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J A Crolla

Publications and source records attributed to J A Crolla.

At least 55 records · Page 3Linked to original sources
PubMed1995

A search for uniparental disomy in carriers of supernumerary marker chromosomes.

As there is some evidence that individuals bearing supernumerary marker chromosomes (SMCs) might have an increased risk of being uniparentally disomic for the structurally normal homologues of the SMC, we made a systematic search for uniparental disomy of the autosomal homologues from which SMCs were derived. Of the 22 families studied, a biparental origin of the normal homologues was demonstrated in 21, and 1 case of paternal isodisomy of chromosome 6 was detected in the carrier of a supernumerary marker ring chromosome 6 which itself was of maternal origin. Our results confirm that uniparental disomy may be found in association with SMCs, but until more cases are studied we can only speculate on their frequency and the mechanism(s) which result in this phenomenon.

Chromosome Aberrations↗
PubMed1995

Telomeric translocations are uncommon.

Telomeric translocations are uncommon: Fluorescence in situ hybridisation with TTAGGG repeats as the probe was used to search for derivative chromosomes with telomeric repeats at the break-point junction in a sample of 16 translocations with at least one terminal breakpoint and ascertained through an aneuploid patient. There were 11 cases (8 autosomal and 3 X;Y translocations) with a de novo/unknown origin in the study group and 5 control familial rearrangements. At least 20 metaphases showing a clear telomeric signal on the relevant chromosomes(s) were analysed in each individual. All 16 translocations appeared to be reciprocal events as interstitial telomeric sequences were not found. The lack of telomeric translocations in this sample may be related, among other factors, to the relative absence of tertiary monosomies which are the most suitable candidates. These data and previously published information indicate that telomeric translocations are uncommon and differ from reciprocal exchanges in several relevant ways such as an exclusive unbalanced occurrence; a consistent de novo origin and therefore a non-significant recurrence risk; restricted malsegregations, namely 3:1 tertiary monosomy and adjacent-1; a yield of "pure" imbalances, and a proneness to exhibit a jumping behaviour.

Chromosome Aberrations↗
PubMed1994

Mixed gonadal dysgenesis and cell line differentiation. Case presentation and literature review.

A male patient with mixed gonadal dysgenesis, involving a streak gonad on the right and a histologically normal testis in the left, was found to have a 45,X/46,X,dic(Yp) chromosome constitution on peripheral blood cultures. Fibroblasts grown from both gonads showed the "normal" testicular tissue to have e 45,X/46,X,dic(Yp), whereas the cells from the streak gonad were all 45,X. The structure of the dic(Yp) chromosome was confirmed using non-isotopic in situ hybridization with Y centromere and Yp specific probes. On hormonal stimulation, testosterone levels rose by 50%. The "normal" testis was left in situ, but close follow up will be required in view of the malignant potential.

Cell Differentiation↗
PubMed1993

Mosaic tetrasomy 8p: molecular cytogenetic confirmation and measurement of glutathione reductase and tissue plasminogen activator levels.

We report the case of a 5-year-old girl with severe developmental disabilities, skeletal anomalies, hypotonia, rectal atresia, malrotation of the intestine, horseshoe kidney, vesicoureteric reflux, and minor facial anomalies. Conventional cytogenetic techniques suggested that she had a mosaic 46,XX/47,XX,+i(8p) constitution, and the identity of the isochromosome was confirmed by in situ hybridization and chromosome painting. Polymorphic DNA markers are consistent with the i(8p) having arisen as the result of a segregation error and centromere misdivision at the second maternal meiotic division. The i(8p) was seen in 17/25 (68%) lymphocytes at the age of one month but had declined to 31/100 (31%) cells by the age of 5 years. At this time the i(8p) was seen in 30/68 (44%) cultured skin fibroblasts. The proposita had an approximately twofold increase in red cell glutathione reductase activity but a normal level of tissue-plasminogen activator. These enzyme results are consistent with the known localisation of the glutathione reductase gene on the short arm of chromosome 8 but suggest that the tissue-plasminogen activator gene may map outside this region.

