Patau's syndrome and 13q21q translocation

Summary This paper reports the case of a one-day-old male child presenting the typical features of Patau's syndrome. The cytogenetic study by means of conventional techniques and GTG and QFQ banding techniques showed that the chromosomal pattern of the propositus was 46,XYq+,-21,+t(13q21q) 15ps+,22ps+, and that the nondisjunction that originated the translocation and trisomy had occurred in the mother.     

Sperm rates of 7q11.23, 15q11q13 and 22q11.2 deletions and duplications: a FISH approach

Genomic disorders are human diseases caused by meiotic chromosomal rearrangements of unstable regions flanked by Low Copy Repeats (LCRs). LCRs act as substrates for Non-Allelic Homologous Recombination (NAHR) leading to deletions and duplications. The aim of this study was to assess the basal frequency of deletions and duplications of the 7q11.23, 15q11-q13 and 22q11.2 regions in spermatozoa from control donors to check differences in the susceptibility to generate anomalies and to assess the contribution of intra- and inter-chromatid NAHR events. Semen samples from ten control donors were processed by FISH. A customized combination of probes was used to discriminate among normal, deleted and duplicated sperm genotypes. A minimum of 10,000 sperm were assessed per sample and region. There were no differences in the mean frequency of deletions and duplications (del + dup) among the 7q11.23, 15q11-q13 and 22q11.2 regions (frequency ± SEM, 0.37 ± 0.02; 0.46 ± 0.07 and 0.27 ± 0.07%, respectively) (P = 0.122). Nevertheless, hierarchical cluster analysis reveals interindividual differences suggesting that particular haplotypes could be the main source of variability in NAHR rates. The mean frequency of deletions was not different from the mean frequency of duplications in the 7q11.23 (P = 0.202) and 15q11-q13 (P = 0.609) regions, indicating a predominant inter-chromatid NAHR. By contrast, in the 22q11.2 region the frequency of deletions slightly exceed duplications (P = 0.032), although at the individual level any donor showed differences. Altogether, our results support the inter-chromatid NAHR as the predominant mechanism involved in the generation of sperm deletions and duplications.     

Colorectal cancer linkage on chromosomes 4q21, 8q13, 12q24, and 15q22

A substantial proportion of familial colorectal cancer (CRC) is not a consequence of known susceptibility loci, such as mismatch repair (MMR) genes, supporting the existence of additional loci. To identify novel CRC loci, we conducted a genome-wide linkage scan in 356 white families with no evidence of defective MMR (i.e., no loss of tumor expression of MMR proteins, no microsatellite instability (MSI)-high tumors, or no evidence of linkage to MMR genes). Families were ascertained via the Colon Cancer Family Registry multi-site NCI-supported consortium (Colon CFR), the City of Hope Comprehensive Cancer Center, and Memorial University of Newfoundland. A total of 1,612 individuals (average 5.0 per family including 2.2 affected) were genotyped using genome-wide single nucleotide polymorphism linkage arrays; parametric and non-parametric linkage analysis used MERLIN in a priori-defined family groups. Five lod scores greater than 3.0 were observed assuming heterogeneity. The greatest were among families with mean age of diagnosis less than 50 years at 4q21.1 (dominant HLOD?=?4.51, α?=?0.84, 145.40 cM, rs10518142) and among all families at 12q24.32 (dominant HLOD?=?3.60, α?=?0.48, 285.15 cM, rs952093). Among families with four or more affected individuals and among clinic-based families, a common peak was observed at 15q22.31 (101.40 cM, rs1477798; dominant HLOD?=?3.07, α?=?0.29; dominant HLOD?=?3.03, α?=?0.32, respectively). Analysis of families with only two affected individuals yielded a peak at 8q13.2 (recessive HLOD?=?3.02, α?=?0.51, 132.52 cM, rs1319036). These previously unreported linkage peaks demonstrate the continued utility of family-based data in complex traits and suggest that new CRC risk alleles remain to be elucidated.     

De novo 10q(q21q22) interstitial deletion

Summary We report a girl with a de novo interstitial deletion in the long arm of a chromosome 10. Clinical features are described.     

