TAR-cloning of the short arm of human chromosome 7 in yeast and search for terminal sequences

A partial clone library of the short arm of human chromosome 7 was created in yeast artificial chromosomes (YAC) using TAR-cloning. The DNA of monochromosome somatic hybrid cells (mouse/human) RuRag 14-4-7-44 containing short arm human chromosome 7 was used for cloning. The clone library was screened for YACs with the human DNA; the mitotic stability of these YACs, the sizes of cloned fragments, and an independent clonal distribution in the chromosome were determined. Human YACs were tested for the presence of chromosome 7p telomeric sequences.     

Chromosome 7 short arm deletion and craniosynostosis a 7p-syndrome

Summary A patient with craniosynostosis and a small deletion of part of the short arm of chromosome 7 is described. A review of the literature indicates that craniosynostosis has occurred in at least four of the five infants (the fifth having microcephaly) affected by structural changes (resulting in deletion) within the terminal region of the short arm of chromosome 7.Supported by: National Foundation March of Dimes Grant CA-90, National Institutes of Health Grants, No. 5S01 RR05655-07 and No. P01 GM 15 253-08     

Relationship between Chromosome 9 of Maize and Wheat Homeologous Group 7 Chromosomes

Comparison of the genetic map of maize chromosome 9 with maps of wheat chromosomes has revealed a high degree of colinearity between maize chromosome 9 and the group 4 and 7 chromosomes of wheat. The order of DNA markers on the short arm and a proximal region of the long arm of the genetic map of maize chromosome 9 is highly conserved with the marker order on the short arm and proximal region of the long arm of the genetic maps of the wheat homeologous group 7 chromosomes. A major part of the long arm of the genetic map of maize chromosome 9 is homeologous with a short segment in the proximal region of the long arm of the genetic map of the wheat group 4 chromosomes. Evidence is also presented that maize chromosome 9 has diverged from the wheat group 7 chromosomes by both a pericentric and a paracentric inversion. The paracentric inversion is probably unique to maize among the major cereal genomes.     

Response of Barley Lines with Structural Rearrangements in Chromosomes 5, 6 and 7 to Limited Nitrogen Nutrition

The responses of barley (Hordeum vulgare L.) lines with rebuilt chromosomes 5, 6 and 7 to reduced nitrogen nutrition were evaluated in juvenile growth stages. The material included two series of duplications (D) produced in the short arm of chromosome 6 and of chromosome 7, and in the long arm of chromosome 5 and of chromosome 6; their parental translocation lines (T) - from which analyzed duplications were derived and a standard karyotype cv. Bonus as a control. The translocation lines have break points located in 6_S and 7_S, or 5_L and 6_L. Only the lines with duplicated segments of the short arms of satellited (6 and 7) chromosomes exhibited an improved tolerance to reduced nitrogen supply. No changes relative to cv. Bonus were observed in the T-lines. More tolerant D-lines showed lower stimulation of the root development. Obtained results suggests that the adaptability factors for the low N tolerance at the vegetative growth stage of barley are located in the short arms of 6 and 7 chromosomes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Molecular mapping of the photoperiod response gene ea7 in barley

 The gene ea ₇ determining photoperiod insensitivity under short day length was mapped on the short arm of chromosome 6H near the centromere. The gene was linked to the two flanking markers Xmwg2264 and Xmwg916 by 6.7 and 13.0 cM, respectively. Compared to Ppd-H1 (chromosome 2H) and Ppd-H2 (chromosome 1H), ea ₇ determines the strongest effect on flowering time with 55 and 18 days difference compared to photoperiod sensitive genotypes grown under short and long photoperiods, respectively. Allelic and homoeologous relationships to major genes and quantitative trait loci controlling flowering time in barley and wheat are discussed. Received: 10 March 1998 / Accepted: 7 April 1998     

Partial trisomy 7q in two siblings

Trisomy for 7q32 leads to 7qter and monosomy for 9p24 leads to 9pter is observed in a sister and a brother, due to a balanced reciprocal translocation between the long arm of the chromosome 7 and the short arm of the chromosome 9 in the mother. The siblings are retarded mentally as well as in statomotoric development. This paper discusses the correlation between chromosomal states and certain deformities in patients with trisomies of different segments of 7q.     

Translocation +(7p+; Bq-) associated with recurrent abortion.

A balanced translocation was found in a normal female with a history of four abortions. On the basis of the Giemsa-banding pattern the abnormality was interpreted as to be a translocation of a part of the long arm of chromosome 13 to the short arm of chromosome some 7:t(7;13)(7qter leads to 7p22::13q14 leads to 13qter;13q14 leads to 13pter::7p22 leads to 7 pter). Problems in genetic counseling are discussed with respect to this case.     

Regional mapping on human genes for phosphoglucomutase-1 on chromosome 1 and beta-glucuronidase on chromosome 7 using mouse x human hybrids.

