The 11q;22q translocation: a collaborative study of 20 new cases and analysis of 110 families

Emanuel syndrome and congenital diaphragmatic hernia: A systematic review

BACKGROUND

Emanuel Syndrome (ES), a rare chromosomal disorder caused by a supernumerary chromosome 22 derivative (der(22)t(11;22)), was identified in a fetus with congenital diaphragmatic hernia (CDH) at our fetal center. We aimed to identify a precedent for clinical care and patient outcomes to guide family decision-making.

METHODS

This non-funded and non-registered study queried the entire CDH Registry (CDHR) including >10,000 patients since 1995 and conducted a systematic literature review for patients with concomitant ES and CDH.

RESULTS

Literature review captured 12 citations and identified 9 patients with CDH+ES from over 400 known ES cases. Given the rarity of the disease and to reduce bias, there were no exclusion criteria aside from non-English language. Of these 9, two underwent surgical CDH repair with neither surviving. The CDHR identified 6 patients with ES, all reported after 2013 and prenatally diagnosed. Median estimated gestational age was 39 weeks (range 37-40) and median birth weight was 2.72 kg (range 2.4-3.4 kg). 3 patients died within the first few postnatal days; surgical repair was not offered due to "anomalies" and "pulmonary hypertension" in two and one family chose comfort measures. The other 3 patients underwent surgical repair, and 2 were supported with ECMO. Two patients survived to discharge, incurring surgical comorbidities associated with severe CDH including gastrostomy dependence, tracheostomy, and CDH recurrence.

CONCLUSIONS

ES patients with CDH have potential to tolerate repair and survive to discharge, however with significant additional morbidity combined with severe challenges inherent to ES. This represents the largest series of patients with CDH and ES to date.

LEVEL OF EVIDENCE

IV (Case series with no comparison group).

Criteria to evaluate patterns of segmental and complete aneuploidies in preimplantation genetic testing for aneuploidy results suggestive of an inherited balanced translocation or inversion

Objective

To define criteria for determining when preimplantation genetic testing for aneuploidy (PGT-A) results are suggestive of a potential balanced chromosomal rearrangement in the egg or sperm source and warrant karyotyping.

Design

Performance evaluation of criteria developed to assess PGT-A results for patterns of imbalances suggestive of a balanced chromosomal rearrangement in the egg or sperm source.

Setting

A single PGT-A laboratory and multiple in vitro fertilization centers.

Patients

Reproductive couples who underwent routine PGT-A testing.

Interventions

Karyotyping of reproductive couples for whom patterns of imbalances observed in PGT-A results suggested a balanced chromosomal rearrangement in the egg or sperm source.

Main Outcome Measures

Correct or incorrect flagging of predicted translocation in either the egg or sperm source based on chromosome analysis.

Results

Proposed criteria correctly predicted a balanced reciprocal translocation in 97% of cases (n = 33), a (13;14) Robertsonian translocation in all cases (n = 3), and an inversion in all cases (n = 2). Other criteria evaluated were determined to be ineffective because of relatively low occurrences that met the criteria and/or low predictive value.

Conclusions

Our results showed that the proposed criteria were effective for evaluating patterns of imbalances observed in PGT-A results suggestive of a potential chromosomal rearrangement in the egg or sperm source. Our proposed criteria can be employed by clinicians in the in vitro fertilization setting in combination with a patient's reproductive history to identify PGT-A patients who are likely carriers of balanced chromosomal rearrangements.

Inheritance of imbalances in recurrent chromosomal translocation t(11;22): clarification by PGT-SR and sperm-FISH analysis

RESEARCH QUESTION

To analyse why unbalanced viable offspring are derived mainly from the 3:1 segregation mode in t(11;22)(q23;q11.2) reciprocal translocation.

DESIGN

Retrospective analysis of 24 pre-implantation genetic testing for chromosomal structural re-arrangements (PGT-SR) cycles was performed on seven male and five female carriers of t(11;22) translocation. Sperm analysis was performed on each male carrier. These patients were directed to the study centre after several years of miscarriages and/or abortions, primary infertility for male carriers or birth of an affected child.

RESULTS

Twenty-four PGT-SR cycles were performed to exclude imbalances in both male and female carriers. The unbalanced embryos derived from the adjacent-1 segregation mode were the most represented in both male and female carriers (68.4% and 50%, respectively). These results were positively related with meiotic segregation analysis of reciprocal translocation in spermatozoa. A thorough analysis of the unbalanced embryo karyotypes determined that the expected viable +der22 karyotype resulting from 3:1 malsegregation was less represented at 5.3%.

CONCLUSIONS

These findings highlight the divergence that may exist between meiotic segregation and post-zygotic selection. Post-zygotic selection would be responsible for the elimination of unbalanced embryos derived from the adjacent-1 segregation mode. The combined action of several factors occurs at the beginning of post-zygotic selection. Genetic counselling must consider the risk of a birth related to the adjacent-1 segregation mode, irrespective of the sex of the translocation carrier. These results will allow deeper understanding of the PGT results of t(11;22) carriers, which often include a high number of aneuploid embryos.

The Frequency and Spectrum of Chromosomal Translocations in a Cohort of Sri Lankans