Exceptional complex chromosomal rearrangement and microdeletions at the 4q22.3q23 and 14q31.1q31.3 regions in a patient with azoospermia

In this report we describe the first patient ever found to have azoospermia in association with both exceptional complex chromosomal rearrangements and microdeletions at two translocation breakpoints. A 36-year-old male who had been suffering from male factor infertility was admitted to our clinic. The patient also displayed mild dysmorphia. An analysis of the patient's semen revealed azoospermia. GTG banding revealed the presence of an exceptional complex chromosomal rearrangement involving chromosomes 1, 4, 10 and 14. Using subtelomeric FISH analysis, the patient's karyotype was designated as 46,XY,t(1;10)(q43q44;q21q26.1)(CEB108/T7+,D1S3738-;10PTEL006+,D10S2290+, D1S3738+), ins(14;4) (q31.3;q23q33)(D14S1420+; D4S3359+, D4S2930+). Array-CGH analysis revealed two microdeletions at the 4q22.3q23 and 14q31.1q31.3 chromosomal regions. We suggest that microdeletions at the 4q22.3q23 and 14q31.1q31.3 chromosomal regions associated with both an exceptional complex chromosomal rearrangement and the Homo sapiens chromosome 4 open reading frame 37 (C4orf37) gene located at the 4q22.3q23 region might be associated with male factor infertility.     

Human homeo box-containing genes located at chromosome regions 2q31----2q37 and 12q12----12q13

Four human homeo box-containing cDNAs isolated from mRNA of an SV40-transformed human fibroblast cell line have been regionally localized on the human gene map. One cDNA clone, c10, was found to be nearly identical to the previously mapped Hox-2.1 gene at 17q21. A second cDNA clone, c1, which is 87% homologous to Hox-2.2 at the nucleotide level but is distinct from Hox-2.1 and Hox-2.2, also maps to this region of human chromosome 17 and is probably another member of the Hox-2 cluster of homeo box-containing genes. The third cDNA clone, c8, in which the homeo box is approximately 84% homologous to the mouse Hox-1.1 homeo box region on mouse chromosome 6, maps to chromosome region 12q12----12q13, a region that is involved in chromosome abnormalities in human seminomas and teratomas. The fourth cDNA clone, c13, whose homeo box is approximately 73% homologous to the Hox-2.2 homeo box sequence, is located at chromosome region 2q31----q37. The human homeo box-containing cluster of genes at chromosome region 17q21 is the human cognate of the mouse homeo box-containing gene cluster on mouse chromosome 11. Other mouse homeo box-containing genes of the Antennapedia class (class I) map to mouse chromosomes 6 (Hox-1, proximal to the IgK locus) and 15 (Hox-3). A mouse gene, En-1, with an engrailed-like homeo box (class II) and flanking region maps to mouse chromosome 1 (near the dominant hemimelia gene). Neither of the class I homeo box-containing genes--c8 and c13--maps to a region of obvious homology to chromosomal positions of the presently known mouse homeo box-containing genes.     

A jumping translocation (5p;15q), (8q;15q), and (12q;15q) (author's transl)]

Three balanced karyotypes (5p;15q), (8q;15q), and (12q;15q) were found simultaneously in a child with the Willi-Prader syndrome. The hypothesis is presented of a "jumping# translocation by affinity of telomeric and interstitial palindromes. The relationship between the Willi-Prader syndrome and a juxtacentric anomaly of the long arm of chromosome 15 is discussed.     

Translocation (13q21q)

Summary A (13q21q) translocation was found in an infant with Down's syndrome. The 17-year-old mother and the grandmother carried the translocation 45,XX,t(13;21)(p12;q11). The great grandparents had normal karyotypes. Fluorescence marker studies suggested that the translocation originated in the great grandmother. The hypothesis was supported by satellite association studies which showed a significant excess of 13–21 and 13–15 associations in the great grandmother.     

