Showing papers on "Ring chromosome published in 1975"

Ring chromosome 13 in a polymalformed anencephalic.

Abstract: In the 33rd week of pregnancy an amniocentesis was performed because of low estriol. X-ray indicated the presence of anencephaly and a premature delivery was induced. Necropsy, in addition to anencephaly, showed a wide variety of malformations. The fetal karyotype determined from cultured amniotic fluid cells revealed a ring chromosome 13.

Irregular phenotypic expression of ring chromosomes.

Abstract: 2 patients with 13- and C9-rings are reported. On reviewing the phenotypical features of the published ring carriers and comparing them with our results we do not find any characteristic similarities. This can be explained by cytogenetical and biological findings. We are therefore inclined to reject the existence of clear-cut ring chromosome syndromes.

Derivative chromosomal structures from a ring chromosome 4

Abstract: Summary. This report describes the results from cultured lymphocytes studied at metaphase, anaphase, and interphase from an individual with a ring chromosome 4. A ring was present in 90.1°/o of metaphases. Special attention was directed towards the occurrence of derivative chromosomal structures, such as partially duplicated and triplicated rings, tricentric rings, chains of 3 interlocked rings, rod-shaped chromosomes, "pulverized" rings, and others. The clinical features of the individual (small stature and impaired mental development, hypoplastic thmnbs, ptosis palpebrae hypoplastic external male genitalia, abnormal dermatoglyphic pattern) did not conform to a specific phenotype. Zusammen/assung. ]Die Lymphocyten eines Patienten mit Ringchromosom 4 wurden in der Meta-, Ana- und Interphase beobachtet. 90,1~o der Metaphasen wiesen einen Ring auf. Besondere Aufmerksarnkeit wurde abnormen, aus dem Ring entstandenen Chromosomen zugewandt. Es fanden sich u. a. : partielle Doppel- und Dreifachringe, Ringe mit 3 Zentromeren, Ringe aus 3 miteinander verketteten Ringen, stabfSrmige Chromosomen und ,,pulverisierte" Ringe. Die Symptome des t?atienten (Minderwuehs, Schwachsinn, Hypoplasie der Daumen, Ptosis palpebrae, Hypoplasie des gugeren Genitale, abnorme Dermatoglyphen) waren zum gr6Bten Tell unspezifisch.

Ring chromosome 15:r(15). Identification by R banding.

Abstract: Upon investigating the mental retardment of a small girl who was not dysmorphic, a ring chromosome D was discovered. Thermic moderate denaturation enabled us to confirm it as being an r(15). The r(15) syndrome scarcely affects the phenotype. On the other hand, height is consistently reduced.

Exclusion gene mapping utilizing patients with chromosome imbalance: the HL-A system as a prototype.

Abstract: 17 chromosomally unbalanced patients, their siblings and parents were tested for HL-A types and for up to 25 other polymorphic systems to determine whether there was gain or loss of an allele concurrent with the gain or loss of chromosome material. 5 patients had trisomy of part or all of a chromosome; 2 had trisomy of a segment and also deletion of chromosome material. All 7 were due to a familial translocation. The remaining patients had small deletions; 5 had ring chromosomes, 4 had rod deletions and 1 had missing chromosome material due to a heritable translocation. All cases were informative at the HL-A loci because of the high degree of polymorphism of the system whereas only some of the other systems were informative. None of the 17 patients showed unusual inheritance of HL-A or any other of the polymorphic systems examined. These results provide evidence excluding the HL-A and other loci from a number of possible locations in the human genome.

Ring 17 chromosome detected by amniocentesis.

Abstract: A fetus with a 46,XX,r(17) karyotype identified initially by amniocentesis and confirmed by banding studies is described. No significant phenotypic abnormalities were identified despite isolation of the ring chromosome from multiple fetal tissues. This paucity of abnormal features of gross development is consistent with findings in 3 previously reported patients with ring 17 chromosomes.

Ring chromosomes and leukaemia

Abstract: The observation of 2 leukaemic patients with ring chromosomes, and their comparison with a few previously reported cases, suggests a close association between this rare chromosomal abnormality and erythroleukaemia and indicate a poor prognostic significance of this finding.

Clinical and cytogenetic aspects of the 21 deletion syndrome.

Abstract: The clinical, cytogenetic and dermatoglyphic findings in a patient with a ring chromosome 21 are presented. This anomaly acts as a deletion of chromosomal material and results in specific congenital defects. A comparison is made with 24 cases of deletions involving chromosome 21 described in the literature. Six of these have been studied by means of recently developed chromosome banding techniques. Cases presumably arise through somatic non-disjunction or chromosome breakage. When the chromosomes of both parents are normal the recurrence risk is negligible.

[A dysplasia-epilepsy syndrome in a patient with ring chromosome 21].

Abstract: We report a 10 year old girl with psychomotor retardation, myoclonic syndrome and extreme photosensitivity. Clinical symptomatology and EEG-findings were not compatible with any of the known myoclonic syndromes. The patient's remarkable phenotype with short stature, dystrophy, facial dysmorphia characterized by antimongoloid palpebral fissures, broad root of the nose, coarse nose, inner epicanthic folds, dysplasia of the external ears, higharched palate, syndactylism between 2nd and 3rd toes on both sides, small narrow hands is suggested of a chromosomal disorder. A ring-shaped chromosome of the G-group (21--22) could be found. After using the Giemsa- and C-banding technique this chromosome could be identified as number 21. Patients with ring chromosome 21 or 22 are phenotypically not distinguishable. This is due to duplication-deficiency-variability of ring chromosomes in growing somatic tissues. The cellular genotype of ring chromosomes varies between monosomy, trisomy and polysomie.

Human acrocentric ring chromosomes and satellite association.

Abstract: In four cases of human acrocentric ring chromosomes r(21)(p13q22); r(21)(p11q22); r(13)(p11q?); and R(21)(P11Q22), association of the annular with normal D and G chromosomes was found This finding indicates that: 1) the "satellite" association is not terminal 2) the heterochromatic region (band p11) adjacent to the acrocentric short arm constriction contains nucleolar organizers (NOs), although bands p12 and 13 could not be excluded; and 3) band p11 probably has two different functional sites, a distal NO+ and a proximal NO- Related studies on three C/G translocation carriers suggest a non-specific interphase interchromosomal relationship