased with age and was higher in the corpulent rats than in the lean at all ages. Activity in aorta was independent of age or genotype. Long term treatment with 6-hydroxydopamine caused marked depletion of norepinephrine in the heart with only a slight decrease in brain concentration. There were no effects on the hyperlipidemia or hyperinsulinemia that are strongly associated with vascular and myocardial disease. The myocardial lesion frequency in corpulent rats was not altered by the chemical sympathectomy. The results suggest that norepinephrine and the sympathetic nervous system are probably not involved in the generation of the myocardial lesions or metabolic abnormalities in this strain of rat.     

Examining Trichophyton tonsurans genotype and biochemical phenotype as determinants of disease severity in tinea capitis.

Trichophyton tonsurans infections occur in various host populations, on various body sites and with varying degrees of inflammation. This investigation was undertaken to determine whether fungal factors could explain the degree of severity in clinical symptomatology among infected children. Otherwise healthy children (n=54) presenting with tinea capitis were enrolled in this study. A thorough history was performed, the extent and severity of infection graded and a fungal specimen collected from each child. Strain type was determined by genotyping for 11 sequence variations in the rDNA and ALP1 loci. Secreted protease activity was quantitated after 5 days of growth in aqueous medium. Forty participants were evaluable. Infection duration ranged from 1 day to 3 years and clinical severity score (CSS) from 4-19. Seventeen unique fungal genotypes were present. Keratinase, collagenase and elastase activity varied 32.7-fold, 64.9-fold and 303.3-fold, respectively. A significant association was observed between genotype and disease severity with the rDNA sequence variations accounting for over 50% of the variation observed in CSS (r2=0.539; P<0.001). Phylogenetic analyses appear to suggest that the ancestral strain types of T. tonsurans cause more severe disease. These observations are consistent with reports that recently diverge anthropophilies are associated with diminished inflammatory involvement.     

Quality of life profiles and their association with clinical and demographic characteristics and physical activity in people with a stoma: a latent profile analysis

Quality of Life Research - Quality of life can be negatively impacted by the formation of a stoma and is influenced by a number of factors. Research to date treats people with a stoma as a...     

Short-term impact of COVID-19 on quality of life,perceived stress,and serious psychological distress in an adult population in the midwest United States

Quality of Life Research - This study aimed to investigate changes over time in quality of life, perceived stress, and serious psychological distress for individuals diagnosed with COVID-19 in an...     

Primary social factors and smoking in Korean adolescents

Journal of Public Health - The present study aimed to examine the effects of primary social factors on the smoking behaviors according to the smoking stages—initiation and...