Translocations are the most common type of structural chromosomal abnormalities. Unbalanced translocations are usually found in children who present with congenital abnormalities, developmental delay, or intellectual disability. Balanced translocations are usually found in adults who frequently present with reproductive failure; either subfertility, or recurrent pregnancy loss. Herein, we report the spectrum and frequency of translocations in a Sri Lankan cohort. A database of patients undergoing cytogenetic testing was maintained prospectively from January 2007 to December 2016 and analyzed, retrospectively. A total of 15,864 individuals were tested. Among them, 277 (1.7%) had translocations. There were 142 (51.3%) unbalanced translocations and 135 (48.7%) balanced translocations. Majority (160; 57.8%) were Robertsonian translocations. There were 145 (52.3%) children and adolescents aged less than 18 years with translocations, and 142 (97.9%) were unbalanced translocations. Majority [138 (95.2%)] were referred due to congenital abnormalities, developmental delay, or intellectual disability, and 91 were children with translocation Down syndrome. All adults aged 18 years or above (132) had balanced translocations. Subfertility and recurrent pregnancy loss [84 (63.6%)] and offspring(s) with congenital abnormalities [48 (36.4%)] were the most common indications in this group. Majority (68.2%) in this group were females with reciprocal translocations (55.3%). Chromosomes 21, 14, and 13 were the most commonly involved with rob(14q21q) [72 (26%)], rob(21q21q) [30 (13.7%)], and rob(13q14q) [34 (12.3%)] accounting for 52% of the translocations. Chromosomes 1, 8, 11, and 18 were most commonly involved in reciprocal translocations. The observed high frequency of chromosomal translocations in our cohort highlights the importance of undertaking cytogenetic evaluation and providing appropriate genetic counseling for individuals with the phenotypes associated with these translocations.

Ocular manifestations of Emanuel syndrome

Emanuel syndrome is caused by a supernumerary der(22)t(11;22) and typically manifests with intellectual disability and craniofacial dysmorphism. Ocular abnormalities have infrequently been described. We report a 36-year-old man with severe intellectual disability, aphasia, and facial dysmorphism, with high myopia and juvenile open angle glaucoma (JOAG). Microarray analysis results included 47,XY,+der(22)t(11;22)(q23;q11.2), and a 269 kb deletion of 7q31.33(125,898,014-126,166,829). Two candidate genes were identified as possible etiologies for the ocular pathologies in our patient: a MFRP duplication on chromosome 11, which may play a role in high myopia and dysregulation of emmetropization, and a GRM8 deletion on chromosome 7, which may cause glutamate-induced excitotoxicity and therefore have a role in the development of JOAG, unrelated to the Emanuel syndrome genotype. We provide the first detailed description these ocular abnormalities in a patient with Emmanuel syndrome.

Ultrasound, Echocardiography, MRI, and Genetic Analysis of a Fetus with Congenital Diaphragmatic Hernia and Partial 11q Trisomy

Congenital diaphragmatic hernia (CDH) is a serious birth defect with a significant mortality and morbidity. The current and constant progress in ultrasound techniques has led to the improvement of the prenatal diagnosis of this malformation. CDH is a developmental defect whose etiology is heterogeneous and takes place when the pleuroperitoneal folds and septum transversum fail to converge and fuse. Survival depends on the extent of pulmonary hypoplasia and the disease may be potentially worsened by the presence of added congenital defects. 40% of CDH cases are associated with at least one additional anomaly. The ultrasound diagnosis is established with essential signs: loss of uniform echogenicity of lungs and marked mediastinal shift. We report the case of a fetus with isolated CDH diagnosed at 21 weeks of gestation by ultrasound and confirmed by RMI, whose genetic analysis of amniotic fluid cells identified a de novo partial trisomy of the long arm of chromosome 11. Different genetic causes have been associated with CDH. Moreover, it is expectable that the use of new techniques for prenatal diagnosis will reveal novel CNVs associated with CDH and will help us to estimate the recurrence risk for this defect as well as for other associated anomalies.

A clinical and molecular analysis of a patient with Emanuel syndrome

Emanuel syndrome (ES) is the most frequent type of recurrent non‑Robertsonian translocation that is characterized by numerous anomalies. Over 100 patients with ES have been described in the literature. The phenotype of this syndrome varies but often consists of facial dysmorphism, microcephaly, severe intellectual disability, developmental retardation, congenital heart disease and genital anomalies. The present study describes a 2‑year‑old boy with multiple malformations, including facial dysmorphism, severe intellectual disability, growth retardation, congenital heart disease, cleft lip and palate, genital malformation (micropenis), amblyopia, thymic dysplasia and hearing impairment. The karyotype of the patient was 47,XY,+del(22)(q13), and the maternal karyotype was 46,XX,t(11;22)(q25;q13),9qh‑,15p+. Single‑nucleotide polymorphism‑array analysis of the proband indicated a partial duplication of chromosomes 22 and 11 at 22q11.1‑q11.21 and 11q23.3‑q25, respectively, which confirmed the diagnosis of ES. To date, no cases of ES have been reported in mainland China. The present case further emphasizes the necessity and importance of high‑resolution techniques for genetic diagnosis and for subsequent genetic counseling. The present study contributed to the phenotypic delineation of ES and confirmed the first ES patient in mainland China.

Genetic causes of congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a moderately prevalent birth defect that, despite advances in neonatal care, is still a significant cause of infant death, and surviving patients have significant morbidity. The goal of ongoing research to elucidate the genetic causes of CDH is to develop better treatment and ultimately prevention. CDH is a complex developmental defect that is etiologically heterogeneous. This review summarizes the recurrent genetic causes of CDH including aneuploidies, chromosome copy number variants, and single gene mutations. It also discusses strategies for genetic evaluation and genetic counseling in an era of rapidly evolving technologies in clinical genetic diagnostics.

Human embryonic stem cells carrying an unbalanced translocation demonstrate impaired differentiation into trophoblasts: an in vitro model of human implantation failure

Carriers of the balanced translocation t(11;22), the most common reciprocal translocation in humans, are at high risk of creating gametes with unbalanced translocation, leading to repeated miscarriages. Current research models for studying translocated embryos and the biological basis for their implantation failure are limited. The aim of this study was to elucidate whether human embryonic stem cells (hESCs) carrying the unbalanced chromosomal translocation t(11;22) can provide an explanation for repeated miscarriages of unbalanced translocated embryos. Fluorescent in situ hybridization and karyotype analysis were performed to analyze the t(11;22) in embryos during PGD and in the derived hESC line. The hESC line was characterized by RT-PCR and FACS analysis for pluripotent markers. Directed differentiation to trophoblasts was carried out by bone morphogenetic protein 4 (BMP4). Trophoblast development was analyzed by measuring β-hCG secretion, by β-hCG immunostaining and by gene expression of trophoblastic markers. We derived the first hESC line carrying unbalanced t(11;22), which showed the typical morphological and molecular characteristics of a hESC line. Control hESCs differentiated into trophoblasts secreted increasing levels of β-hCG and concomitantly expressed the trophoblast genes, CDX2, TP63, KRT7, ERVW1, CGA, GCM1, KLF4 and PPARG. In contrast, differentiated translocated hESCs displayed reduced and delayed secretion of β-hCG concomitant with impaired expression of the trophoblastic genes. The reduced activation of trophoblastic genes may be responsible for the impaired trophoblastic differentiation in t(11;22)-hESCs, associated with implantation failure in unbalanced t(11;22) embryos. Our t(11;22) hESCs are presented as a valuable human model for studying the mechanisms underlying implantation failure.