Chromosomal region 13q21q31 and heterochrony of development

If the theory of evolution is now largely accepted, there are still many debates on the mechanisms of evolution, including human evolution. One of these mechanisms is heterochrony of development including progenesis and neoteny. We report on a patient who could be an example of human progenesis. This boy was born prematurely, after a cesarian section for preeclampsia. Family history was unremarkable. He walked unaided when he was 2.5 years old. At 5 years of age height was 95 cm (< 3rd centile), weight 18.6 kg (40th centile) and OFC 54 cm (98th centile is 53 cm). He had a macropenis. He attended elementary school. However, at 9 years of age he had to have special education. Puberty occurred when he was 8 years old. At 14 years of age height was 141 cm (3rd centile is 144 cm), weight 32.5 kg (3rd centile) and OFC 55.5 cm (75th centile). At physical examination he had hypertelorism, narrow forehead, short philtrum, retromicrognathia, large and low set ears, hyperlaxity, overcrowed teeth, dorsal kyphosis, and macropenis. Karyotype showed a deletion 13q21q31. The deletion was de novo and pure. In conclusion this case with sexual precocity and small final stature could be an example of progenesis, rising the question of the presence of a critical region for human evolution within chromosomal region 13q21q31.     

Homologous Robertsonian translocation (21q21q) and abortions

Summary Instances of balanced Robertsonian translocations between the homologues of chromosome 21 were observed in two couples with a history of repeated abortions. The male partner of one couple and the female partner of another couple exhibited this anomaly. The translocation (21q21q) was found to be transmitted to their live children with Down's syndrome.     

Partial trisomy 14q and familial translocation (2;14) (q12;q13).

A female patient with moderate psychomotor retardation, minor anomalies and proximal trisomy 14q due to segregation of a maternal translocation is reported.     

Familial paracentric inversions inv(2)(q31q35) and inv(8)(q22.3q24.13) ascertained through reproductive abnormalities

Summary Two cases of familial paracentric inversion, one in the long arm of chromosome 2 and the other in the long arm of chromosome 8, are described. The first was ascertained in a woman who was studied because of recurrent abortions. The second was ascertained in the father of a girl with the trichorhinophalangeal syndrome and an interstitial deletion in 8q. The latter is the first case in which unequal crossing over in an inversion loop can be inferred in a male carrier of a paracentric inversion. The reasons for the relatively low frequency of paracentric inversions observed and factors which affect the pregnancy outcome are discussed.     

Precocious puberty associated with partial trisomy 18q and monosomy 11q

We report a 10-years-old female patient with a partial trisomy 18q and monosomy 11q due to a maternal translocation. The phenotype of our proband is partially common with Jacobsen syndrome and duplication 18q but she has also some atypical anomalies such as precocious puberty, a retinal albinism and hypermetropia. Based on cytogenetics and FISH analysis, the karyotype of the proband was 46,XX,der(11)t(11;18)(q24;q13). To the best of our knowledge, this is the first report of precocious puberty associated with either dup(18q) or del(11q) syndromes.     

Partial trisomy 2q and familial translocation t(2;12)(q31;q24)

Summary Report is given of a boy with trisomy of the distal part of the long arm of chromosome 2 (q31ter) due to a balanced 2/12 translocation in the mother: 46,XX,t(2;12) (q31;q24). Other phenotypically normal carriers of this balanced translocation are the patients sister and grandfather. The patient shows a variety of dysplastic signs mainly of the face.     

Four novel Loci (19q13, 6q24, 12q24, and 5q14) influence the microcirculation in vivo

There is increasing evidence that the microcirculation plays an important role in the pathogenesis of cardiovascular diseases. Changes in retinal vascular caliber reflect early microvascular disease and predict incident cardiovascular events. We performed a genome-wide association study to identify genetic variants associated with retinal vascular caliber. We analyzed data from four population-based discovery cohorts with 15,358 unrelated Caucasian individuals, who are members of the Cohort for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium, and replicated findings in four independent Caucasian cohorts (n = 6,652). All participants had retinal photography and retinal arteriolar and venular caliber measured from computer software. In the discovery cohorts, 179 single nucleotide polymorphisms (SNP) spread across five loci were significantly associated (p<5.0×10(-8)) with retinal venular caliber, but none showed association with arteriolar caliber. Collectively, these five loci explain 1.0%-3.2% of the variation in retinal venular caliber. Four out of these five loci were confirmed in independent replication samples. In the combined analyses, the top SNPs at each locus were: rs2287921 (19q13; p = 1.61×10(-25), within the RASIP1 locus), rs225717 (6q24; p?=?1.25×10(-16), adjacent to the VTA1 and NMBR loci), rs10774625 (12q24; p = 2.15×10(-13), in the region of ATXN2,SH2B3 and PTPN11 loci), and rs17421627 (5q14; p?=?7.32×10(-16), adjacent to the MEF2C locus). In two independent samples, locus 12q24 was also associated with coronary heart disease and hypertension. Our population-based genome-wide association study demonstrates four novel loci associated with retinal venular caliber, an endophenotype of the microcirculation associated with clinical cardiovascular disease. These data provide further insights into the contribution and biological mechanisms of microcirculatory changes that underlie cardiovascular disease.     