Abnormalities, Multiple↗
PubMed1993

Molecular cytogenetic characterization of three familial cases of satellited Y chromosomes.

Three families in which a satellited Y chromosome (Yqs) was segregating without apparent phenotypic effect were re-investigated with non-isotopic in situ hybridization methods. Active nucleolus organizer regions were seen in the distal long arm region of all Yqs chromosomes studied and in situ hybridization with the probe D15Z1 showed that, in all three families, the Yqs was the result of a 15p;Yq translocation. In one case, an additional focus of D15Z1 hybridization was seen on 21p.

Child, Preschool↗
PubMed1993

Three patients with ring (X) chromosomes and a severe phenotype.

Three patients with mosaicism and a cell line containing a small ring (X) chromosome are described. Their phenotype is similar to several previously reported patients with a 45,X/46,X,r(X) karyotype and a phenotype far more severely affected than expected in Turner's syndrome. The clinical picture includes mental retardation, a facial appearance reminiscent of the Kabuki make up syndrome, and limb anomalies. Some of the patients also had streaky hyperpigmentation of the skin in a pattern suggesting dermal mosaicism. It has been hypothesised that the severe phenotype might be the result of the small r(X) chromosome remaining active. However, there is little critical evidence to support this suggestion, while there is considerable evidence against it, including (1) a similar phenotype in 45,X/46,X,r(Y) patients, (2) the late replication of some of the small r(X) chromosomes associated with this phenotype, and (3) the expression of XIST in some of the affected patients.

Dosage Compensation, Genetic↗
PubMed1992

A non-isotopic in situ hybridisation study of the chromosomal origin of 15 supernumerary marker chromosomes in man.

Fifteen patients presenting with mosaic or non-mosaic karyotypes containing a distamycin-DAPI negative de novo or familial supernumerary marker chromosome were studied with non-isotopic in situ hybridisation using a library of alphoid centromere specific and satellite II/III probes. The in situ hybridisation studies showed that seven markers were derived from satellited autosomes (three chromosome 13/21, two chromosome 14, two chromosome 22), six from non-satellited autosomes (two chromosome 4, one chromosome 12, one chromosome 16, two chromosome 19), and one from the Y chromosome. One non-mosaic marker was negative for all the alphoid and satellite II/III probes used.

Abnormalities, Multiple↗
PubMed1991

A test of the production line hypothesis of mammalian oogenesis.

Germ cells in female mammals become committed to meiosis and enter its prophase sequentially in fetal life and, according to the Production Line Hypothesis, the oocytes thus generated are released after puberty as mature ova in the same sequence as that of meiotic entry in fetu. This hypothesis in its original and complete form has a subordinate proposition that concerns chiasma (Xma) frequency; it postulates that Xma number would decrease with fetal age. Consequently, univalents would increase, leading to errors of chromosome disjunction at the first meiotic division (MI), and thus to maternal age-dependent numerical chromosome anomalies. By using an in vitro/in vivo approach, we radioactively labelled the DNA of germ cells at premeiotic synthesis as they sequentially entered meiosis, while the fetal ovaries were in culture. At the end of this in vitro phase, pachytene/diplotene (P/D) stages were studied to determine their labelled fraction. The ovaries were then transplanted to spayed females and, after the in vivo phase, mature ova were harvested and the proportion of labelled first and second meiotic metaphases (MI/MII) determined. By marking the germ cells with label while in vitro during periods equivalent to early and late gestation, and by comparing the observed proportions of labelled MI/MII with those of oocytes labelled at P/D, we concluded that, in the mouse, ova do not mature at random for release, but are formed according to a production line system in which the time of release after puberty is related to the time of entry into meiosis in fetu.

Animals↗
PubMed1991

An investigation of ring and dicentric chromosomes found in three Turner's syndrome patients using DNA analysis and in situ hybridisation with X and Y chromosome specific probes.