Two independent mouse-human somatic cell hybrid clones contained different, de novo chromosome rearrangements involving the short arm of human chromosome 1. One hybrid clone contained a translocation between human chromosomes 1 and 7; the other clone contained a rearrangement product between human chromosomes 1 and 14. Analysis of these clones for expression of genes previously assigned to chromosome 7 and to the short arm of chromosome 1 provided evidence for localization of PGM--1 in segment 1p22.1 leads to 1p31.1, AK--2, ENO--1 and UMPK in region 1pter leads to 1p31.1, and GUS in region 7 pter leads to 7q22. The results have been used to examine the relationship between cytologic and genetic map distances on the short arm of chromosome 1.     

Uniparental isodisomy for paternal 7p and maternal 7q in a child with growth retardation.

Uniparental isodisomy resulting from the simultaneous presence of isochromosomes of the p and q arms of a chromosome and absence of a normal homologue is an exceptionally rare event. We have observed a growth-retarded female infant in whom the normal chromosome 7 homologues were replaced by what appeared cytogenetically to be isochromosomes of 7p and 7q. Polymorphic microsatellite loci spanning the length of 7p and 7q were analyzed in the proband and her parents to ascertain the parental origin and extent of heterozygosity of the proband's rearranged chromosomes. These studies demonstrated that the 7p alleles of the proband were derived only from the father, the 7q alleles were derived only from the mother, and there was homozygosity for all chromosome 7 loci analyzed. The mechanisms leading to the formation of the proband's isochromosomes could reflect abnormalities of cell division occurring at meiosis, postfertilization mitosis, or both. We believe that the present case may result from incomplete mitotic interchange in the pericentromeric regions of chromosome 7 homologues, with resolution by sister-chromatid reunion in an early, if not first, zygotic division. Phenotypically, our proband resembled three previously reported cases of maternal isodisomy for chromosome 7, suggesting that lack of paternal genes from 7q may result in a phenotype of short stature and growth retardation.     

Chromosome 7 short-arm interstitial deletion (p14)

Summary A 13-year-old girl presented with microcephaly, short and broad neck, low posterior hairline, congenital heart disease, limitation of joint movement, and mild mental retardation. Chromosomal analysis showed interstitial deletion of band p14 of the short arm of chromosome 7. The patient's physical and cytogenetic findings are compared with those of five other patients with 7p-deletions.     

Mapping of locus for X-linked congenital stationary night blindness (CSNB1) proximal to DXS7.

A recombinant chromosome in a male affected with X-linked congenital stationary night blindness (CSNB1) provides new information on the location of the CSNB1 locus. A four-generation family with five males affected with X-linked CSNB was analyzed with five polymorphic markers for four X-chromosome loci spanning the region OTC (Xp21.1) to DXS255 (Xp11.22). Four of the males inherited the same X chromosome; one male inherited a chromosome that from OTC to DXS7, inclusive, was derived from the normal X chromosome of his unaffected grandfather and that from a location between DXS7 and DXS426 proximally was derived from the chromosome carrying the CSNB1 locus. This recombinant maps the CSNB1 locus in this family to a region on the short arm of the X chromosome proximal to the DXS7 locus.     

Duplication 7p de novo and literature review

We report on a boy with duplication of the short arm of chromosome 7 (karyotype 46,XY, dup (7) (p11.2----pter), QFQ, GTG, RBA). The boy showed delayed closure of fontanels, reduced eyebrows, short nose with low and broad nasal bridge, small upper and prominent full lower lips, severe delay of speech development. Comparison with the phenotype of 15 reported cases from the literature in relation to the extent of the duplicated segment did not show a clear phenotype/karyotype correlation.     

Comparison of wheat physical maps with barley linkage maps for group 7 chromosomes

Comparative genetic maps among the Triticeae or Gramineae provide the possibility for combining the genetics, mapping information and molecular-marker resources between different species. Dense genetic linkage maps of wheat and barley, which have a common array of molecular markers, along with deletion-based chromosome maps of Triticum aestivum L. will facilitate the construction of an integrated molecular marker-based map for the Triticeae. A set of 21 cDNA and genomic DNA clones, which had previously been used to map barley chromosome 1 (7H), were used to physically map wheat chromosomes 7A, 7B and 7D. A comparative map was constructed to estimate the degree of linkage conservation and synteny of chromosome segments between the group 7 chromosomes of the two species. The results reveal extensive homoeologies between these chromosomes, and the first evidence for an interstitial inversion on the short arm of a barley chromosome compared to the wheat homoeologue has been obtained. In a cytogenetically-based physical map of group 7 chromosomes that contain restriction-fragment-length polymorphic DNA (RFLP) and random amplified polymorphic DNA (RAPD) markers, the marker density in the most distal third of the chromosome arms was two-times higher than in the proximal region. The recombination rate in the distal third of each arm appears to be 8–15 times greater than in the proximal third of each arm where recombination of wheat chromosomes is suppressed.     

