Adjacent 2 meiotic disjunction. Report of a case resulting from a familial 13q;15q balanced reciprocal translocation and review of the literature

Summary An abnormal short-lived female infant with almost complete trisomy 13 (pterq32 or 33) and partial monosomy 15 (pterq14 or 15) resulting from an adjacent 2 meiotic disjunction of a paternal reciprocal translocation is described. Cases with monosomy of chromosome 15 material are reviewed. It appears likely that monosomy of an interstitial long arm segment, approximating to 15q2124, imparts the lethality associated with the full monosomic condition. Adjacent 2 disjunction in man has been further characterised by reviewing the literature.     

Assignment of human phosphoribosylglycinamide synthetase locus to region 21q221

Summary The enzymatic activity of phosphoribosylglycinamide synthetase (GARS) has been studied in several cases of partial monosomies and full and partial trisomies 21. An excess of GARS activity was found in regular trisomy 21 with a trisomy 21/normal ratio equal to 1.55. A 0.99 ratio was found in 21q2121pter monosomy; a 0.54 ratio was found in 21qter21q22 monosomy; a 0.88 ratio, in 21q2121pter trisomy, and a 1.46 ratio, in 21q22.1 trisomy. Consequently, the GARS gene locus, assigned to chromosome 21, could be localized in subband 21q22.1.     

Regional mapping of liver type 6 phosphofructokinase isoenzyme on chromosome 21

Summary Among several cases of partial monosomies and full and partial trisomies 21, the enzymatic activity of phosphofructokinase (PFK) is increased only in 21q2121pter trisomy with a (T₂₁/N) ratio equal to 1.35 and decreased in monosomy 21q2121pter. These results suggest that the human gene for liver-type PFK is located between 21q21 and 21pter.     

Two unrelated children with partial trisomy 1q and monosomy 6p,presenting with the phenotype of the Larsen syndrome

Summary Two unrelated children presented with similar clinical features (facial dysmorphism and multiple joint dislocations) suggesting the diagnosis of Larsen syndrome. Both carried an inherited unbalanced translocation resulting in partial trisomy 1q and partial monosomy 6p. Analysis of skin collagen from one of the probands disclosed a decreased 1/2 chain ratio of collagen type I, increased thermal stability and increased hydroxylation of proline and lysine. The present findings suggest that, as a result of the chromosome rearrangements, both patients have a mutation on a gene involved in collagen production, located either on chromosome 1q or, more probably, on 6p. It is furthermore suggested that other cases of Larsen syndrome are the result of a similar mutation.     

Partial trisomy 6p

Summary A case of trisomy 6p216pter resulting from a maternal balanced t(2;6)(p25;p21) translocation is reported. The main clinical abnormalities were psychomotor retardation, hypotrophy, blepharophimosis, nystagmus, high nasal bridge, small mouth, sacral dimple, and systolic murmur. Other anomalies might have been due to partial 2p monosomy. Comparison with seven other cases of trisomy 6p allowed the delineation of a clinical entity. Direct proof of the localization of HLA genes was given by the presence of three haplotypes in the index patient.     

Are the nail-patella syndrome and the autosomal Goltz-like syndrome the phenotypic expressions of different alleles at the COL5A1 locus?

The COL5A1 gene, which encodes the pro 1(V) chain, was recently mapped to 9q34.3 in the same region as the nail-patella locus. This was taken as an indication that the nail-patella syndrome may be an inherited connective tissue disorder. We demonstrate COL5A1 heterozygous deletion and fibroblast under-expression of 1(V) chains in a girl with an unbalanced translocation resulting in 9q32qter monosomy. The patient presents dysplastic nails, a sign typical of nail-patella syndrome, but normal patella. Moreover, she has skin and bone disorders similar to those found in the Goltz syndrome. We suggest that monosomy for the COL5A1 gene is responsible for these connective tissue disorders. Accordingly, the nail-patella syndrome could be attributable to mutations inside the COL5A1 gene rather than to a deletion of it.     

Trisomy 16q23→qter arising from a maternal t(13;16)(p12;q23): case report and evidence of the reciprocal balanced maternal rearrangement by the Ag-NOR technique

Summary We describe a female new-born with partial trisomy of the long arm of chromosome 16. The chromosome anomaly was the result of an unbalanced segregation of a maternal translocation t(13;16)(p12;q23). Dynamic (RBG, GBG) banding and the Ag-NOR technique ascertained the reciprocal balanced maternal translocation between the 16q23qter and 13q12pter segments because nucleolar organizers were present on the tip of long arms of the derivative 16 maternal chromosome. As monosomy 13p has little or no deleterious effect we consider our case as exhibiting the phenotype of trisomy 16q23qter free from any monosomic feature. Clinical effects are of less consequence as compared with previously published cases of partial trisomy 16q.     