Phenotype and micro-array characterization of duplication 11q22.1-q25 and review of the literature

Partial duplication of 11q is related to several malformations like growth retardation, intellectual disability, hypoplasia of corpus callosum, short nose, palate defects, cardiac, urinary tract abnormalities and neural tube defects. We have studied the clinical and molecular characteristics of a patient with severe intellectual disabilities, dysmorphic features, congenital inguinal hernia and congenital cerebral malformation which is referred to as cytogenetic exploration. We have used FISH and array CGH analysis for a better understanding of the double chromosomic aberration involving a 7p microdeletion along with a partial duplication of 11q due to adjacent segregation of a paternal reciprocal translocation t(7;11)(p22;q21) revealed after banding analysis. The patient's karyotype formula was: 46,XY,der(7)t(7;11)(p22;q21)pat. FISH study confirmed these rearrangement and array CGH technique showed precisely the loss of at least 140 Kb on chromosome7p22.3pter and 33.4Mb on chromosome11q22.1q25. Dysmorphic features, severe intellectual disability and brain malformations could result from the 11q22.1q25 trisomy. Our study provides an additional case for better understanding and delineating the partial duplication 11q.

Renal cell carcinoma and a constitutional t(11;22)(q23;q11.2): case report and review of the potential link between the constitutional t(11;22) and cancer

We observed a t(11;22)(q23-24;q11.2-12) and monosomy 3 in renal tumor cells from a 72-year-old man. The hypothesis of a primitive peripheral neuroectodermal tumor (PPNET) located in the kidney was promptly excluded: Histologically, the tumor was a clear cell renal cell carcinoma (RCC) and we did not observe an EWSR1 gene rearrangement. The constitutional origin of this alteration was established. We report on the second case of RCC in a patient with a constitutional t(11;22). The t(11;22)(q23;q11.2) is the main recurrent germline translocation in humans. Unbalanced translocation can be transmitted to the progeny and can cause Emanuel syndrome. Our observation alerts cancer cytogeneticists to the fortuitous discovery of the constitutional t(11;22) in tumor cells. This translocation appears grossly similar to the t(11;22)(q24;q12) of PPNET and should be evoked if present in all cells of a tumor other than PPNET. This is important when providing appropriate genetic counseling. Moreover, the potential oncogenic role of the t(11;22) and its predisposing risk of cancer are under debate. The family history of the patient revealed a disabled brother who died at an early age from colon cancer and a sister with breast cancer. This observation reopens the issue of a link between the constitutional t(11;22) and cancer, and the utility of cancer prevention workups for t(11;22) carriers.

Chromosome analysis using spectral karyotyping (SKY)

Spectral karyotyping is a novel technique for chromosome analysis that has been developed based on the approach of the fluorescence in situ hybridization technique. Spectral karyotyping makes it feasible to diagnose a variety of diseases, because of its technology in painting each of the 24 human chromosomes with different colors. In recent years, it has become possible to adopt the usage of spectral karyotyping for research in general clinical practice, and its usability has attracted particular attention in the diagnosis of different diseases. In this review, we will explain the principle of the spectral karyotyping, as well as its specificity and limitation in detecting the genetic defects within clinical application by presenting two case reports.

Unexpected results in the constitution of small supernumerary marker chromosomes

Traditional approaches for the classification of Small Supernumerary Marker Chromosomes (sSMC), mostly based on FISH techniques, are time-consuming and not always sufficient to fully understand the true complexity of this class of rearrangements. We describe four supernumerary marker chromosomes that, after array-CGH, were interpreted rather differently in respect to the early classification made by conventional cytogenetics and FISH investigations, reporting two types of complex markers which DNA content was overlooked by conventional approaches: 1. the sSMC contains non-contiguous regions of the same chromosome and, 2. the sSMC, initially interpreted as a supernumerary del(15), turns out to be a derivative 15 to which the portion of another chromosome was attached. All are likely derived from partial trisomy rescue events, bringing further demonstration that germline chromosomal imbalances are submitted to intense reshuffling during the embryogenesis, leading to unexpected complexity and changing the present ideas on the composition of supernumerary marker chromosomes.

Preimplantation genetic diagnosis in female and male carriers of reciprocal translocations: clinical outcome until delivery of 312 cycles

Carriers of reciprocal translocations (rcp) are known to be at risk for reproductive difficulties. Preimplantation genetic diagnosis (PGD) is one of the options these carriers have to try in order to fulfil their desire to have a child. In the present study, we retrospectively looked at the results of 11 years (1997-2007) of PGD for rcp in our center to improve the reproductive counseling of these carriers. During this period 312 cycles were performed for 69 male and 73 female carriers. The mean female age was 32.8 years, the mean male age 35.8 years. Most carriers were diagnosed with a translocation because of fertility problems or recurrent miscarriages, and most of them opted for PGD to avoid these problems. In 150 of the 312 cycles, embryo transfer (ET) was feasible and 40 women had a successful singleton or twin pregnancy. This gives a live birth delivery rate of 12.8% per started cycle and of 26.7% per cycle with ET. Owing to the large number of abnormal embryos, PGD cycles for rcp often lead to cancellation of ET, explaining the low success rate when expressed per cycle with oocyte pick-up. Once ET was feasible, the live birth delivery rate was similar to that of PGD in general at our center. PGD is therefore an established option for specific reciprocal translocation carriers.

