Dicentric i(Yq) chromosome and azoospermia

We have studied a 43-year-old man with azoospermia. Chromosome analysis, using G-, Q-, and C-banding techniques, showed a dicentric 46,X,i(Yq) chromosome abnormality. The clinical, cytogenetic, endocrine, and testicular histologic findings are presented. The case is discussed in relation to the pertinent literature. This represents the first phenotypic male with this karyotype ever reported.     

Non-random chromosome segregation and chromosome eliminations in the fly Bradysia (Sciara)

Chromosome Research - Mendelian inheritance is based upon random segregation of homologous chromosomes during meiosis and perfect duplication and division of chromosomes in mitosis so that the...     

A new chromosome preparation technique for Coleoptera (Insecta)

A new squash technique with Giemsa staining is described for use with Coleoptera and Tettigonidae (Orthoptera). This method yields chromosome preparations suitable for the application of banding techniques.     

Unstable dicentric iso(Yq) chromosome in a pseudohermaphrodite

An infant with ambiguous genitalia, uterus, tubes, and bilaterally undescended testes was found to have an unstable dicentric Yq chromosome, and 45,X/46,X,dic i(Yq)/47,X,i(Yq) i(Yq) mosaicism in lymphocytes and fibroblasts. A few other minor cell lines were found in peripheral blood lymphocytes. These findings indicate a high degree of mitotic instability in the centromere of the dicentric i(Yq) chromosome in this patient.     

Mapping of human non-muscle type cofilin (CFL1) to chromosome 11q13 and muscle-type cofilin (CFL2) to chromosome 14

Cofilin is a widely-distributed, intracellular, actin binding protein which is involved in the translocation of actin-cofilin complex from cytoplasm to nucleus. We have cloned a non-muscle-type cofilin (CFL1) from a human promyelocytic cDNA library and mapped this to human chromosome 11 by PCR amplification of 3' untranslated sequence in a panel of rodent-human somatic cell hybrids, and to the interval 11q12-q13.2 in a chromosome 11 somatic cell hybrid mapping panel. Confirmation of regional localisation to 11q13 has been obtained by fluorescent in situ hybridisation of genomic cosmid clones, by demonstration of the presence of both SEA (the human homologue of avian retrovirus pro viral tyrosine kinase, 11q13) and CFL1 in some of these clones and by close linkage of CFL1 to SEA in a panel of high-dose irradiation hybrids.
We have identified human muscle-type cofilin sequences by comparison of human expressed sequence tags with M-type cofilins of other species and we have mapped the human M-type cofilin, CFL2, to chromosome 14.     

The human Hox-bearing chromosome regions did arise by block or chromosome (or even genome) duplications

Many chromosome regions in the human genome exist in four similar copies, suggesting that the entire genome was duplicated twice in early vertebrate evolution, a concept called the 2R hypothesis. Forty-two gene families on the four Hox-bearing chromosomes were recently analyzed by others, and 32 of these were reported to have evolutionary histories incompatible with duplications concomitant with the Hox clusters, thereby contradicting the 2R hypothesis. However, we show here that nine of the families have probably been translocated to the Hox-bearing chromosomes more recently, and that three of these belong to other chromosome quartets where they actually support the 2R hypothesis. We consider 13 families too complex to shed light on the chromosome duplication hypothesis. Among the remaining 20 families, 14 display phylogenies that support or are at least consistent with the Hox-cluster duplications. Only six families seem to have other phylogenies, but these trees are highly uncertain due to shortage of sequence information. We conclude that all relevant and analyzable families support or are consistent with block/chromosome duplications and that none clearly contradicts the 2R hypothesis.     

Duplication (17p) in a child with an isodicentric (17p) chromosome

We present a child with multiple structural defects due to duplication of the short arm and a small portion of the long arm of chromosome 17. Three children with similar cytogenetic abnormalities have been reported previously. The karyotype contained an isodicentric chromosome derived from chromosome 17. A clue to the mechanism that produced the isochromosome was retained in the genome in the form of a part of the chromosome 17 long arm which was attached to the short arm of a chromosome 10.     

The sex-determining region of theMegaselia scalaris (Diptera) Y chromosome

InMegaselia scalaris (Loew) the presence or absence of a male-determining factor, M, is responsible for sex determination. In two wild-type strains, M is located on the homomorphic chromosome pair 2. In the laboratory line Except42 a new Y chromosome was created by recombination between the original Y and the original X chromosome. The Except42 Y chromosome has conserved the sex-determining function and four molecular markers of the original Y chromosome, while 13 original Y markers have been lost. The new Y chromosome, therefore, consists of roughly one-quarter of the original Y chromosome and three-quarters of the original X chromosome. To define the sex-determining region, cosmid clones, one from the original X and one from the original Y chromosome region of the Except42 Y chromosome, were isolated and used as probes for chromosomalin situ suppression (CISS) hybridization. The CISS hybridization signals map the conserved Y segment, including the male-determining factor, to the distal segment of the short arm of the Y chromosome.     