Impaired spatial learning strategies and novel object recognition in mice haploinsufficient for the dual specificity tyrosine-regulated kinase-1A (Dyrk1A)

Background

Pathogenic aneuploidies involve the concept of dosage-sensitive genes leading to over- and underexpression phenotypes. Monosomy 21 in human leads to mental retardation and skeletal, immune and respiratory function disturbances. Most of the human condition corresponds to partial monosomies suggesting that critical haploinsufficient genes may be responsible for the phenotypes. The DYRK1A gene is localized on the human chromosome 21q22.2 region, and has been proposed to participate in monosomy 21 phenotypes. It encodes a dual-specificity kinase involved in neuronal development and in adult brain physiology, but its possible role as critical haploinsufficient gene in cognitive function has not been explored.

Methodology/Principal Findings

We used mice heterozygous for a Dyrk1A targeted mutation (Dyrk1A+/−) to investigate the implication of this gene in the cognitive phenotypes of monosomy 21. Performance of Dyrk1A+/− mice was assayed 1/ in a navigational task using the standard hippocampally related version of the Morris water maze, 2/ in a swimming test designed to reveal potential kinesthetic and stress-related behavioral differences between control and heterozygous mice under two levels of aversiveness (25°C and 17°C) and 3/ in a long-term novel object recognition task, sensitive to hippocampal damage. Dyrk1A+/− mice showed impairment in the development of spatial learning strategies in a hippocampally-dependent memory task, they were impaired in their novel object recognition ability and were more sensitive to aversive conditions in the swimming test than euploid control animals.

Conclusions/Significance

The present results are clear examples where removal of a single gene has a profound effect on phenotype and indicate that haploinsufficiency of DYRK1A might contribute to an impairment of cognitive functions and stress coping behavior in human monosomy 21.     

A low frequency mosaicism for monosomy 21 in a live born female

Summary Monosomy 21, whether homogeneous or as a mosaicism, is very uncommon. We report here a 3-month-old white female with a low degree of monosomy 21 in the blood karyotype (6.5%, 110 cells counted) but not in the skin fibroblasts, which contained only the normal chromosome complement.The patient's physical features included microcephaly with frontal slanting; prominent occiput; ridge-shaped sutures; agenesis of the corpus callosum; large, prominent ears; high and narrow palate; micrognathia; tetralogy of Fallot; crowded toes; and dry, thick skin with very little subcutaneous tissue. The case is discussed in light of the suggested clinical features of the monosomy 21 syndrome and the possible implications of such a low-grade mosaicism in prenatal diagnosis.     

The gene coding for the α-chain of human propionyl-CoA carboxylase maps to chromosome band 13q32

Summary The human gene encoding the -polypeptide of propionyl-CoA carboxylase (PCC) has hitherto been localized to the distal half of the long arm of chromosome 13, segment 13q22q34. We studied the enzyme activities of mitochondrial carboxylases in cell cultures obtained from patients with different deletions of chromosome 13. By setting the PCC activity in normal diploid cell cultures (control group) at 100%, cell cultures with trisomy 13 showed 150% activity. In contrast, one of four patients with partial monosomy 13 had an enzyme activity of only 50%. Thus, by comparative deletion mapping, combined with studies of the gene-dosage effect, we have been able to assign the PCCA gene locus to chromosome band 13q32.     

Sur la localisation et la transmission d'une mutation chromosomique viable chez l'Amphibien urodèle: Pleurodeles waltlii Michah

A heterozygous reciprocal translocation between chromosomes 5 and 9 has been induced by rays in a fertilized egg of Pleurodeles waltlii. The resulting mutant female gave rise to offspring which, karyotypically, illustrated the six categories of gametes to be expected in the translocation heterozygote. Correspondence was established between these different chromosomal combinations and normal or anormal first generation phenotypes. Mutation T was linked to a partial monosomy (5)-trisomy (9). The structural analysis of the chromosomes at the somatic level led to the interpretation of the segments involved in the initial rearrangement. It consists of a reciprocal translocation probably accompanied by a pericentric inversion, without evident loss of genetic material.     

