Integrity of the thyroglobulin locus in tricho-rhino-phalangeal syndrome II

Summary The thyroglobulin gene has been mapped to chromosome band 8q24 by several investigators. This is the band implicated in the causation of Langer-Giedion syndrome (tricho-rhino-phalangeal syndrome II). We have examined a restriction fragment length polymorphism at the thyroglobulin locus in a patient with Langer-Giedion syndrome and 8q deletion in order to: (1) localize the Langer-Giedion deletion more precisely, (2) define the relative map positions of the thyroglobulin gene and the Langer-Giedion locus. The results indicate that the locus of the thyroglobulin gene is intact in the patient with an interstitial deletion of proximal band 8q24.1 which confirms its more distal localization reported earlier by Bergé-Lefranc et al. (1985). It also assigns the critical region for the causation of Langer-Giedion syndrome to the proximal part of band 8q24, viz. 8q24.11q24.13.     

Langer-Giedion syndrome,in a child with complex structural aberration of chromosome 8

A patient with typical features of the Langer-Giedion syndrome (tricho-rhino-phalangeal syndrome, type II) is described. In the karyotype an interstitial deletion of the long arm of chromosome 8 (band 8q22) was observed as the result of a complex rearrangement of chromosomes 1 and 8: 46,XY inv(8)(q23 leads to q242), del(8)(q221 leads to q223), ins(8;1) (q221;p321 p341;q242). Previously reported cases of Langer-Giedion syndrome with deletion of 8q are compared with the present one.     

The critical segment for the Langer-Giedion syndrome: 8q24.11----q24.12

An 18-year-old intellectually normal male with characteristic features of the Langer-Giedion syndrome is reported. High resolution chromosome analysis showed a small deletion in the region of bands 8q24.11 and 8q24.12 in addition to an apparently balanced de novo translocation (2;9)(q21;q13). This finding provides additional information on the minimum deleted segment required to produce the Langer-Giedion syndrome and may indicate that deletions of this size or smaller are not necessarily associated with mental retardation.     

Langer-Giedion syndrome associated with submucous cleft palate

We report a 4-year-old girl with characteristic features of the Langer-Giedion syndrome (trichorhinophalangeal syndrome type II) who also had submucous cleft palate. When she underwent a palatoplasty, a diagnosis of Langer-Giedion syndrome was made because of the characteristic facial features, multiple exostoses, and partial deletion of the long arm of chromosome 8. This is the first case of trichorhinophalangeal syndrome associated with cleft palate. We review the clinical alterations of trichorhinophalangeal syndromes and differential diagnosis of Langer-Giedion syndrome from trichorhinophalangeal syndrome type I and hereditary multiple exostoses. We also describe the importance of trichorhinophalangeal syndrome in plastic surgery.     

Molecular analysis of overlapping chromosomal deletions in patients with Langer-Giedion syndrome.

We have obtained lymphoblastoid cell lines from three patients with Langer-Giedion syndrome who have overlapping deletions in 8q24.1. To isolate the deletion chromosomes from their normal homologs, patient cell lines were fused with hamster cells and hybrid cells were selected for retention of human chromosome 8. These hybrid cell lines were screened for the presence of chromosome 8 by fluorescence in situ hybridization and by Southern blot hybridization. We have hybridized 31 recombinant DNA clones derived from the 8q22-qter region to Southern blots of the hybrid cell lines; 8 were found to lie within the deletion of at least one patient. One clone identified sequences that were missing from one copy of chromosome 8 in all three patients. These clones help to further define the deletions in these patients and will serve as starting points for detailed characterization of the region.     

