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Fragile X syndrome is associated with an unstable CGG repeat sequence in the 5′ untranslated region of the first exon of the FMR1 gene. The present study involved the evaluation of factors implicated in CGG repeat stability in a normal sample from two Basque valleys (Markina and Arratia), to discover whether the Basque population shows allelic diversity and to identify factors involved, by using the data in conjunction with previous findings. The study was based on a sample of 204 and 58 X chromosomes from the Markina and Arratia valleys, respectively. The CGG repeat, the AGG interspersion and two flanking microsatellite markers, FRAXAC1 and DXS548, were examined. In the Markina valley, gray zone alleles (⩾35 CGG repeats) were associated with anchoring AGGs, with the longest 3′ pure CGG repeats of the valley (=15), with the 5′ instability structure 9+n and with one principal fragile X FRAXAC1–DXS548 haplotype 42–50. In the Arratia valley, gray zone alleles (⩾35 CGG repeats) showed the highest frequency among the Basque samples analyzed, and were associated with anchoring AGGs, with the longest 3′ pure repeats (⩾20), with the 5′ instability structure 9+ n and with one ‘normal’ FRAXAC1–DXS548 haplotype 38–40 (these data from Arratia suggest the existence of a ‘protective’ haplotype). The results showed, on the one hand, differences between Markina and Arratia in factors implicated in CGG repeat instability and, on the other hand, a great similarity between the general Basque sample from Biscay and the Markina valley.

Numerous studies have shown there is consistent evidence implicating genetic factors in the etiology of autism. In some cases chromosomal abnormalities have been identified. One type of these abnormalities is gaps and breaks nonrandomly located in chromosomes, denominated fragile sites (FS). We cytogenetically analyzed a group of autistic individuals and a normal population, and we examined the FS found in both samples with the aim of (1) comparing their FS expression, (2) ascertaining whether any FS could be associated with our autistic sample, and (3) examining if there are differences between individual and pooled-data analyses. Different statistical methods were used to analyse the FS of pooled and individual data. Our results show that there are statistically significant differences in the spontaneous expression of breakages between patients and controls, with a minimal sex difference. Using the method for pooled data, eight autosomal FS have preferential expression in patients and five patients were found to be positive at FS Xq27.3. With the method per-individual analysis, four FS emerged as specific in our autistic sample. Inferences of FS from pooled data were different from those of individual data. The findings suggest that although analysis of pooled data is necessitated by the problem of sparse data, analysis of single individuals is essential to know the significance of FS in autism.

Se ha llevado a cabo un estudio transversal con el objetivo de realizar un análisis topográfico del polo posterior maculopapilar de la retina, relacionando los cambios objetivados en el espesor de dicha región en un grupo de pacientes con enfermedad de Alzheimer (EA) leve, en comparación con un grupo control. Mediante la OCT, se han determinado los espesores medios de las áreas macular y hemipapilar temporal divididas en segmentos. El análisis de los datos obtenidos muestra un adelgazamiento significativo en algunos sectores maculares y peripapilares en pacientes con EA leve, elaborándose un mapa que revela los sectores de la mácula y la papila donde se concentran dichos cambios. Este hallazgo pone en el punto de mira a aquellas regiones maculopapilares que pudieran emplearse en el futuro como posible biomarcador para el diagnóstico precoz y seguimiento de la EA. Palabras clave: Enfermedad de Alzheimer (EA), Polo posterior maculopapilar, Tomografía de coherencia óptica (OCT), Biomarcador. The aim of this transversal study was to perform a topographic analysis of the macula and the temporal papillary region of the retina and to relate it with the changes seen in the macular and peripapillary retinal thickness in a group of patients with mild Alzheimer's disease (AD) compared with control. Macular and peripapillary thickness were measured by optical coherence tomography (OCT). It was found a significant macular and peripapillary thinning in some sectors in mild AD patients in comparison with control group, getting a map that revealed the earlier areas affected in AD. Therefore, this finding point to those regions in the macular and papillary region of the retina that could be useful as early biomarker for follow-up in AD. Key words: Alzheimer's Disease, Maculopapillary posterior pole, Optical Coherence Tomography, Biomarker.

The fragile X syndrome is an X-chromosome-linked dominant disorder with reduced penetrance. It is the most common inherited form of mental retardation. The molecular basis is usually the unstable expansion of a CGG trinucleotide repeat in the 5' untranslated region of the first exon of the FMR1 gene, which resides at chromosome position Xq27.3 and is coincident with the cytogenetic fragile site FRAXA, which characterizes the syndrome. In the Biscay province of the Basque Country the prevalence of FRAXA in a mentally retarded sample of non-Basque origin is in the range of other analyzed Spanish populations. In the sample of Basque origin we have not found FRAXA site expression and the repeat size is in the normal range. Based on this, we have examined FMR1 gene stability in normal individuals of Basque origin from the Biscay province. This study is based on a sample of 242 X chromosomes. The results from the CGG repeat region of FMR1 indicate that a prevalence of predisposing normal alleles toward repeat instability in the Basque population is 0.00% or near to it. This could be 1 of the explanations of the apparently low fragile X syndrome incidence found in the Basque mentally retarded sample analyzed by us. This low incidence does not seem to be associated with the flanking microsatellite markers.

We have analyzed the a-b ridge count and its fluctuating asymmetry in a sample (331 males and 290 females) from the Basque region of Alava province, Spain. Significant bimanual differences in the a-b ridge count are apparent only for females, and the sexual differences are significant for both hands. A comparison of the results in the Alava Basque population with results for other Basque populations showed sexual dimorphism. The results for fluctuating asymmetry do not support the hypothesis that if the regression of fluctuating asymmetry on the right and left hands is quadratic, the fluctuating asymmetry is a result of developmental homeostasis. Our data seem to indicate also that the factors that determine the a-b ridge count are canalized in females and males in the same way.

Palmar dermatoglyphics of a sample including 552 males and 701 females from 8 Basque valleys were analyzed. We studied the frequency of palmar pattern types and compared them using correspondence analysis. The results of this comparative study show that there is diversity among valleys and also that this diversity depends on the trait and on sex. Genetic drift could explain this variability found in the Basque population.

Finger ridge counts of a Spanish Basque sample (841 males and 911 females) were subjected to principal components analysis. This analysis was carried out by means of correlation matrices computed from 20 ridge counts, using both radial and ulnar counts for each finger. The interpretation of the components was performed, firstly from the unrotated factorial matrix, and then from the rotated factorial matrix. Rotation permitted a better resolution of the components. Our results also showed the contrast between the radial and ulnar sides of fingers and the existence of three digital components which represent the \"radiality,\" the \"ulnarity\" and the intermediate position.

Eighty-six females and 79 males from the Basque valley of Deba were analyzed with respect to their digital patterns using correspondence analysis. We found that there was a significant sexual difference for only one type of pattern, tented arch. Also, this population was compared with other Basque valley populations and with other Spanish populations. We found great variability among Basque subpopulations, despite their supposed common origin. Dermatoglyphic distances for some traits can be interpreted as genetic distances because there is high heritability of these traits. The results of the comparison between the Deba valley population and other Spanish populations showed that the Deba population is markedly distant from the other populations.

The possible inheritance of two asymmetries, hand clasping and arm folding, have been analyzed in 86 families with 414 progeny indigenous to Spanish Basque Country. The results show that the two analyzed traits are not sex linked. The analysis of family data shows evidence that one of the asymmetries, arm folding, is familial and probably genetic.