Cytogenetic studies of familial Prader-Willi syndrome

Summary A family in which two first cousins were found to have the Prader-Willi syndrome was investigated cytogenetically. Although G-banding analysis of metaphase chromosomes failed to demonstrate abnormality, close analyses on the fine prometaphase bands by G-banding and the DA-DAPI bands by double stainings revealed a distinct chromosome abnormality in this family. A reciprocal translocation, rep(14:15)(q11.2;q13), was detected in three family members: the mother, the maternal grandmother, and a maternal uncle of the proband. And, the proband and one of the first cousins had an unbalanced translocation that was derived from their carrier parents. The karyotypes of the affected cousins were determined as 46,XY or XX,-15,+der(14),rcp(14;15)(q11.2;q13). Therefore, they were considered to have an identical cytogenetic abnormality: a partial trisomy of the 14pterq11.2 segment and a partial monosomy of the 15pterq13 segment. Detailed clinical features of the proband and his affected cousin are described, main features associated with the Prader-Willi syndrome having been observed in both cousins. These observations support a definite relationship between the Prader-Willi syndrome and chromosome 15.     

Partial trisomy 17q and monosomy 9p due to a familial translocation.

Described is an infant with partial trisomy 17q and monosomy 9p [46,XX,-9,+der(9)t(9;17)(p21;q23)] due to adjacent-1 segregation of a maternal balanced reciprocal translocation. Characteristic clinical features of both partial 17q trisomy and monosomy 9p are present, but the former syndrome is less recognisable in this infant than in previously reported cases due to the concomitant 9p monosomy.     

Type and contretype signs in monosomy and trisomy 9p. On a case 46,XY, del (9) (pter yields p12:).

A 15-month-old male with a partial monosomy 9p is reported. The comparative analysis with other cases of 9p monosomy demonstrates a typical phenotype which when compared to that of 9p trisomy, permits the delineation of fifteen "type and contretype" signs.     

Cat-eye syndrome,a partial trisomy 22

Summary A family is presented in which a phenotypically normal mother and her healthy daughter both had abnormal children with a small supernumerary chromosome. Both had clinical symptoms suggestive of cat-eye syndrome. In both women 1 G-chromosome was found to be replaced by a small submetacentric satellited chromosome. Its fluorescence pattern was compatible with that of a chromosome 22, and so was the fluorescence pattern of the supernumerary chromosome in one of the phenotypically abnormal children. Since complete monosomy G in addition to partial autosomal trisomy would not be compatible with clinical normality the respective karyotypes must be interpreted as a small deletion of a chromosome 22 in the healthy mother and daughter and a partial trisomy 22 in their abnormal children. Therefore it can be concluded that a deletion of a chromosome 22 is compatible with a normal phenotype and that the cat-eye syndrome results, at least in this family, from a partial trisomy 22.

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Zusammenfassung Es wird über eine Familie berichtet, in der eine phänotypisch normale Mutter und ihre gesunde Tochter je ein abnormes Kind mit einem kleinen überzähligen Chromosom zur Welt gebracht hatten. Die Kinder hatten klinische Zeichen des Cat eye-Syndroms. Im Chromosomensatz beider Frauen war 1 G-Chromosom durch ein kleines submetazentrisches, satellitentragendes Chromosom ersetzt, dessen Fluorescenzumuster dem eines Chromosoms 22 entsprechen könnte. Das gleiche Muster wurde in dem überzähligen Chromosom bei einem der Kinder gefunden. Da eine totale G-Monosomie zusätzlich zu einer autosomalen Trisomie eines anderen Chromosoms nicht vereinbar ist mit vollkommener klinischer Unauffälligkeit, muß die Chromosomenanomalie der gesunden Mutter und Tochter als kleine Deletion 22 angesehen werden und die der abnormalen Kinder infolgedessen als partielle Trisomie 22. Aus diesen Befunden kann geschlossen werden, daß eine Deletion des Chromosoms 22 mit einem normalen Phänotyp vereinbar ist und daß, zumindest in dieser Familie, das Cat eye-Syndrom die Folge einer partiellen Trisomie 22 ist.

     

A female infant with monosomy 21

Summary A female infant with total monosomy 21 identified by Q banding is described. The main clinical features were hypertonia, prominent occiput, hypertelorism, antimongoloid slant of the eyes, broad nose, antimongoloid character of dermatoglyphics. Both parents are phenotypically as well as karyotypically normal.     