The tricho-rhino-phalangeal syndromes: frequency and parental origin of 8q deletions

The tricho-rhino-phalangeal syndromes type I (TRPS I) and type II (TRPS II) result from the deletion of overlapping sets of genes within the Langer-Giedion syndrome chromosomal region (LGCR) on chromosome 8. In contrast to TRPS I patients, most TRPS II patients have cytogenetically visible deletions and are often mentally retarded. Using Southern blot and fluorescence in situ hybridization analysis, we searched for submicroscopic deletions in 12 patients with TRPS I and an apparently normal karyotype. One patient of normal intelligence was found to have a deletion of approximately 5 Mb. This suggests that mental retardation in TRPS is caused by genes outside the 5-Mb region. Using three LGCR microsatellite markers, we determined the parental origin of this TRPS I deletion and of eight TRPS II deletions. In six patients, the deletion was of paternal origin and in three patients it was of maternal origin. Received: 6 September 1996 / Revised: 20 November 1996     

An integrated physical map of 8q22-q24: use in positional cloning and deletion analysis of Langer-Giedion syndrome

We have developed an integrated map for a 35-cM area of human chromosome 8 surrounding the Langer-Giedion syndrome deletion region. This map spans from approximately 8q22 to 8q24 and includes 10 hybrid cell intervals, 89 polymorphic STSs, 118 ESTs, and 37 known genes or inferred gene homologies. The map locations of 25 genes including osteoprotegerin, syndecan-2, and autotaxin have been refined from the general locations previously reported. In addition, the map has been used to indicate the location of nine deletions in patients with Langer-Giedion syndrome and trichorhinophalangeal syndrome type I to demonstrate the potential usefulness of the map in the analysis of these complex syndromes. The map will also be of interest to anyone trying to clone positionally disease genes in this region, such as Cohen syndrome (8q22-q23), Klip-Feil syndrome (8q22.2), hereditary spastic paraplegia (8q24), and benign adult familial myoclonic epilepsy (8q23.3-q24.1).     

Characterization of deletions in common wheat induced by an Aegilops cylindrica chromosome: detection of multiple chromosome rearrangements

An Aegilops cylindrica chromosome induces terminal deletions of chromosomes in wheat as identified by C-banding. We are constructing high-density physical maps of wheat chromosomes and have detected additional chromosome rearrangements. Among 63 lines with chromosomal subarm deletions in group 7 chromosomes, 7 lines (11.1%) were shown to harbor additional chromosome rearrangements. Two other lines were also omitted from the physical mapping because of the nature of the breakpoint calculations. The presence or absence of chromosome-specific restriction fragment length polymorphism (RFLP) or random amplified polymorphic DNA (RAPD) markers indicated that additional interstitial deletions are present in 3 lines (4.8%) with deletions in the short chromosome arms and in 4 lines (6.3%) with deletions in the long chromosome arms. We also used chromosome pairing analysis of F₁ plants of deletion lines with double ditelosomic lines of Chinese Spring wheat to detect small terminal deletions. The deletion of the most distal 1% of chromosome arm 7AL was associated with a pairing reduction of 60%.     

Characterization of a Recombinant Mouse t Haplotype That Expresses a Dominant Lethal Maternal Effect

The t^wLub2 chromosome was generated by rare recombination between a complete t haplotype and a wild-type form of mouse chromosome 17. This recombinant chromosome expresses a dominant lethal effect in all embryos that inherit the mutant chromosome from their mothers. The phenotype of this maternal effect is indistinguishable from that expressed by the previously described T^hp deletion chromosome. It appears likely that the crossing over event that gave rise to t^wLub2 was unequal and resulted in the alteration or deletion of a gene (which is named the T-associated maternal effect locus, Tme) that must be inherited from the mother in order for normal development to proceed through late stages of gestation. The results presented here allow a mapping of the Tme locus between the quaking and tufted loci which are 3 cM apart within the proximal region of chromosome 17.     

Altered Ultrasonic Vocalization and Impaired Learning and Memory in Angelman Syndrome Mouse Model with a Large Maternal Deletion from Ube3a to Gabrb3