A 54 Mb 11qter duplication and 0.9 Mb 1q44 deletion in a child with laryngomalacia and agenesis of corpus callosum

BACKGROUND

Partial Trisomy 11q syndrome (or Duplication 11q) has defined clinical features and is documented as a rare syndrome by National Organization of Rare Disorders (NORD). Deletion 1q44 (or Monosomy 1q44) is a well-defined syndrome, but there is controversy about the genes lying in 1q44 region, responsible for agenesis of the corpus callosum. We report a female child with the rare Partial Trisomy 11q syndrome and Deletion 1q44 syndrome. The genomic imbalance in the proband was used for molecular characterization of the critical genes in 1q44 region for agenesis of corpus callosum. Some genes in 11q14q25 may be responsible for laryngomalacia.

RESULTS

We report a female child with dysmorphic features, microcephaly, growth retardation, seizures, acyanotic heart disease, and hand and foot deformities. She had agenesis of corpus callosum, laryngomalacia, anterior ectopic anus, esophageal reflux and respiratory distress. Chromosome analysis revealed a derivative chromosome 1. Her karyotype was 46,XX,der(1)t(1;11)(q44;q14)pat. The mother had a normal karyotype and the karyotype of the father was 46,XY,t(1;11)(q44;q14). SNP array analysis showed that the proband had a 54 Mb duplication of 11q14q25 and a 0.9 Mb deletion of the submicroscopic subtelomeric 1q44 region. Fluorescence Insitu Hybridisation confirmed the duplication of 11qter and deletion of 1qter.

CONCLUSION

Laryngomalacia or obstruction of the upper airway is the outcome of increased dosage of some genes due to Partial Trisomy 11q Syndrome. In association with other phenotypic features, agenesis of corpus callosum appears to be a landmark phenotype for Deletion 1q44 syndrome, the critical genes lying proximal to SMYD3 in 1q44 region.

Variabilidade fenotípica na síndrome do cromossomo supernumerário der(22)t(11;22) (síndrome de Emanuel)

OBJETIVO: Relatar dois pacientes com a síndrome de Emanuel (SE) ou cromossomo supernumerário der(22)t(11;22), secundária a translocações balanceadas familiares, apresentando fenótipos distintos. DESCRIÇÃO DE CASO: O primeiro paciente é uma menina branca de cinco anos de idade, apresentando hipotonia, atraso no desenvolvimento neuropsicomotor, movimentos estereotipados, microcefalia, ptose palpebral, orelhas proeminentes, fossetas e apêndices pré-auriculares, e imperfuração anal. As avaliações adicionais identificaram hipoplasia cerebral e estenose da válvula pulmonar. Possuía história também de laringotraqueomalácia e fenda palatina. O segundo paciente é um menino branco de seis meses de idade com hipotonia, movimentos coreoatetóticos, déficit de crescimento, microcefalia, microssomia hemifacial, fenda palatina, microtia, apêndices pré-auriculares e polegares proximalmente implantados. A ecocardiografia demonstrou estenose da válvula pulmonar, comunicação interatrial e interventricular, persistência do canal arterial e da veia cava superior esquerda. A radiografia de tórax identificou uma costela cervical. O cariótipo por bandas GTG mostrou a presença, em ambos os pacientes, de um cromossomo adicional der(22)t(11;22), secundário a uma translocação balanceada materna no primeiro caso e paterna no segundo caso. COMENTÁRIOS: Apesar de a primeira paciente apresentar achados frequentes da SE, o caso adicional representa a segunda descrição da literatura com um fenótipo de espectro óculo-aurículo-vertebral (EOAV). Assim, ambos salientam a variabilidade clínica observada na SE e a importância da avaliação cariotípica em indivíduos com fenótipo de EOAV.

Phenotypic delineation of Emanuel syndrome (supernumerary derivative 22 syndrome): Clinical features of 63 individuals

Emanuel syndrome is characterized by multiple congenital anomalies and developmental disability. It is caused by the presence of a supernumerary derivative chromosome that contains material from chromosomes 11 and 22. The origin of this imbalance is 3:1 malsegregation of a parental balanced translocation between chromosomes 11 and 22, which is the most common recurrent reciprocal translocation in humans. Little has been published on the clinical features of this syndrome since the 1980s and information on natural history is limited. We designed a questionnaire to collect information from families recruited through an international online support group, Chromosome 22 Central. Data gathered include information on congenital anomalies, medical and surgical history, developmental and behavioral issues, and current abilities. We received information on 63 individuals with Emanuel syndrome, ranging in age from newborn to adulthood. As previously recognized, congenital anomalies were common, the most frequent being ear pits (76%), micrognathia (60%), heart malformations (57%), and cleft palate (54%). Our data suggest that vision and hearing impairment, seizures, failure to thrive and recurrent infections, particularly otitis media, are common in this syndrome. Psychomotor development is uniformly delayed, however the majority of individuals (over 70%) eventually learn to walk with support. Language development and ability for self-care are also very impaired. This study provides new information on the clinical spectrum and natural history of Emanuel syndrome for families and physicians caring for these individuals.

Regional expression of dopamine D1 and D2 receptor proteins in the cerebral cortex of asphyxic newborn infants

Dopamine D(1) and D(2) receptor protein expression was examined by Western blotting in newborn infants dying from cerebral asphyxia between 31 and 42 weeks' gestation, and matched controls. Frontal, occipital, temporal, and motor cortex tissue samples were obtained at autopsy (median postmortem interval 35 hours) and frozen for storage at -80 degrees C. A total of 2 immunoreactive bands were detected with each primary antibody in infant brain, whereas a single band was present in adult human and rat tissue. Immunoreactivity varied between cortical areas for both receptors, but their regional patterns differed significantly. D(1) protein levels were higher in motor and temporal cortex than in frontal or occipital cortex. D(2) protein showed graded expression frontal > motor > occipital > temporal cortex. Asphyxia cases showed lower expression of the upper D(2) immunoreactive band, but no difference in regional pattern. Lower D(2) receptor expression may attenuate stress responses and underlie increased vulnerability to hypoxia at birth.