Chromosome 7 short arm deletion, 7p21→pter

Summary A case report of a de novo deletion in the short arm of chromosome 7 is presented (46,XX,del(7)(p21pter)). The five-month-old girl's major symptoms are: trigonocephalus with craniosynostosis, median bony forehead bulge, high palate, atrial septal defect, anal atresia and perineal fistula, thumb insertion far to ulnar-proximal, and a slightly retarded psychomotor development. The other cases with monosomy 7p described in the literature are reviewed.     

Reciprocal translocation between the proximal regions of the long arms of chromosomes 13 and 15 resulting in unbalanced offspring: characterization by fluorescence in situ hybridization and DNA analysis

Summary We describe two female siblings with similar clinical features consisting of hydrocephalus, scaphocephaly, hypotonia, mongoloid eye slant, blepharophimosis, micrognathia, supernumerary mouth frenula and mental retardation. Routine cytogenetic studies in the elder patient did not reveal any abnormality, and initially it was assumed that the syndrome had an autosomal recessive inheritance. However, a slightly larger chromosome 13 was seen in routine G-banded metaphases of the mother and the youngest of the two siblings. A shorter chromosome 15 was detected in the mother only. High resolution banding showed that the abnormal chromosome 13 contained an extra G-positive band at 13q12. The short chromosome 15 in the mother appeared to have a deletion of band q12. Fluorescence in situ hybridization using DNA markers specific to chromosomes 13 and 15 unequivocally showed that the mother was a carrier of a balanced reciprocal translocation t(13;15)(q12;q13), whereas the youngest sibling's karyotype was 46,XX,-13,+der(15)t(13;15)(q12;q13)mat, resulting in partial monosomy 13pterq12 and partial trisomy 15pterq13. The proband is thus trisomie for the critical region responsible for Prader-Willi syndrome and Angelman syndrome; this was confirmed by DNA analysis demonstrating one paternal and two maternal alleles from multiallelic marker loci mapping to 15q11-q13. This report illustrates the sensitivity and specificity offered by fluorescence in situ hybridization and its usefulness in the diagnosis and delineation of subtle chromosomal rearrangements.     

Clinical and Molecular Cytogenetic Analysis of a Rare Case of Mosaicism for Partial Trisomy 3p and Partial Trisomy 10q in Humans

The results of comprehensive clinical examination and molecular cytogenetic analysis of a patient carrying chromosome 3p+ in 69% of the peripheral blood lymphocytes are presented. Using microdissection of the metaphase chromosomes followed by DOP–PCR, a DNA library specific for the abnormal chromosome was obtained. By fluorescence in situ hybridization (FISH) of this DNA library on chromosomes from the patient and a healthy donor, the aberrant chromosome was identified as der(3)t(3;10)(p25;q24.3). Since this chromosome was present in only a proportion of patient's cells studied and no chromosome aberrations were revealed in cells of his parents, the der(3)t(3;10) is suggested to appear de novo. The cells carrying der(3)t(3;10) are monosomic for a proportion of 3p25 and trisomic for 10q24.3 qter. The developmental malformations revealed in the patient, such as the specific features of facial skeleton, mental retardation, microcephaly, and others are similar to those described previously in patients with partial 3p monosomy and 10q trisomy.     

Deoxyribonucleic acid damage study in primary amenorrhea by comet assay and karyotyping

AIM:

This study aims at evaluating the chromosomal abnormalities and deoxyribonucleic acid (DNA) damage in cases with primary amenorrhea by karyotyping and comet assay.

STUDY DESIGN:

A total of 30 cases of primary amenorrhea were recruited. Secondary sexual characters were assessed by Tanner staging. Chromosomal analysis was performed by conventional phytohemagglutinin stimulated lymphocyte cell culture technique. Alkaline version of comet assay was used to evaluate DNA damage.

RESULTS:

The chromosomal pattern of 20 subjects (66.7%) was found to be normal (46,XX). Two subjects had 46,XY pattern and eight subjects had Turner syndrome (45,X or 45,X/46,XX). The comet parameters were found to be increased among subjects with 45,X monosomy, when compared to the rest of the study group and also in subjects with Tanner stage 1 when compared to stage 2.

CONCLUSION:

Comet assay revealed increased DNA damage in cases with 45,X monosomy, compared with subjects with 46,XX and 46,XY karyotype, which correlated with clinical features.