Supernumerary chromosome marker (1) in a developmentally delayed child

A 15-month-old boy with mild developmental delay and several minor anomalies was found to be mosaic 46, XY/47, XY, +mar(l). The marker r(l) was a small de novo ring identified by FISH with a painting type DNA probe. © 1995 Wiley-Liss, Inc.     

Isochromosome (17q) in Philadelphia chromosome (Ph1)-negative juvenile chronic myelocytic leukemia

A dicentric isochromosome of the long arm of one chromosome #17 was the only abnormality present in a 12-year-old boy with Philadelphia chromosome (Ph¹)-negative juvenile chronic myelocytic leukemia. This association does not seem to have been reported in the literature. It is postulated that the finding of an isochromosome (17q) may also have a negative prognostic value in the Ph¹-negative type of chronic myelogenous leukemia.     

Characterization of chromosome structures of Falconinae (Falconidae, Falconiformes, Aves) by chromosome painting and delineation of chromosome rearrangements during their differentiation

Karyotypes of most bird species are characterized by around 2n = 80 chromosomes, comprising 7–10 pairs of large- and medium-sized macrochromosomes including sex chromosomes and numerous morphologically indistinguishable microchromosomes. The Falconinae of the Falconiformes has a different karyotype from the typical avian karyotype in low chromosome numbers, little size difference between macrochromosomes and a smaller number of microchromosomes. To characterize chromosome structures of Falconinae and to delineate the chromosome rearrangements that occurred in this subfamily, we conducted comparative chromosome painting with chicken chromosomes 1–9 and Z probes and microchromosome-specific probes, and chromosome mapping of the 18S–28S rRNA genes and telomeric (TTAGGG) _n sequences for common kestrel (Falco tinnunculus) (2n = 52), peregrine falcon (Falco peregrinus) (2n = 50) and merlin (Falco columbarius) (2n = 40). F. tinnunculus had the highest number of chromosomes and was considered to retain the ancestral karyotype of Falconinae; one and six centric fusions might have occurred in macrochromosomes of F. peregrinus and F. columbarius, respectively. Tandem fusions of microchromosomes to macrochromosomes and between microchromosomes were also frequently observed, and chromosomal locations of the rRNA genes ranged from two to seven pairs of chromosomes. These karyotypic features of Falconinae were relatively different from those of Accipitridae, indicating that the drastic chromosome rearrangements occurred independently in the lineages of Accipitridae and Falconinae.     

Interstitial deletion of chromosome 2 (p23p25)

We report a patient with a de novo interstitial deletion of the short arm of chromosome 2 (p23p25). The patient had microcephaly with prominent forehead and occiput, narrow rectangular face, clinodactyly, failure to thrive, delayed psychomotor development, and seizures. Maternal serum alpha-fetoprotein was undetectable at 18 weeks of gestation. Heterozygosity at the red cell acid phosphatase locus (SRO-2p25) and normal levels of red cell malate dehydrogenase (SRO-2p23) are findings consistent with the presence of genetic material from bands 2p25 and 2p23.     

A ring chromosome (No. 18) in a cyclops

A female infant manifesting multiple congenital anomalies including cyclopian deformity is described. Chromosomal analysis revealed a ring chromosome in place of one of the normal No. 18 homologs. Identification of this structurally abnormal chromosome was confirmed by fluorescence and "giemsa banding" techniques.     

Philadelphia chromosome (Ph) positive chronic myelocytic leukemia (CML): frequency of additional findings

This article documents the cytogenetic findings in 79 patients with typical Ph-positive chronic myelocytic leukemia (CML). Direct preparations of bone marrow and/or peripheral blood of 46 males and 33 females were studied with different banding techniques. Seventy patients were studied during chronic phase. Three (4.3%) had unusual or complex translocations: t(6;22)(p21;q11), t(8;12;9;22)(p21;q21;q34;q11), and t(9;11;22)(q34;q13;q11). One (1.4%) had a +Ph, 1 (1.4%) had a +8, 1 (1.4%) had a del(3)(p13,p23), and 4 of 30 males (13.3%) showed loss of Y chromosome. Five of 8 cases studied during blast crisis had additional abnormalities. The +8 occurred in 4 cases, +10 and +19 each in 3 cases, +6, + 9q+, and +13 each in 2 cases, and +5, +11, +14, +21, +Ph, i(17q), dic(1;9), and structural abnormalities of chromosomes #1, #5, #12, and #13 each in 1 case. Two cases studied in blast crisis alone had complex translocations leading to the Ph. Because it cannot be ruled out that these translocations are secondary, they were not included in the calculation of the frequency of atypical translocations.     

Partial deletion of long arm of chromosome 11: del (11) (q23)

The cytogenetic analysis of an infant with multiple congenital anomalies revealed a small deletion of the long arm of one No. 11 chromosome: 46,XX,del(11)(q23). The main clinical manifestations included: ocular colobomata, absent philtrum, severe congenital heart disease, contractures of the large joints and skin pigmentation. Both parents showed a normal chromosome constitution. In comparison to the previously reported cases of 11q-, the patient presented here had more severe congenital anomalies. The correlation of the size of the deletion, and the location of the break, with the physical findings is discussed.