Angelman syndrome (AS) is a neurobehavioral disorder associated with mental retardation, absence of language development, characteristic electroencephalography (EEG) abnormalities and epilepsy, happy disposition, movement or balance disorders, and autistic behaviors. The molecular defects underlying AS are heterogeneous, including large maternal deletions of chromosome 15q11–q13 (70%), paternal uniparental disomy (UPD) of chromosome 15 (5%), imprinting mutations (rare), and mutations in the E6-AP ubiquitin ligase gene UBE3A (15%). Although patients with UBE3A mutations have a wide spectrum of neurological phenotypes, their features are usually milder than AS patients with deletions of 15q11–q13. Using a chromosomal engineering strategy, we generated mutant mice with a 1.6-Mb chromosomal deletion from Ube3a to Gabrb3, which inactivated the Ube3a and Gabrb3 genes and deleted the Atp10a gene. Homozygous deletion mutant mice died in the perinatal period due to a cleft palate resulting from the null mutation in Gabrb3 gene. Mice with a maternal deletion (m−/p+) were viable and did not have any obvious developmental defects. Expression analysis of the maternal and paternal deletion mice confirmed that the Ube3a gene is maternally expressed in brain, and showed that the Atp10a and Gabrb3 genes are biallelically expressed in all brain sub-regions studied. Maternal (m−/p+), but not paternal (m+/p−), deletion mice had increased spontaneous seizure activity and abnormal EEG. Extensive behavioral analyses revealed significant impairment in motor function, learning and memory tasks, and anxiety-related measures assayed in the light-dark box in maternal deletion but not paternal deletion mice. Ultrasonic vocalization (USV) recording in newborns revealed that maternal deletion pups emitted significantly more USVs than wild-type littermates. The increased USV in maternal deletion mice suggests abnormal signaling behavior between mothers and pups that may reflect abnormal communication behaviors in human AS patients. Thus, mutant mice with a maternal deletion from Ube3a to Gabrb3 provide an AS mouse model that is molecularly more similar to the contiguous gene deletion form of AS in humans than mice with Ube3a mutation alone. These mice will be valuable for future comparative studies to mice with maternal deficiency of Ube3a alone.     

An interleukin-8 (IL-8) cDNA clone identifies a frequent HindIII polymorphism

An interleukin-8 cDNA probe detects a biallelic HindIII polymorphism. This frequent restriction fragment length polymorphism (RFLP) provides a new genetic marker for the long arm of chromosome 4.     

De novo complex autosomal translocation involving chromosomes 8, 13 and 15 in a girl with a sporadic retinoblastoma

Summary We report a case of a 5-month-old female with sporadic monolateral retinoblastoma (RB) with a constitutional de novo complex autosomal translocation involving chromosomes 8, 13 and 15 resulting in a deletion of chromosome 13q14 confirmed by esterase D assay. The translocation of the terminal portion of chromosome 8 has been observed by in situ hybridization with c-myc and thyroglobulin probes.     

Routine screening for microdeletions by FISH in 77 patients suspected of having Prader-Willi or Angelman syndromes using YAC clone 273A2 (D15S10)

About 70% of patients with Prader-Willi syndrome (PWS) and Angelman syndrome (AS) have a common interstitial de novo microdeletion encompassing paternal (PWS) or maternal (AS) loci D15S9 to D15S12. Most of the non-deletion PWS patients and a small number of non-deletion AS patients have a maternal or paternal uniparental disomy (UPD)15, respectively. Other chromosome 15 rearrangements and a few smaller atypical deletions, some of the latter being associated with an abnormal methylation pattern, are rarely found. Molecular and fluorescence in situ hybridization (FISH) analysis have both been used to diagnose PWS and AS. Here, we have evaluated, in a typical routine cytogenetic laboratory setting, the efficiency of a diagnostic strategy that starts with a FISH deletion assay using Alu-PCR (polymerase chain reaction)-amplified D15S10-positive yeast artificial chromosome (YAC) 273A2. We performed FISH in 77 patients suspected of having PWS (n = 66) or AS (n = 11) and compared the results with those from classical cytogenetics and wherever possible with those from DNA analysis. A FISH deletion was found in 16/66 patients from the PWS group and in 3/11 patients from the AS group. One example of a centromere 15 co-hybridization performed in order to exclude cryptic translocations or inversions is given. Of the PWS patients, 14 fulfilled Holm’s criteria, but two did not. DNA analysis confirmed the commmon deletion in all patients screened by the D15S63 methylation test and in restriction fragment length polymorphism dosage blots. In 3/58 non-deletion patients, other chromosomal aberrations were found. Of the non-deleted group, 27 subjects (24 PWS, 3 AS) were tested molecularly, and three patients with an uniparental methylation pattern were found in the PWS group. The other 24/27 subjects had neither a FISH deletion nor uniparental methylation, but two had other cytogenetic aberrations. Given that cytogenetic analysis is indispensable in most patients, we find that the FISH deletion assay with YAC 273A2 is an efficient first step for stepwise diagnostic testing and mutation-type analysis of patients suspected of having PWS or AS. Received: 14 November 1995     

