Showing papers on "Ring chromosome published in 1979"

Lack of Spontaneous Sister Chromatid Exchanges in Somatic Cells of DROSOPHILA MELANOGASTER-a Reply.

Abstract: Neural ganglia of wild type third-instar larvae of Drosophila melanogaster were incubated for 13 hours at various concentrations of BUdR (1, 3, 9, 27 µg/ml). Metaphases were collected with colchicine, stained with Hoechst 33258, and scored under a fluorescence microscope. Metaphases in which the sister chromatids were clearly differentiated were scored for the presence of sister-chromatid exchanges (SCEs). At the lowest concentration of BUdR (1 µg/ml), no SCEs were observed in either male or female neuroblasts. The SCEs were found at the higher concentrations of BUdR (3, 9 and 27 µg/ml) and with a greater frequency in females than in males. Therefore SCEs are not a spontaneous phenomenon in D. melanogaster, but are induced by BUdR incorporated in the DNA. A striking nonrandomness was found in the distribution of SCEs along the chromosomes. More than a third of the SCEs were clustered in the junctions between euchromatin and heterochromatin. The remaining SCEs were preferentially localized within the heterochromatic regions of the X chromosome and the autosomes and primarily on the entirely heterochromatic Y chromosome.—In order to find an alternative way of measuring the frequency of SCEs in Drosophila neuroblasts, the occurrence of double dicentric rings was studied in two stocks carrying monocentric ring-X chromosomes. One ring chromosome, C(1)TR 94–2, shows a rate of dicentric ring formation corresponding to the frequency of SCEs observed in the BUdR-labelled rod chromosomes. The other ring studied, R(1)2, exhibits a frequency of SCEs higher than that observed with both C(1)TR 94–2 and rod chromosomes.

Ring chromosome 6: case report and review of literature.

Abstract: A ring chromosome 6 has been identified by GTG-banding in a male with microcephaly, growth retardation, seizures, epicanthus, hypertelorism, micrognathia, and other congenital anomalies. Cytogenetic studies indicate the instability of the ring chromosome. The most common findings in subjects with ring 6 include: profound to moderate mental retardation, microcephaly, prenatal growth failure, retarded bone age, epicanthal folds, flat nasal bridge, short neck, ears low-set or malformed, microphthalmia, and micrognathia. Linkage studies, including HLA, are consistent with reported maps of chromosome 6.

Ring chromosome 15 syndrome.

Abstract: Two new cases of ring chromosome 15 are reported. A review of the nine cases described in the literature shows that ring chromosomes 15 are associated with a rather uniform phenotype characterized by slight to moderate mental retardation, marked pre- and postnatal growth failure, triangular face, and short hands and feet.

Ring chromosome 6 in a child with minimal abnormalities.

Abstract: We describe a boy with a ring chromosome 6 and short stature, mild micrognathia, and bilateral transitional/simian creases. Five other patients with a ring 6 have been reported. The clinical and cytogenetic observations of all six patients are compared and discussed.

Three cases of ring chromosome 2, one derived from a paternal 2/6 translocation.

Abstract: Two cases of primary ring chromosome 2 and one case of a ring secondary to a paternal 2/6 translocation are described and compared with a fourth case of ring 2 from the literature. The breakpoints in two cases are identical and the same as the breakpoint on chromosome 2 in the composite 2/6 ring. The three primary rings have a number of symptoms in common, but other cases are needed to identify a possible deletion syndrome. The levels of the enzyme MDH-1 were within the normal range in Cases 1 and 2. Thus we localised the locus for MDH-1 to segment 2p23→p25; this had previously been localised to segment p23→pter.

Ring chromosome 22 in a mentally retarded child and mosaic 45,XX,-15,-22,+t(15;22)(p11;q11)/ 46,XX,r(22)/46,XX karyotype in the mother

Abstract: A ring chromosome 22 is described in a 6-year-old mentally retarded boy, who presented a dysmorphic syndrome. The ring chromosome 22 was inherited from the mother, in whom a 46,XX/46,XX,r(22)/45,XY,-15,-22,+t(15;22)(p11;q11) mosaic karyotype was found, indicating a high degree of instability of the chromosome(s) 22 in this woman.

Ring chromosome 17 in a mentally retarded boy.

Abstract: A six-year-old boy was found to have a ring chromosome 17. In addition to psychomotor retardation, speech delay and seizure disorders, his abnormal phenotypic features included epicanthal folds, broad depressed nasal bridge, protruding thick upper and lower lips, micrognathia, narrow high arched palate, short fifth fingers with a mild degree of clinicodactyly, multiple cafe-aui-lait spots, and abnormal dermatoglyphics.

Ring chromosome 10 associated with multiple congenital malformations.

Abstract: A 46,XY,r(10) karyotype was found in lymphocytes and skin fibroblasts cultured from a 8-month-old male showing multiple malformations and severe mental retardation. A comparison of the clinical features observed in cases in which a 10 ring was identified by means of banding techniques has been also attempted.

Clonal evolution of marker chromosomes in a case of myelofibrosis with myeloid metaplasia and myeloblastic transformation.