We have studied three patients with features of Turner's syndrome, two with a 45,X/46,X,r(?) and the third with a 45,X/46,X,dic?(Y) karyotype. Because Turner's syndrome patients with a mosaic karyotype containing a Y chromosome are known to have a high risk of developing gonadal tumours, we used DNA analysis and in situ hybridisation with X and Y specific probes to identify the chromosomal origin of the rings and dicentric chromosomes in the three index patients. Both ring chromosomes were shown to be of X origin, while the dicentric was composed of Y chromosome material. We discuss the importance of using a combination of molecular and cytogenetic analyses in such cases.

Adolescent↗
PubMed1990

The induction of tail malformations in trisomy 16 mouse fetuses heterozygous for the curly tail recessive gene.

The mouse mutant curly tail is thought to be inherited as an autosomal recessive (ct/ct) with incomplete penetrance so that approximately 60% of ct/ct individuals exhibit the curly tail (CT) phenotype. By outcrossing ct/ct with mouse stock carrying specific heterozygous combinations of Robertsonian (Rb) chromosomes, trisomy 16 (Ts16) and Ts19 mouse fetuses (and their chromosomally balanced littermates) were derived which were heterozygous for the ct gene. All of the Ts16 (ct/Rb;Rb) fetuses, studied between days 14-19 gestation had tail malformations, 86% of which were tail flexion defects (TFD) apparently very similar to the curly tail phenotype. Neither Ts19 nor any of the chromosomally balanced (ct/Rb) littermates from both experimental crosses showed any type of tail or other spinal malformation. At the 27-29 somite stage of development, Ts16 (ct/Rb;Rb) fetuses did not show any significant delay in the closure of the posterior neuropore (PNP) compared with their littermate controls, suggesting that the tail malformation observed in Ts16 (ct/Rb;Rb) occur as a result of mechanisms which differ significantly from those thought to be responsible to causing the curly tail malformation.

Animals↗
PubMed1990

Spontaneous induction of an homologous robertsonian translocation, Rb(11.11) in a murine embryonic stem cell line.

Karyotype analysis of a series of established mouse embryonic stem cell (MESC) lines showed that the majority were aneuploid by the 7th and 9th passage and that all lines contained a single Robertsonian (Rb) translocation chromosome with a symmetrical, homologous, arm composition Rb(11.11). Although the chromosomal imbalance makes these MESC lines unsuitable for genetic manipulation in vitro and hence for subsequent production of transgenic animals, the spontaneous occurrence and stable retention of the homologous Rb(11.11) as the only metacentric chromosome in an otherwise all acrocentric karyotype, provides potentially useful cell lines for gene assignment and recombinant DNA studies.

Animals↗
PubMed1990

A cytogenetic and molecular reappraisal of a series of patients with Turner's syndrome.

The results of a cytogenetic and molecular reinvestigation of a series of 52 patients with Turner's syndrome are reported. No evidence of Y chromosome material was found among the patients with a 45,X constitution but two patients were found to have a cell line with a r(Y) chromosome which was previously thought to be a r(X). The parental origin of the single X in the 45,X patients was maternal in 69% and paternal in 31%, a similar ratio to that seen among spontaneously aborted 45,X conceptuses. This suggests that X-chromosome imprinting is not responsible for the two grossly different phenotypes associated with a 45,X chromosome constitution. Approximately half of the structurally abnormal X chromosomes were maternal in origin and half paternal. This observation is consistent with either a meiotic or post-zygotic mitotic origin and at variance with the predominantly paternal origin reported for autosome structural abnormalities.

Adolescent↗
PubMed1989

Incontinentia pigmenti and X-autosome translocations. Non-isotopic in situ hybridization with an X-centromere-specific probe (pSV2X5) reveals a possible X-centromeric breakpoint in one of five published cases.

Incontinentia pigmenti (IP) is a rare X-linked disease with marked female-to-female transmission and a dominant pattern of inheritance. Reports of six unrelated females with IP and X-autosomal translocations, all with the X breakpoint at Xp11, and an additional report of a female with IP and a 45,X/46,X,r(X) karyotype suggests that this may be the locus for the IP gene. When four of these cases, including the r(X), were re-examined with a non-isotopic in situ hybridization technique and an X centromere-specific probe (pSV2X5), the Xp11 breakpoint was confirmed. However, results from a fifth reported case, t(X;17), showed that the X breakpoint was within the centromeric alphoid repetitive sequences recognized by the probe pSV2X5. As the clinical presentation of this patient was consistent with the IP phenotype and diagnosis, the centromeric position of the X-chromosome breakpoint raises several questions with respect to the homogeneity of the Xp11 locus for IP.