Molecular mechanisms and diagnosis of chromosome 22q11.2 rearrangements

Several recurrent, constitutional genomic disorders are present on chromosome 22q. These include the translocations and deletions associated with DiGeorge and velocardiofacial syndrome and the translocations that give rise to the recurrent t(11;22) supernumerary der(22) syndrome (Emanuel syndrome). The rearrangement breakpoints on 22q cluster around the chromosome-specific segmental duplications of proximal 22q11, which are involved in the etiology of these disorders. While the deletions are the result of nonallelic homologous recombination (NAHR) between low copy repeats or segmental duplications within 22q11, the t(11;22) is the result of rearrangement between palindromic AT-rich repeats on 11q and 22q. Here we describe the mechanisms responsible for these recurrent rearrangements, discuss the recurrent deletion endpoints that are the result of NAHR between chromosome 22q specific low copy repeats as well as present current diagnostic approaches to deletion detection.

Genetic factors in congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a relatively common birth defect associated with high mortality and morbidity. Although the exact etiology of most cases of CDH remains unknown, there is a growing body of evidence that genetic factors play an important role in the development of CDH. In this review, we examine key findings that are likely to form the basis for future research in this field. Specific topics include a short overview of normal and abnormal diaphragm development, a discussion of syndromic forms of CDH, a detailed review of chromosomal regions recurrently altered in CDH, a description of the retinoid hypothesis of CDH, and evidence of the roles of specific genes in the development of CDH.

Meiotic segregation analysis in male translocation carriers by using fluorescent in situ hybridization

Balanced reciprocal and Robertsonian translocations are the most common structural chromosome abnormalities in humans, with incidences of 0.7 and 1.23 per 1000. These translocations can affect fertility and/or pregnancy outcome because of possibly impaired production of gametes with an unbalanced zygote caused by the parental arrangement. Fertility problems in male translocation carriers are because of various degrees of sperm alterations that are directly related to the disturbance of the meiotic process. Investigation of human sperm chromosomes was performed by karyotyping spermatozoa after penetration of zona-free hamster oocytes, karyotype analysis now being possible to analyse the segregation patterns by using fluorescent in situ hybridization (FISH). Here, we document the results of meiotic segregation analysis for four Robertsonian and four reciprocal translocation carriers by FISH. In the sperm of Robertsonian translocation males, the majority of spermatozoa were normal/balanced. On the other hand, males with reciprocal translocations demonstrated a high rate of unbalanced spermatozoa of about 50% on meiotic segregation, with an unusually high rate (23.5%) of 3 : 1 segregation. This knowledge can be used for genetic counselling of families with these types of translocations.

High incidence of familial breast cancer segregates with constitutional t(11;22)(q23;q11)

In a family with a high incidence of postmenopausal breast cancer and a case of glioblastoma, the constitutional translocation t(11;22)(q23;q11.2) was shown to segregate with the malignancies. The breakpoints in this family coincided with the common breakpoints in t(11;22) as shown by a translocation-specific PCR assay. Loss of heterozygosity analysis of breast tumor tissue revealed deletion of the normal chromosome 22, but retention of der(22) in the tumor cells, suggesting a predisposing effect of the der(22) for breast and brain tumor development in this family.

Cryptic duplication of the distal segment of 22q due to a translocation (21;22): three case reports and a review of the literature

Duplications of the proximal segment of chromosome 22q are not uncommon, like Cat-eye syndrome and duplications due to familial (11;22) translocations. However, duplications of the distal long arm of chromosome 22 (22qter) seem to be exceedingly rare. So far, duplications of 22q12 or 22q13 to 22qter have been described in 21 patients, of whom 13 had a pure duplication 22qter. Here we report on three new cases with a pure duplication of the distal part of 22q. The first patient carries a duplication of terminal 22q due to a de novo unbalanced translocation, 46,XX,der(21)t(21;22) (p13;q13.2), detected by NOR-staining, while the other patients have a familial cryptic duplication of terminal 22q due to an unbalanced translocation, 46,XY,der(21)t(21;22)(p10;q13.3). The last two patients were initially thought to have a polymorphic variant of 21p, but additional subtelomeric screening using FISH showed the extra material was derived from chromosome 22. Terminal duplications of 22qter may be more common than generally assumed, but due to its small size, especially when located on an acrocentric chromosome and/or possibly relatively mild phenotype remain undetected thus far.

A unique case of der(11)t(11;22),-22 arising from 3:1 segregation of a maternal t(11;22) in a family with co-segregation of the translocation and breast cancer

OBJECTIVE

To report the first tertiary monosomy in a pregnancy loss to a female t(11;22) carrier.

METHODS

The patient was a 34-year-old G10P1 female known to have a balanced translocation t(11;22)(q23;q11.2). She had one female livebirth (a translocation carrier) and eight miscarriages. Five female relatives known to be translocation carriers had a history of breast cancer, three of them premenopausally. The patient herself had a malignant melanoma.

RESULTS

During the 10th pregnancy, ultrasound showed a viable embryo at 6 weeks of gestation, but loss of embryonic heartbeat by 7.5 weeks. Culture of the products of conception at 8 weeks of gestation showed the karyotype: 46,XY,+2,der(11)t(11;22)(q23;q11.2)mat,-22[4]/45,XY,der(11)t(11;22)(q23;q11.2)mat,-22[4], resulting from fertilization of the maternal 3:1 segregation product containing only the der(11) by a normal gamete. Subsequently, she became pregnant with a normal 46,XX fetus. FISH analysis indicated that the breakpoints on 11q and 22q in the patient were in the previously described region common to typical recurrent t(11;22). In addition, a nested-PCR-based approach showed that they were located within the same palindromic AT-rich sequence previously described.

CONCLUSION

This case demonstrates that the tertiary monosomy resulting from the 3:1 segregation is compatible with embryonic survival into the first trimester. It is also another example of apparent association of the constitutional translocation t(11;22) and breast cancer.