Abstract: The diverse spectrum of acquired chromosome abnormalities in a female patient with myelofibrosis and myeloid metaplasia is described. A sequence of karyotypic evolution involving a ring chromosome is postulated. The terminal clinical picture was unusual in that there was obstructive renal failure from extramedullary myeloblastic transformation and infiltration of the bladder, and this was also present in other sites. Initially neutrophils showed low alkaline phosphatase activity but latterly two distinct populations in which cells had either high activity or none.

A Ring Chromosome 9 in an Infant with Malformations

Abstract: A low-birth-weight infant with malformed upper extremities and congenital heart disease was observed. Cytogenetic analysis revealed a 46,XY,r(9)(p24q34) complement.

A case of D13 ring chromosome.

Abstract: A case of D ring chromosome identified with trypsin banding as a 13 with loss of the bands p12 and q34 is reported. The clinical features characteristically associated with the loss of these specific segments were present.

Moderate mental retardation and nonspecific dysmorphic syndrome associated with ring chromosome 9.

Abstract: A ring chromosome 9 is reported in a 12-year-old, moderately mentally retarded boy. As in other ring chromosome 9 patients, the clinical stigmata are nonspecific and their expressivity is mild. The finding of two normal cells of a total of 121 cells examined favors the hypothesis of a postzygotic, mitotic origin of the ring chromosome formation.

The child with chromosome ring 15.

Abstract: A case of ring chromosome was reported. By application of different techniques it was identified as 15 r. The boy 19 months old was of a short stature, small skull and slight psychomotoric retardation.

[46,XX/46,XX,del (10) (p13)/47,XX,+r/47,XX,del (10) (p13), + r mosaicism and partial trisomy 10p phenotype (author's transl)].

Abstract: The mosaicism 46,XX/46,XX,del(10)(p13)/47,XX, +r/47,XX,del(10)(p13), +r was found in the lymphocytes and the fibroblasts of a patient with the following : profound mental retardation; craniofacial dysmorphism with frontal bossing, fine eyebrows, a large hypoplastic nasal bridge, prognathism of the upper jaw, thick lips; a long and thin neck; congenital heart disease; skeletal malformations, with club feet; and hypotonia and lax ligaments. These malformations, compatible with the trisomy 10p syndrome, suggest that the supernumerary ring chromosome was composed of 10p material. An increase of HK1 and GOT1 activities was found. This is in favour of a partial trisomy of chromosome 10. The relative frequencies of the clones constituting the mosaic vary from tissue to tissue and with time.

Some clinical and cytogenetic observations on a ring chromosome 13 (p11 q34).

Abstract: A girl of 9-10/12 years of age with 46,XX,r(13)(p11q34) karyotypes was studied. She presented some clinical and radiological features, such as pectus excavatum, scalp alopecic area, 12th rib agenesis, hypoplastic pelvis, small gluteal pits and hypoplasia of the external genitalia in a female, which have never been previously described in other cases with ring 13 chromosomes. Cytogenetically, in vivo and in vitro viability of complete monosomic and partially trisomic and tetrasomic cells was found. The presence of nucleolus organizer regions and association of the ring 13 with other acrocentrics question the exclusivity of these attributes to acrocentrics p12.

A Female with Ring chromosome 18

Abstract: Chromosome studies were done on a 3-yearold Japanese female infant with mental and developmental retardation, susceptibility to infection and multiple anomalies. Her parents and elder brother were normal. She was delivered at 38-week gestation without a notable comlication, with the weight of 2,400 g and the height of 45 cm. At 46 days after birth, she was admitted to our hospital due to cyanotic spells during sucking and crying, and failure to thrive. At that time she was found to have a V.S.D. and P.S. by EKG and chest X-rays. She had also had recurrent infections of respiratory, urinary and gastrointestinal tracts during the first 2 years of life, but since then she had no further involvement. Development was consistently delayed, i.e., fixation of neck at 12 months and walking without support at 7 years of age. The weight and the height at 3 years of age were 7,610g and 78 cm, respectively. Physical examination showed a round face with ocular hypertelorism, strabismus, epicanthal folds, protruded and moderately low set ears, carp mouth, high arched palate, irregularity of dental arch with many carieses and coarse brown-black hairs. Scoliosis, mild everted knees, clubfoot of both sides, high position of both 2nd toes and spindle shaped fingers were also noted. Laboratory examinations including EEG, serum immunoglobulin, phytohemagglutinin blastformation test and endocrinological studies were all normal. Dermatoglyphic examinations were as follows: all the digits carried a whorl except for the thumb and the 5th finger of the right hand which had ulnar loop, the atd angle of palm: 37' (r) and 50' (l), hypothenar pattern of palm: loop (r. and 1). Chromosome examinations were done on peripheral lymphocytes. The results showed: ninety percent of cells of 46 chromosomes with one ring chromosome, 5% of 45 without ring, 4% of 47 with two rings and remaining few a large ring. The break point of the chromosome was further analysed by Giemsa-trypsinbanding method and finally the karyotype was determined as 46, XX, r (18) (pll+q23) according to Paris conference. The parents and the brother showed normal karyotypes. Twenty six kinds of the genetic markers of the patient and her parents were also examined. But the localization of genetic locus was not found on the deleted chromosome. Various ring chromosomes, the susceptibility to infection and dwarfism observed in the present case were discussed.