Centromere↗
PubMed1989

Meiosis in trisomic female mice with Robertsonian translocations. I. Prophase pairing.

The prophase oocytes of two murine Robertsonian translocation (Rb) trisomies of chromosomes 16 and 19 were investigated using electron microscopy and a whole-cell micro-spreading technique after silver staining. About 20% of fetuses of each type were trisomic. They were obtained by mating animals heterozygous for two Rb's, monobrachially homologous for either chromosome 16 or 19, to an entirely acrocentric stock. Because of the almost inevitable prenatal mortality of the trisomic embryos, their fetal ovaries were "rescued" by an in vitro method for prophase studies. Analysis of the recovered oocytes showed frequent, close pairing associations of the three trisomic axes and evidence suggesting that the closely apposed axes coincided with the side-by-side formation of parallel, complete, true synaptonemal complexes; hence, the cytogenetic dogma that pairing is always two-by-two was contradicted. The presence of two parallel complexes has implications for crossing-over recombination. Triple associations of axes were found in almost half the trisomy 19 (Ts19) and in about 70% of the trisomy 16 (Ts16) prophases. The extent of triple associations varied and was greater in Ts16 than in Ts19 oocytes. Other relevant observations concerned the proportions of univalents and of univalence of the trisomic axes (21% in Ts16 and 46% in Ts19) and the distinctive, thickened appearance of all univalent axes. The pairing behaviour observed in balanced heterozygotes confirms what appears to be nonhomologous pairing and synaptic adjustment within the short-arm axes of the Rb trivalents.

Animals↗
PubMed1989

Meiosis in trisomic female mice with Robertsonian translocations. II. Chromosome behaviour at first and second meiotic metaphases.

First and second meiotic metaphases (MI and MII, respectively) from female mice of Robertsonian translocation (Rb) stock, trisomic for chromosome 16 (Ts16) or 19 (Ts19), were studied. The mature trisomic oocytes were derived from explanted fetal ovaries that had been cultured and then transplanted so as to mature heterotopically. Multivalent configurations involving the Rb chromosomes and the additional trisomic acrocentric were analysed. Pentavalent configurations occurred in 74.5% of 98 Ts16 MI and 44.2% of 249 Ts19 MI oocytes; quadrivalents (with a univalent acrocentric) were found in 9.2% of Ts16 MI and 10.8% of Ts19 MI oocytes. In 1% of Ts16 MI and 4% of Ts19 MI oocytes, there were two Rb bivalents and a univalent trisomic acrocentric. Rb trivalents and Rb bivalents occurred together in 14.3% of Ts16 MI and 39.4% of Ts19 MI oocytes. Chiasma frequencies were similar in trisomic and chromosomally balanced MI. Chiasma position, distribution, and localization were nearly identical, whether they were found in Rb multivalents or acrocentric bivalents, but one control group (from chromosomally balanced Ts19 littermates) had significantly more terminal chiasmata. Within the triple homologous region of 8% of Rb pentavalents, two chiasmata were observed in the same relative position in the two sister chromatids of one of the three homologs, suggesting a lapse in chiasma position interference. Assortment at MI anaphase was influenced by secondary nondisjunction of the Rb. The ratio of balanced to unbalanced MII oocytes was 1:4 in both trisomies.

Animals↗
PubMed1988

A mosaic 45,X/46,X,r(?) karyotype investigated with X and Y centromere-specific probes using a non-autoradiographic in situ hybridization technique.

The sex-chromosomal origin of the ring chromosome in a pre-pubertal non-virilized female patient presenting with a 45,X/46,X,r(?) karyotype could not be resolved by conventional cytogenetic (including G11) methods. Non-autoradiographic in situ hybridization of biotinylated X and Y centromere-specific alphoid repetitive sequence probes unequivocally and rapidly identified the ring to be of X origin.

Adolescent↗