Partial trisomy 22q with elevated arylsulfatase-A activity.

A two years-old, severely mentally retarded male is reported with 22q trisomy. After the recent confirmation of the localisation of arylsulfatase-A (ARSA) on chromosome 22, the elevated activity of this enzyme (about 1,5 times the normal values) in the present patient may be another example of a gene dosage effect in autosomal imbalance.     

Acrocentric/18p translocation in two mentally retarded males. Delineation of the adult phenotype

In this report we describe two adult male patients with a chromosomal rearrangement involving the short arm of chromosome 18 and an acrocentric chromosome. In addition to moderate mental retardation and verbal disability they presented dysmorphic stigmata similar to those found in the Noonan syndrome.     

TNF-induced necroptosis in L929 cells is tightly regulated by multiple TNFR1 complex I and II members

TNF receptor 1 signaling induces NF-κB activation and necroptosis in L929 cells. We previously reported that cellular inhibitor of apoptosis protein-mediated receptor-interacting protein 1 (RIP1) ubiquitination acts as a cytoprotective mechanism, whereas knockdown of cylindromatosis, a RIP1-deubiquitinating enzyme, protects against tumor necrosis factor (TNF)-induced necroptosis. We report here that RIP1 is a crucial mediator of canonical NF-κB activation in L929 cells, therefore questioning the relative cytoprotective contribution of RIP1 ubiquitination versus canonical NF-κB activation. We found that attenuated NF-κB activation has no impact on TNF-induced necroptosis. However, we identified A20 and linear ubiquitin chain assembly complex as negative regulators of necroptosis. Unexpectedly, and in contrast to RIP3, we also found that knockdown of RIP1 did not block TNF cytotoxicity. Cell death typing revealed that RIP1-depleted cells switch from necroptotic to apoptotic death, indicating that RIP1 can also suppress apoptosis in L929 cells. Inversely, we observed that Fas-associated protein via a death domain, cellular FLICE inhibitory protein and caspase-8, which are all involved in the initiation of apoptosis, counteract necroptosis induction. Finally, we also report RIP1-independent but RIP3-mediated necroptosis in the context of TNF signaling in particular conditions.     

Down's syndrome in brother and sister without evident trisomy 21

Summary In the present report two siblings with the typical Down's phenotype but without evident full or partial 21 trisomy are described. The finding of a regular 21 trisomy in a minority of the cells in the elder patient favors the hypothesis that both present a hardly demonstrable normal/trisomy 21 mosaicism and may be examples of a constitutional familial tendency to nondisjunction in man.     

On the excess of mental retardation and/or congenital malformations in apparently balanced reciprocal translocations. A critical review of the Leuven data 1966-1991.

In this report we review 286 reciprocal translocations (rcpt) diagnosed in Leuven in the period 1966, mid 1991. They were selected from a total number of 82,000 patients karyotyped for constitutional reasons. Special attention is paid to: (1) the phenotypic effect of de novo reciprocal chromosomal rearrangements and (2) the incidence of mental retardation/congenital malformations (MR/CM) in familial rcpt. Important conclusions of this study were: 1) The high incidence of MR/CM in de novo rcpt, not only in patients with complex chromosomal rearrangements (greater than 80%) but also in patients with classical two breaks rcpt (greater than 60%). In contrast, the phenotypic effect of normal/mosaic rcpt seems to be minimal. 2) The overall incidence of MR/CM in carriers of familial balanced rcpt was 6.4%. Interestingly, the incidence of MR/CM problems in rcpt carriers from families detected because of reproductive failure was not increased (2.3%). However, the risk to find MR/CM in a rcpt carrier was much higher (12.8%) if he/she belonged to a family in which the rcpt was detected in an index patient with MR/CM.     

Interstitial delection of the long arm of chromosome 8

Summary This report describes a polymalformed 18-month-old male with an interstitial deletion of the long arm of chromosome 8. His karyotype is: 46,XY,del(8)(q21).     

Groupe d'etude Des Rythmes Biologiques (Societe Francophone De Chronobiologie)

The Groupe d'Etude des Rythmes Biologiques (GERB) held its annual meeting in Paris (25-26 January, 1990). Keeping with the objectives defined when it was founded, the Group proposed a small number of lectures, each devoted to a particular field of rhythmicity, and opened its tribune to free communications provided that they had been accepted by the referees.     

Differences in agglutinability of adult and fetal human fibroblasts using phytohemagglutinin

Whereas Concanavalin A (Con A) and Wheat Germ Agglutinin (WGA) detect differences in the agglutinability of transformed, established and secondary cultures, Phytohemagglutinin (PHA) detects differences between cultured adult and fetal human fibroblasts. Adult cells agglutinate with PHA to the same extent as transformed cells, whereas fetal cells show significant agglutination only after trypsinization. Differences in cell size, growth rate, surface architecture or binding of fluorescent PHA could not be demonstrated between adult and fetal cells. Although the basis for this apparent difference in agglutinability remains unknown, it is the first demonstration that fetal cells (even after prolonged in vitro culture) retain at least some surface properties not shared by adult or transformed cells.