Ataxia-telangiectasia (A-T) is an autosomal recessive disorder involving cerebellar degeneration, immunodeficiency, chromosomal instability, radiosensitivity and cancer predisposition. The responsible gene, ATM, was recently identified by positional cloning and found to encode a putative 350 kDa protein with a Pl 3-kinase-like domain, presumably involved in mediating cell cycle arrest in response to radiation-induced DNA damage. The nature and location of A-T mutations should provide insight into the function of the ATM protein and the molecular basis of this pleiotropic disease. Of 44 A-T mutations identified by us to date, 39 (89%) are expected to inactivate the ATM protein by truncating it, by abolishing correct initiation or termination of translation, or by deleting large segments. Additional mutations are four smaller in-frame deletions and insertions, and one substitution of a highly conserved amino acid at the Pl 3-kinase domain. The emerging profile of mutations causing A-T is thus dominated by those expected to completely inactivate the ATM protein. ATM mutations with milder effects may result in phenotypes related, but not identical, to A-T.
We report on a case of absent pulmonary valve syndrome in a woman with a history of one healthy child and one child with tetralogy of Fallot with absent pulmonary valve. The diagnosis was missed at the first ultrasound examination performed at 13 + 5 weeks of gestation and correctly diagnosed at 21 + 5 weeks. Re-evaluation of the ultrasound examination recorded at 13 + 5 weeks exhibited severe insufficiency of the pulmonary valve at this time. However, neither dilatation of the right and left pulmonary arteries nor asymmetry of the ventricles were present at that time. The pregnancy was terminated at 22 + 1 weeks of gestation when autopsy confirmed the diagnosis of absent pulmonary valve syndrome. Karyotyping of the fetus after termination of pregnancy revealed normal chromosomes. Echocardiography of the parents and the healthy sibling revealed normal results.
Abstract. A molecular cytogenetic study was performed on 48 infertile patients who were identified as carriers of balanced translocations (40 cases), inversions (6 cases) or insertions (2 cases) by means of banding cytogenetics. Cases with a Robertsonian translocation or pericentric inversion 2 or 9 were not included. In summary, 100 break-events occurred in these patients, and 90 different chromosomal regions were involved. Thus, this study confirmed the presence of abnormal karyotypes in a subgroup of patients seeking infertility treatment. Breaks were demonstrated to appear preferentially in GTG-light bands in these patients. Furthermore, the observed breakpoints were associated with genomic regions prone to instability due to the presence of segmental duplications. Nonetheless, further detailed molecular analysis will be necessary in the future to characterize the mechanisms and genetic basis for this phenomenon.
Larsen syndrome shows a broad spectrum of clinical manifestation ranging from a lethal form of the disorder to a mild clinical expression with absence of major diagnostic features. Here we show that even intrafamilial manifestation may vary extremely to the point that Larsen syndrome in a father has been diagnosed only by typical sonographic features in an affected fetus.
Increasing numbers of women≥35 years of age rely on the individually adjusted risk figure to make a decision about invasive testing. The application of these selective procedures can reduce the rates of invasive testing with fewer losses of normal fetuses and led to an earlier diagnosis of aneuploidies.
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