Siblings with opposite chromosome constitutions,dup(2q)/del(7q) and del(2q)/dup(7q)

Chromosome 7q36 microdeletion syndrome is a rare genomic disorder characterized by underdevelopment of the brain, microcephaly, anomalies of the sex organs, and language problems. Developmental delay, intellectual disability, autistic spectrum disorders, BDMR syndrome, and unusual facial morphology are the key features of the chromosome 2q37 microdeletion syndrome. A genetic screening for two brothers with global developmental delay using high-resolution chromosomal analysis and subtelomeric multiplex ligation-dependent probe amplification revealed subtelomeric rearrangements on the same sites of 2q37.2 and 7q35, with reversed deletion and duplication. Both of them showed dysmorphic facial features, severe disability of physical and intellectual development, and abnormal genitalia with differential abnormalities in their phenotypes. The family did not have abnormal genetic phenotypes. According to the genetic analysis of their parents, adjacent-1 segregation from their mother's was suggested as a mechanism of their gene mutation. By comparing the phenotypes of our patients with previous reports on similar patients, we tried to obtain the information of related genes and their chromosomal locations.     

Isochromosome not translocation in trisomy 21q21q

Summary After primary trisomy, de novo 21q21q trisomy is the most frequent chromosomal aberration responsible for Down syndrome. This rearrangement is more commonly referred to as a Robertsonian translocation or centric fusion product than as an isochromosome, e.g., t(21q;21q) instead of i(21q); however, in practice, it has not so far proved possible to distinguish between these alternatives. The aim of this work was to establish which of the two alternatives is acceptable.     

Inv21p12q22del21q22 and intellectual disability

Chromosomal rearrangements are common in humans. Pericentric inversions are among the most frequent aberrations (1–2%). Most inversions are balanced and do not cause problems in carriers unless one of the breakpoints disrupts important functional genes, has near submicroscopic copy number variants or hosts “cryptic” complex chromosomal rearrangements. Pericentric inversions can lead to imbalance in offspring. Less than 3% of Down syndrome patients have duplication as a result of parental pericentric inversion of chromosome 21. We report a family with an apparently balanced pericentric inversion of chromosome 21. The proband, a 23-year-old female was referred for prenatal diagnosis at 16 weeks gestation because of increased nuchal translucency. She has a familial history of Down's syndrome and moderate intellectual disability, a personal history of four spontaneous abortions and learning difficulties. Peripheral blood and amniotic fluid samples were collected to perform proband's and fetus' cytogenetic analyses. Additionally, another six family members were evaluated and cytogenetic analysis was performed. Complementary FISH and MLPA studies were carried out. An apparent balanced chromosome 21 pericentric inversion was observed in four family members, two revealed a recombinant chromosome 21 with partial trisomy, and one a full trisomy 21 with an inverted chromosome 21. Array CGH analysis was performed in the mother and the brother's proband. MLPA and aCGH studies identified a deletion of about 1.7 Mb on the long arm of inverted chromosome 21q22.11. We believe the cause of the intellectual disability/learning difficulties observed in the members with the inversion is related to this deletion. The recombinant chromosome 21 has a partial trisomy including the DSCR with no deletion. The risk for carriers of having a child with multiple malformations/intellectual disability is about 30% depending on whether and how this rearrangement interferes with meiosis.