Molecular cytogenetic insights into the ageing syndrome Hutchinson-Gilford Progeria (HGPS)

Hutchinson-Gilford Progeria Syndrome (HGPS) is an extremely rare genetic disorder characterized by premature ageing in childhood and serves as a valuable model for the human ageing process in general. Most recently, point mutations in the lamin A (LMNA) gene on chromosome 1q have been associated with the disease, however how these mutations relate to the complex phenotype of HGPS remains to be established. It has been shown that fibroblasts from HGPS patients are frequently resistant to immortalization with telomerase (hTERT), consistent with the idea that the loss of a dominant acting HGPS gene is a pre-requisite for immortalization. In this study we report the first detailed cytogenetic analysis of hTERT-immortalised HGPS cell lines from three patients and one corresponding primary fibroblast culture. Our results provide evidence for a cytogenetic mosaicism in HGPS with a distinctive pattern of chromosome aberrations in all the HGP clones. Chromosome 11 alterations were observed at a high frequency in each immortalised HGPS cell line but were also present at a lower frequency in the corresponding primary cells. Moreover, we were able to identify the 11q13-->q23 region as a potential site of breakage. Our results are therefore consistent with a role of chromosome 11 alterations in the escape from senescence observed in HGPS cells. In addition to this defined rearrangement, we consistently observed complex chromosomal rearrangements, suggesting that HGPS displays features of chromosomal instability.

Anesthesia in a patient with chromosome 11;22 translocation: a case report and literature review

Chromosome 11;22 translocation is a rare genetic condition, which results in characteristic features some of which may present problems when these children require surgery and anesthesia. We describe a child with this chromosomal variant who presented for surgery and anesthesia. The case report and review of the literature is presented here.

ETS family of genes in leukemia and Down syndrome

The human ETS2 and ERG genes are members of the ETS gene family, with sequence homology to the viral ets gene of the avian erythroblastosis retrovirus, E26. These genes are located on chromosome 21 and molecular genetic analysis of Down syndrome (DS) patients with partial trisomy 21 suggested that ETS2 may be a gene within the minimal DS genetic region. We have, in fact, been able to confirm the presence of the ETS2 gene dosage in triplicate occurring in occult human 21 chromosome abnormalities. It is known that ERG and ETS2 gene translocations occur in certain specific leukemias associated with defined chromosome rearrangements [e.g., t(8;21)]. Moreover, it is known that DS individuals are at greater risk for leukemic disease than their normal familial cohorts, implying that trisomy of that region of human chromosome 21 may play a role in the development of this type of neoplasia. The human ETS genes, first identified in our laboratory, are highly conserved, being found from lower organisms, like Drosophila and sea urchin, to humans. In mammals, the ETS genes are structurally distinct, located on separate chromosomes; they are transcriptionally active and differentially regulated. The ETS2 protein is phosphorylated and turns over with a half-life of approximately 20 min. After activation with the tumor promoter, TPA, the level of ETS2 elevates 5- to 20-fold. The properties of the ETS2 protein, such as nuclear localization, phosphorylation, rapid turnover, and response to protein kinase C, indicate that this protein belongs to a group of oncogene proteins thought to have regulatory functions in the nucleus. In the mouse thymus ets-1 and ets-2 are 8-10-fold higher, respectively, in the CD4+ subset than in other subsets examined, suggesting a role in T-cell development for these genes. Cells transfected with the cellular ets-2 gene, expressing higher levels of ets-2 products, showed a stimulated proliferation response, abolished their serum requirement and formed colonies in soft agar that could induce tumors in nude mice. Collectively, these data suggest that this family of genes might play a role in controlling specific steps of the signaling transduction pathway. Thus, the ETS genes, as other genes with homology to viral oncogenes, might be instrumental in regulating cellular growth and differentiation, as well as organismal development.

Preferential alternate segregation in the common t(11;22)(q23;q11) reciprocal translocation: sperm FISH analysis in two brothers

Segregation behaviour studies in t(11;22) carriers have reported controversial results. Whereas some authors have detected a preponderance of 3:1 products, no evidence of such prevalence was found by others. This study reports a fluorescence in-situ hybridization (FISH) segregation analysis on decondensed spermatozoa in two brothers, carriers of the same t(11;22)(q23;q11) rearrangement. Data revealed a similar meiotic segregation pattern in both carriers, 2:2 Alternate segregation being the most frequent (42.94 and 45%), while 3:1 genotypes were the least frequent in both patients, with percentages around 10%. The production of three chiasmata, based on the presence of G-light bands along the translocated segments and the presence of recombination sites at 11q and 22q distal regions, are proposed as the cause of a preponderance of the Alternate segregation. Interchromosomal effects involving chromosomes 13, 18, 21, X and Y were also evaluated. An increased frequency of sex chromosome disomies was detected in one patient. Reviewing the literature, a relationship between this phenomenon and the involvement of acrocentric chromosomes in the reorganization is suggested. FISH segregation and interchromosomal effects studies in spermatozoa are encouraged to gather information to establish the best approach for preimplantational genetic diagnosis in reorganization carriers.

A study of reciprocal translocations and inversions detected by light microscopy with special reference to origin, segregation, and recurrent abnormalities

We analyzed 448 independently ascertained reciprocal translocations and 220 inversions referred to our diagnostic laboratory. Twenty-eight percent of the translocations and 8.5% of the inversions arose de novo, the proportion being influenced by the method of ascertainment. It was highest, 47%, among translocations ascertained through an abnormal phenotype. With the exception of the 3:1 unbalanced segregants, the remainders were equally likely to have been paternally or maternally inherited. The segregation from balanced translocation and inversion carriers showed an equal number of offspring with a normal chromosome constitution and with a balanced rearrangement. The number of unbalanced segregants among the translocations was 2.7% where the proband was balanced, and 19.2% where the proband was unbalanced. There was only a single unbalanced inversion. A search for recurring translocations showed only the well documented t(11;22) to occur with unusual frequency in our series and those of others, and we concluded that the few other translocations that were seen on more than one occasion were likely to be identical by descent (IBD). Similarly the majority of the recurring inversions, with the exception of "common variants," seemed likely to be IBD. However, eight inversions recurred in our data and in most other series and may well be genuine independent rearrangements. A search of the known olfactory receptor (OR) loci and duplicons suggested that such sequences did not form an important contribution to the breakpoints of recurring rearrangements detected by light microscopy.