Molecular mapping of the centromeres of tomato chromosomes 7 and 9

The centromeres of two tomato chromosomes have been precisely localized on the molecular linkage map through dosage analysis of trisomic stocks. To map the centromeres of chromosomes 7 and 9, complementary telo-, secondary, and tertiary trisomic stocks were used to assign DNA markers to their respective chromosome arms and thus to localize the centromere at the junction of the short and long arms. It was found that both centromeres are situated within a cluster of cosegregating markers. In an attempt to order the markers within the centric clusters, genetic maps of the centromeric regions of chromosomes 7 and 9 were constructed from F₂ populations of 1620Lycopersicon esculentum × L. pennellii (E × P) plants and 1640L. esculentum × L. pimpinellifolium (E × PM) plants. Despite the large number of plants analyzed, very few recombination events were detected in the centric regions, indicating a significant suppression of recombination at this region of the chromosome. The fact that recombination suppression is equally strong in crosses between closely related (E × PM) and remotely related (E × P) parents suggests that centromeric suppression is not due to DNA sequence mismatches but to some other mechanism. The greatest number of centromeric markers was resolved in theL. esculentum × L. pennellii F₂ population. The centromere of chromosome 7 is surrounded by eight cosegregating markers: three on the short arm, five on the long arm. Similarly, the centric region of chromosome 9 contains ten cosegregating markers including one short arm marker and nine long arm markers. The localization of centromeres to precise intervals on the molecular linkage map represents the first step towards the characterization and ultimate isolation of tomato centromeres.     

Characterization of a 5HS-7DS.7DL wheat-barley translocation line and physical mapping of the 7D chromosome using SSR markers

A spontaneous wheat-barley translocation line was previously detected in the progenies of the Mv9kr1?×?‘Igri’ wheat-barley hybrid and the translocation was identified as 5HS-7DS.7DL. Multicolor genomic in situ hybridization (mcGISH) with D and H genomic DNA probes and three-color fluorescence in situ hybridization (FISH) with repetitive DNA probes (Afa-family, pSc119.2, and pTa71) were performed to characterize the rearranged chromosome. The effect of 5HS and the deleted 7DS fragment on the morphological traits (plant height, fertility, yield, and spike characteristics) of wheat was assessed. Despite the non-compensating nature of the translocation, the plants showed good viability. The aim of the study was to physically localize SSR markers to the telomeric and subtelomeric regions of the 7DS chromosome arm. Of the 45 microsatellite markers analyzed, ten (Xbarc0184, Xwmc0506, Xgdm0130, Xgwm0735, Xgwm1258, Xgwm1123, Xgwm1250, Xgwm1055, Xgwm1220, and Xgwm0635) failed to amplify any 7DS-specific fragments, signaling the elimination of a short chromosome segment in the telomeric region. The breakpoint of the 5HS-7DS.7DL translocation appeared to be more distal than that of reported deletion lines, which provides a new physical landmark for future deletion mapping studies.     

Pure interstitial duplication of chromosome 7q (7q31.2-->q33) in a 4-year-old girl with growth restriction, short stature, speech delay and intellectual disability

We report the cytogenetic and molecular characterization of a 22.3-Mb pure interstitial duplication of chromosome 7q, dup(7)(q31.2-->q33) in a 4-year-old girl with growth restriction, short stature, speech delay, inguinal hernia, strabismus and intellectual disability. We speculate that the gene dosage increase effect of the ING3 and LEP genes may be partially responsible for the phenotype of growth restriction and short stature in this patient.     

Interstitial deletion of the long arm of chromosome 7

Summary Chromosome studies were carried out in a girl because of psychomotor retardation and difficulty in swallowing. The girl was admitted to hospital for the first time when 25 months old. The most characteristic signs revealed by the physical examination were short distal ulnar phalanges, clitoral hypertrophy, and very thin outer ear cartilages.An interstitial deletion of the long arm of chromosome 7 was observed: 7q22::7q31.Laboratory investigations revealed a remarkably high level of IgG, immunoglobulin, and an elevated value of serum FSH. No evidence of gene loci located at the deleted part of chromosome 7 were found.     

A new case of pure partial 7q duplication

We report on an 18-month-old boy conceived by assisted reproduction technology with developmental delay, hypotonia, microcephaly, frontal bossing, a mild convergent squint, malformed ears, and a short neck. Karyotype analysis revealed a de novo 7q21.1q22.3 duplication characterized by array comparative genomic hybridization (array-CGH) as a segment of 18.69 Mb. Duplications of the long arm of chromosome 7 are uncommon. There are 18 reported cases of different 7q segments with a pure duplication with no additional deletion of other chromosomes. As a consequence, duplications of chromosome 7q have been classified in 4 groups on the basis of the involved region. The present case is included in group 3 which involves interstitial duplications of different sizes. In the literature, only one case with an apparently smaller duplication of the same region has been described. Despite this, the phenotype is different. Moreover, the 2 patients share some phenotypic features, such as psychomotor delay, hypotonia, frontal bossing, short neck, and strabismus. However, the absence of physical characterization in most of the reported cases could justify the lacking phenotype-genotype correlation in patients with partial 7q duplication. Further studies using recent molecular approaches such as array-CGH might permit a more clinically useful grouping of 7q duplications.