Origin of an alien disomic addition with an aberrant homologue of chromosome-10 of tomato and its meiotic behaviour in a potato background revealed through GISH

 While characterising potato (Solanum tuberosum, 2n=4x=48) clones with alien tomato (Lycopersicon esculentum) chromosome additions, a single addition for chromosome-10 of tomato was identified through restriction fragment length polymorphism (RFLP) analysis. This plant, 2101–1, was a BC₂ derivative from a cross between a potato (+) tomato fusion hybrid backcrossed to potato. Cytological analysis of its somatic chromosomes through genomic in situ hybridisation (GISH) indicated the presence of four genomes of potato with two alien tomato chromosomes, of which one was much smaller than the other. Analysis of chromosome pairing at the pachytene and metaphase-I stages of microsporogenesis indicated that the large and small chromosomes were homologues. Thus, it was a disomic addition for chromosome-10 of tomato. The size difference was found to be due to a deletion. Fluorescent in situ hybridisation (FISH) experiments, using the telomeric repeat pAtT4 from Arabidopsis thaliana and the sub-telomeric repeat TGRI, showed intact telomeres and sub-telomeres for both alien chromosomes. Thus, the deletion that the smaller of the homologues suffered was interstitial and most probably occurred in the centromeric heterochromatic region of the long arm. The pattern of distribution of large and small chromosomes to telophase-II nuclei during microsporogenesis indicated that the deletion did not affect the meiotic behaviour of the smaller chromosome. In contrast, the frequencies of transmission of the large and the small chromosomes through the female parent, estimated in 96 BC₃ progeny of plants by RFLP and GISH analyses, appeared to be very different, 69.2% and 3.8% respectively. This study also provides evidence that two different chromatids of a pair of homologues, rather than two chromatids of a single chromosome, are most likely to be involved in the origin of a disomic. The aberrant chromosome can be used for the physical mapping of chromosome-10. Received: 9 June 1998 / Accepted: 28 October 1998     

Angelman syndrome in an inbred family

Angelman syndrome (AS) is characterized by severe mental retardation, absent speech, puppet-like movements, inappropriate laughter, epilepsy, and abnormal electroencephalogram. The majority of AS patients ( 65%) have a maternal deficiency within chromosomal region 15q11–q13, caused by maternal deletion or paternal uniparental disomy (UPD). Approximately 35% of AS patients exhibit neither detectable deletion nor UPD, but a subset of these patients have abnormal methylation at several loci in the 15q11–q13 interval. We describe here three patients with Angelman syndrome belonging to an extended inbred family. High resolution chromosome analysis combined with DNA analysis using 14 marker loci from the 15q11-q13 region failed to detect a deletion in any of the three patients. Paternal UPD of chromosome 15 was detected in one case, while the other two patients have abnormal methylation atD15S9, D15S63, andSNRPN. Although the three patients are distantly related, the chromosome 15q11-q13 haplotypes are different, suggesting that independent mutations gave rise to AS in this family.     

Langer-Giedion syndrome and deletion of the long arm of chromosome 8

Summary Reexamination of a previously reported patient with 8q interstitial deletion reveals the development of a tricho-rhinophalangeal syndrome type II (Langer-Giedion syndrome) with multiple exostoses at the age of 4 years. Together with the two previous reports on 8q deletion and TRP II syndrome the present observation strongly supports the causal relationship between TRP II syndrome and 8q deletion.     