Upper airway malformation associated with partial trisomy 11q

11q trisomy is associated with a recognizable pattern of multiple malformations. Review of the literature reveals the following recurrent themes common to complex and isolated 11q trisomy: mental retardation, pre- and postnatal growth retardation, hypotonia, a distinct pattern of facial features, congenital heart defects, and limb malformations. We report four patients with partial trisomy 11q, none of which arose from the common 11/22 translocation. Three of the four patients had the previously unreported finding of upper airway obstruction secondary to a malformed epiglottis. The critical region for this malformation appears to be 11q21-23.2.

Unusual mosaic karyotype resulting from adjacent 1 segregation of t(11;22): importance of performing skin fibroblast karyotype in patients with unexplained multiple congenital anomalies

We report a patient with a mosaic karyotype resulting from an adjacent 1 segregation of the familial autosomal translocation (11;22). The karyotype seen in fibroblast is 46,XY,der(22)t(11;22)(q23.3;q11.2)/46,XY. No evidence of the abnormal cell line was seen in the cultures obtained from the lymphocytes. The clinical phenotype of the patient does not fit a particular pattern of partial monosomy 22 or partial trisomy 11. There are some features that have been previously reported in patients with trisomy 11q23 --> qter. The mosaic karyotype in our patient could be a result of a series of postzygotic mitotic events of a zygote carrying the der(22) chromosome. These mechanisms involve events that are well documented for several chromosomes. This case underscores the necessity of performing exhaustive cytogenetic analysis in patients with an abnormal phenotype with a family history of a chromosome rearrangement in fibroblast cells if lymphocyte analysis is normal.

Evolutionarily conserved low copy repeats (LCRs) in 22q11 mediate deletions, duplications, translocations, and genomic instability: an update and literature review

Several constitutional rearrangements, including deletions, duplications, and translocations, are associated with 22q11.2. These rearrangements give rise to a variety of genomic disorders, including DiGeorge, velocardiofacial, and conotruncal anomaly face syndromes (DGS/VCFS/CAFS), cat eye syndrome (CES), and the supernumerary der(22)t(11;22) syndrome associated with the recurrent t(11;22). Chromosome 22-specific duplications or low copy repeats (LCRs) have been directly implicated in the chromosomal rearrangements associated with 22q11.2. Extensive sequence analysis of the different copies of 22q11 LCRs suggests a complex organization. Examination of their evolutionary origin suggests that the duplications in 22q11.2 may predate the divergence of New World monkeys 40 million years ago. Based on the current data, a number of models are proposed to explain the LCR-mediated constitutional rearrangements of 22q11.2.

Detailed deletion mapping at chromosome 11q23 in colorectal carcinoma

Loss of heterozygosity (LOH) is frequent at the chromosomal region 11q22-q23 in several types of tumours of diverse cell origin. Previous investigations of LOH at this chromosomal region in colorectal carcinoma have been contradictory in their findings, and have only included between 1-4 loci. In order to define any regions of LOH on 11q23, we investigated 16 loci between D11S940 and D11S934 on the long arm of chromosome 11 using microsatellite analysis. Of 57 colorectal carcinomas specimens, 36 (63.2%) demonstrated LOH at one or more marker, with the highest frequencies of LOH at D11S1340 (41.0%), located between 105.13-111.97 Mb from the centromere, and D11S924 (37.1%) and D11S4107 (40.5%), both located approximately 113 Mb from the centromere. No statistically significant associations between LOH and age-of-presentation or Dukes' stage were found. LOH was observed in colorectal tumours of all Dukes' stages, including Dukes' stages A and B, suggesting that the inactivation of a tumour suppressor gene(s) on 11q23 occurs in the early stages of colorectal carcinoma. These results confirm the presence of putative tumour suppressor gene(s) at chromosome 11q23, involved in the carcinogenesis of colorectal carcinoma, and will facilitate future identification of candidate genes.

Meiotic studies of a human male carrier of the common translocation, t(11;22), suggests postzygotic selection rather than preferential 3:1 MI segregation as the cause of liveborn offspring with an unbalanced translocation

The t(11;22)(q23;q11) translocation is the only non-Robertsonian rearrangement for which there are a large number of unrelated families, apparently with the same breakpoints. These families most often have been ascertained through an abnormal child with the karyotype 47,XX or XY, +der(22) t(11;22)(q23;q11). To explain the high incidence of 3:1 segregants, rarely seen in offspring of carriers of other reciprocal translocations, a number of theoretical models have been suggested. We have used both electron microscope analysis of the synaptonemal complex (SC) and dual-color FISH to investigate the meiotic chromosome behavior in a male carrier of the translocation who has the karyotype 46,XY, t(11;22)(q23;q11). Chromosome synapsis, first-meiotic chiasma configuration, and segregation behavior of this translocation have been analyzed directly. Examination of SCs by electron microscopy showed pachytene-cross formation in 49/50 nuclei. Approximately 50% (26/50) revealed a classical fully synapsed quadrivalent. A proportion of these (10/26), however, showed some central asymmetry, suggesting heterologous synapsis. The remaining cells appeared to have incomplete synapsis. FISH analysis showed only quadrivalents in all 100 metaphase I nuclei. The chiasma frequency was increased within the interstitial segments, in comparison with the same region in normal bivalents. All types of segregation category were found in metaphase II nuclei. There was no indication of preferential 3:1 anaphase I segregation. We conclude that the +der(22) constitution in offspring of carriers of t(11;22)(q23;q11) is not likely to be due to meiotic 3:1 segregation being especially common. Rather, the +der(22) constitution is more likely to be the result of postzygotic selection against other unbalanced karyotypes.

