ATXN1 intermediate-length polyglutamine expansions are associated with amyotrophic lateral sclerosis.

To clarify the possible involvement of intermediate ATXN1 alleles as risk factors for amyotrophic lateral sclerosis (ALS), we tested ATXN1 in a cohort of 1146 Italian ALS patients, previously screened for variants in other ALS genes, and in 529 controls. We detected ATXN1 alleles with ≥33 polyglutamine repeats in 105 of 1146 patients (9.16%) and 29 of 529 controls (5.48%) (p = 0.003). The frequency of ATXN1 alleles with ≥33 polyglutamine repeats was particularly high in the group of ALS patients carrying the C9orf72 expansion (12/59, 20.3%). We confirmed this result in an independent cohort of C9orf72 Italian patients (10/80 cases, 12.5%), thus finding a cumulative frequency of ATXN1 expansion of 15.82% in C9orf72 carriers (p = 2.40E-05). Our results strongly support the hypothesis that ATXN1 could act as a disease risk gene in ALS, mostly in C9orf72 expansion carriers. Further studies are needed to confirm our results and to define the mechanism by which ATXN1 might contribute to neuronal degeneration leading to ALS.

Pareto versus lognormal: a maximum entropy test.

It is commonly found that distributions that seem to be lognormal over a broad range change to a power-law (Pareto) distribution for the last few percentiles. The distributions of many physical, natural, and social events (earthquake size, species abundance, income and wealth, as well as file, city, and firm sizes) display this structure. We present a test for the occurrence of power-law tails in statistical distributions based on maximum entropy. This methodology allows one to identify the true data-generating processes even in the case when it is neither lognormal nor Pareto. The maximum entropy approach is then compared with other widely used methods and applied to different levels of aggregation of complex systems. Our results provide support for the theory that distributions with lognormal body and Pareto tail can be generated as mixtures of lognormally distributed units.

Influence of anterior tooth alignment on peer perception in 8- to 10-year-old children.

The purpose of this research was to investigate whether anterior dental alignment in 8- to 10-year-old children influences the first impressions of their peers, and to verify the validity of the tested method. From colour photographs of two attractive children, one male and one female, Adobe Photoshop 5.0 was used to alter the images and create three versions of each photograph: one with good anterior dental alignment (OK smile), a second with proclination of the upper incisors (P-type smile), and finally one with moderate-to-severe anterior crowding (C-type smile). The six different photographs were shown to 121 subjects with mean age of 9.2 years (65 females and 56 males). Each subject was asked to view one photograph and subsequently respond to a questionnaire, the 'Smile perception questionnaire for children between the ages of 8 and 10' (SPQ 8-10), composed of 13 questions with graded responses. The responses for each photograph were analysed using linear regression analysis to determine the questionnaires validity as a whole and to investigate five area of common interest (honesty, intelligence, personal happiness, pleasantness, and extroversion). The results demonstrated that the questionnaire was reliable both from an internal coherence standpoint and from a test-retest reliability perspective. Data regarding the five areas of interest showed that 8- to 10-year-olds viewed their peers with well-aligned teeth more favourably as far as honesty, personal happiness, and intelligence were concerned. However, there was no statistically significant difference with regard to pleasantness and extroversion in children with harmonious, as opposed to crowded or proclined anterior teeth.

Dental arch changes following rapid maxillary expansion.

The purpose of this research was to evaluate changes in upper arch dimension and form following rapid maxillary expansion (RME) using a modified Haas appliance in the primary dentition. The sample comprised 49 children [17 males, 32 females, mean age 7 years 5 months, standard deviation (SD) 1 year 1 month] with a crossbite or maxillary crowding. Twenty patients had a normal SN-GoGn angle (7 males, 13 females, mean 33.25 degrees, SD 2.10), three were low angle (1 male, 2 females, mean 27.67 degrees, SD 2.31), and 22 were high angle (8 males, 14 females, mean 39.95 degrees, SD 3.15). The vertical dimensions of four patients could not be measured, due to the unavailability of radiographs. Expansion was undertaken to either correct a crossbite or treat maxillary crowding. The upper dental casts were analysed using a computerized system: before treatment (T1), at appliance removal (T2), and 2 years 4 months after appliance removal (T3). Using bootstrap statistical analysis applied to distance ratio values [Euclidean distance matrix analysis (EDMA)], it was found that 48 patients showed a change in arch form. In 40.82 per cent (n = 20, group A), the arch form changed from T1 to T2, T1 to T3, and T2 to T3. In 32.65 per cent (n = 16, group B), it varied from T1 to T2 but relapsed at T3 to the form of T1. For 24.5 per cent (n = 12, group C), it changed from T1 to T2 but maintained the same form at T3. The favourable characteristics for obtaining expansion, identified by logistic regression analysis, were being male, of an immature stage of dental development (lateral incisor not fully erupted) and the presence of a lateral crossbite. Intercanine and intermolar widths, arch length, and the distance between the interincisive point and the line joining the canines (depth of the intercanine arch) at the different time points were analysed using a two-tailed t-test (P < 0.05). For the whole group, the increase in intercanine and intermolar width and in the depth of the intercanine arch was significant. Comparison between groups A, B, and C was undertaken using an analysis of variance, but there was no significant difference between the groups. This modified type of Haas appliance was able to increase the transverse dimension of the maxillary dental arch in the mixed dentition. The most appropriate timing for treatment appears to be before the eruption of the permanent lateral incisors.