High-resolution cytological mapping of the long arm of chromosome 5A in common wheat using a series of deletion lines induced by gametocidal (Gc) genes of Aegilops speltoides

Gametocidal (Gc) genes of Aegilops in the background of the wheat genome lead to breakage of wheat chromosomes. The Q gene of wheat was used as a marker to select 19 deletion lines for the long arm of chromosome 5A of common wheat, Triticum aestivum cv. Chinese Spring (CS). The extents of deleted segments were cytologically estimated by the C-banding technique. The DNAs of deletion lines were hybridized with 22 DNA probes recognizing sites on the long arm of the chromosome (5AL) to determine their physical order. Based on the breeding behavior of the deletion lines, the location of a novel gene (Pv, pollen viability) affecting the viability of the male gamete was deduced. The segment translocated from 4AL to 5AL in CS was cytologically estimated to represent 13% of the total length of 5AL. Although DNA markers were almost randomly distributed along the chromosome arm, DNA markers located around the centromere and C-banded regions were obtained only rarely. Some deletion lines were highly rearranged in chromosome structure due to the effect(s) of the Gc gene. Applications of Gc genes for manipulating wheat chromosomes are discussed.     

AFLP and STS tagging of Lr19, a gene conferring resistance to leaf rust in wheat

Amplified fragment length polymorphism (AFLP) markers were used to enrich the map of the wheat chromosomal region containing the Thinopyrum-derived Lr19 leaf rust resistance gene. The region closest to Lr19 was targeted through the use of deletion and recombinant lines of the translocated segment. One of the AFLP bands thus identified was converted into a sequence-tagged-site (STS) marker. This assay generated a 130-bp PCR fragment in all Lr19-carrying lines tested, except for one deletion mutant, while non-carrier template failed to amplify any product. This sequence represents the first marker to map on the distal side of Lr19 on chromosome 7el₁. The conversion process of AFLP fragments to STS markers was technically difficult, mainly because of the presence of contaminating fragments. Various approaches were taken to reduce the frequency of false positives and to identify the correct clone. We were able to formulate a general verification strategy prior to clone sequencing. Various other factors causing problems with converting AFLP bands to an STS assays are also discussed. Received: 15 September 2000 / Accepted: 5 January 2001     

DNA addition or deletion is associated with a major karyotype polymorphism in the fungal phytopathogen Colletotrichum gloeosporioides

Summary A 1.2 Mb minichromosome resolved by pulsed-field electrophoresis was present in two independent race 3 isolates of Colletotrichum gloeosporioides causing Type B anthracnose specifically on Stylosanthes guianensis cv. Graham in Australia. This chromosome was absent in duplicate isolates representing races 1, 2 and 4 which infect other S. guianensis cultivars. A gene library was prepared specifically from the 1.2 Mb mini-chromosome and ten independent DNA clones unique to this chromosome were identified by differential hybridisation to whole chromosome probes. All of the ten selected probes hybridised only to the 1.2 Mb minichromosome unique to the race 3 isolates but not to any chromosome in isolates of the other races. These ten probes also hybridised only to restriction-digested DNA of race 3 and were thus both chromosome- and strain-specific for Type B C. gloeosporioides. Hybridisation analysis of NotI fragments of the 1.2 Mb minichromosome with these sequences indicated that they were not tightly clustered on the chromosome. These data demonstrate that the variation in the occurrence of the 1.2 Mb minichromosome did not arise by rearrangement of the genome of a progenitor strain but involved either large scale deletion or addition of DNA. The 1.2 Mb minichromosome did not contain a cloned high-copy-number repeat sequence present on all other mini- and maxichromosomes, suggesting addition from a genetically distinct strain. All ten chromosome-specific DNA probes hybridised to a 2.0 Mb chromosome in all races of C. gloeosporioides causing Type A anthracnose on Stylosanthes spp. including S. guianensis. Restriction fragment length polymorphism analysis demonstrated that only 15% of the hybridising restriction fragments of the Type A 2.0 Mb chromosome and the 1.2 Mb Type B race 3 minichromosome were identical. This indicated that it is unlikely that the 1.2 Mb minichromosome of the race 3 Type B pathogen was recently introgressed from-the Type A pathogen.