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(fig 2A, B). Radiographs showed craniofacial disproportion and severe dysostosis. The ilia were hypoplastic with a trident configuration of the acetabula, the metaphyseal end plates of the long bones, mainly the femora and tibiae, were irregular, and the diaphyses were thin (fig

The Wiedemann-Rautenstrauch syndrome (WRS) (OMIM 264090) is a rare progeroid entity. WRS patients are characterized by premature aging present at birth including pseudohydrocephalus, cranio-facial disproportion, reduced subcutaneous fat, thin skin, rigid and thick joints, and neonatal teeth in some cases. Here we describe three sibs with WRS from unaffected parents and without consanguinity. Our findings support autosomal recessive inheritance in WRS and support the possibility of homozygocity mapping as a good approach to find the causative gene.

Ten affected males studied from four generations of a Colombian family with Dyggve‐Melchior‐Clausen (DMC) syndrome are described. The ages of the affected males varied from 13 to 50 years and they presented with typical clinical and radiological manifestations of the syndrome. The association of normal intelligence and a clear X‐linked recessive inheritance in this family is evidence of heterogeneity in the Dyggve‐Melchior‐Clausen syndrome. In agreement with previous reports for DMC dwarfism, this new form has normal mucopolysaccharide excretion.

Cytogenetic studies on lymphocytes from a girl aged 3 years and 10 months revealed revealed a ring chromosome 15. Several banding methods showed the r(15) chromosome not to have any apparent deletion of the long arm. The silver staining technique for nucleolar organizer regions showed an NOR positive region (band p12). In only a few cells was a chromosome 15 missing. The size of the r(15) was found to be constant. Comparison with 11 previous reported cases in the literature shows that the clinical manifestations in the different patients with ring chromosome 15 are constant although not clinically identifiable and it appears likely to attribute them to a significantly retarded intrauterine and postnatal growth instead of presumed deficiency in the long arm and mosaic configurations.

A new case of partial trisomy 3q is reported in a 5-year-old female with severe congenital malformations and psychomotor retardation. A review of the literature, with a total of 11 patients, allows us to conclude that the clinical picture reminiscent of the Cornelia de Lange syndrome is caused by the trisomic state.

Introduction. Free trisomy 21 is responsible for 95% of Down syndrome cases. Advanced maternal age and susceptible recombination patterns are recognized risk factors associated to Down syndrome. Maternal origin of trisomy occurs in approximately 90% of cases; paternal and mitotic origin share the remaining 10%. However, the recombination events that serve as a risk factors for trisomy 21 have not been carefully characterized. Objective. To analyze and validate observations in a sample of Colombian trysonomy 21 cases. Materials and methods. Twenty-two Colombian families were selected, each with one affected Down syndrome (free trisomy 21) child. Microsatellite polymorphisms were used as DNA markers to determine the parental/stage origin of non-disjunction and recombination events. Nonparametric tests were used to compare our results with those reported. Multiple correspondence analysis was used to outline different groups and their associations. Results. Distribution of trisomy 21 was 90.9% maternal, 4.5% paternal and 4.5% from mitotic origin, similar to distributions reported previously. However, we found differences in the frequency of maternal meiotic stage errors between the present study (46.1% meiosis I and 53.9% meiosis II) compared to those reported previously (70% meiosis I and 30% meiosis II). Multiple correspondence analyses showed association of either local recombination events or absence of recombination with specific non-disjunction stages. Conclusions. Recombination patterns found in this study support the hypothesis that susceptible chiasmate configurations are associated to maternal meiosis I and meiosis II errors. Nondisjunction frequencies between maternal meiotic stages need to be clarified in our population.Key words: Down syndrome; nondisjunction, genetic; trisomy; meiosis; recombination, genetic; microsatellite repeats.Origen parental, estado de no disyunción y recombinación meiótica del cromosoma 21 extra en el síndrome de Down: estudio en una muestra de población colombiana Introducción. La trisomía 21 libre es responsable del 95% de los casos de síndrome de Down. La edad materna y la recombinación son los principales factores de riesgo asociados con la concepción de estos individuos. El origen materno de la trisomía ocurre en el 90% de los casos, mientras que los casos de origen paterno y mitótico comparten un 10%. Por otra parte, la recombinación como factor de riesgo para la trisomía 21 no ha sido comprobada completamente. Objetivo. Analizar y validar estas observaciones en una muestra colombiana de casos con trisomía 21 libre. Materiales y métodos. Se estudiaron 22 afectados con síndrome de Down (trisomía libre) y sus respectivos padres. Se usaron marcadores microsatélites de ADN para determinar el origen en los progenitores, el estado de no disyunción y los eventos de recombinación. Por COMUNICACIÓN BREVE 142 Biomédica 2007;27:141-8 Ramírez NJ, Belalcazar HM, Yunis JJ et al medio de pruebas no paramétricas se compararon los resultados con los reportados en la literatura. Se re...

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