Normal cardiovascular development in mice deficient for 16 genes in 550 kb of the velocardiofacial/DiGeorge syndrome region

Hemizygous interstitial deletions in human chromosome 22q11 are associated with velocardiofacial syndrome and DiGeorge syndrome and lead to multiple congenital abnormalities, including cardiovascular defects. The gene(s) responsible for these disorders is thought to reside in a 1.5-Mb region of 22q11 in which 27 genes have been identified. We have used Cre-mediated recombination of LoxP sites in embryonic stem cells and mice to generate a 550-kb deletion encompassing 16 of these genes in the corresponding region on mouse chromosome 16. Mice heterozygous for this deletion are normal and do not exhibit cardiovascular abnormalities. Because mice with a larger deletion on mouse chromosome 16 do have heart defects, the results allow us to exclude these 16 genes as being solely, or in combination among themselves, responsible for the cardiovascular abnormalities in velocardiofacial/DiGeorge syndrome. We also generated mice with a duplication of the 16 genes that may help dissect the genetic basis of "cat eye" and derivative 22 syndromes that are characterized by extra copies of portions of 22q11, including these 16 genes. We also describe a strategy for selecting cell lines with defined chromosomal rearrangements. The method is based on reconstitution of a dominant selection marker after Cre-mediated recombination of LoxP sites. Therefore it should be widely applicable to many cell lines.

Tertiary trisomy due to a reciprocal translocation of chromosomes 5 and 21 in a four-generation family

Tertiary trisomy, or double trisomy, is a rare occurrence. We present two individuals with a previously unreported tertiary trisomy for chromosomes 5p and 21q in an eight-generation pedigree. Their phenotypes are compared with other partial trisomies of either 5p or 21q from the literature. The propositus was diagnosed with trisomy 21 at 2 years of age after a karyotype study for short stature and developmental delay. His phenotype was described as atypical for Down syndrome. He presented at 9 years of age because of pervasive behavioral problems and obesity. He was brachycephalic with a flattened nasal bridge, but he lacked other characteristics of trisomy 21. Because of lack of phenotypic evidence of Down syndrome, a repeat karyotype was obtained and showed 47,XY, +der(21)t(5;21)(p15.1; q22.1), incorporating partial trisomies of both chromosomes 5 and 21. Mother had a balanced translocation, 46, XX,t(5;21)(p15.1; q22.1); 8 other relatives were examined. The translocation originated from the maternal great-grandmother, but only the propositus and his mentally retarded aunt had a similar phenotye and the derivative chromosome. Fluorescence in situ hybridization showed absence of band 21q22.2 in the derivative chromosome of the propositus and his aunt, indicating that neither had trisomy for the Down syndrome critical region. These cases represent a unique double partial trisomy of chromosome arms 5p and 21q that occurred because of 3:1 malsegregation of a reciprocal translocation. These cases further demonstrate that phenotypic discordance with cytogenetic results dictate further investigation using advanced cytogenetic hybridization.

Ebstein anomaly associated with rearrangements of chromosomal region 11q

Ebstein anomaly (EA) is a relatively uncommon congenital heart defect and it is very rarely associated with a chromosomal anomaly. We report two distinct rearrangements of the chromosomal region 11q arm in two unrelated patients with Ebstein anomaly, renal malformation, minor anomalies, and the Pierre Robin sequence. The first patient had an interstitial deletion of chromosome 11 [46,XY,del(11)(11q21q23), and the other had a tertiary trisomy of chromosome 11qter (47,XX,+der(22)t(11;22)(q23;q11.2) Its association with either a chromosome 11q deletion or a duplication in some individuals suggests that a rearrangement of the 11q region is likely to cause a shift of the individuals' underlying liability to develop EA above a certain threshold.

Comparative mapping of the human 22q11 chromosomal region and the orthologous region in mice reveals complex changes in gene organization

The region of human chromosome 22q11 is prone to rearrangements. The resulting chromosomal abnormalities are involved in Velo-cardio-facial and DiGeorge syndromes (VCFS and DGS) (deletions), "cat eye" syndrome (duplications), and certain types of tumors (translocations). As a prelude to the development of mouse models for VCFS/DGS by generating targeted deletions in the mouse genome, we examined the organization of genes from human chromosome 22q11 in the mouse. Using genetic linkage analysis and detailed physical mapping, we show that genes from a relatively small region of human 22q11 are distributed on three mouse chromosomes (MMU6, MMU10, and MMU16). Furthermore, although the region corresponding to about 2.5 megabases of the VCFS/DGS critical region is located on mouse chromosome 16, the relative organization of the region is quite different from that in humans. Our results show that the instability of the 22q11 region is not restricted to humans but may have been present throughout evolution. The results also underscore the importance of detailed comparative mapping of genes in mice and humans as a prerequisite for the development of mouse models of human diseases involving chromosomal rearrangements.

Familial complex chromosome rearrangement ascertained by in situ hybridisation

A complex familial chromosome translocation has been ascertained by combining classical cytogenetics and CISS (chromosomal in situ suppression). Cytogenetic analysis of a chorionic villus sample with G banding showed a 47,XX,-2, +der(2)t(2;22),+der(22)t(2;22) karyotype. Analysis of peripheral blood lymphocytes from the parents by G banding and CISS showed a more complex translocation in the father: 46,XY,-2,-11,-22, +der(2) t(2;11)(q13;q23), +der(11) t(11;22) (q23;q11.2), +der(22) t(2;22) (q13;q11.2). Definitive analysis of cultured amniotic fluid cells showed a double partial trisomy of chromosomes 11 and 22. The couple decided to continue the pregnancy. The fetal karyotype was confirmed at birth. Clinical abnormalities present in our patient were typical of an unbalanced 11;22 translocation. Our findings confirm that chromosome painting techniques allow a better characterisation of complex chromosome rearrangements which may be difficult to detect in G banded karyotypes.

Unusual segregation of t(11;22) resulting from crossing-over followed by 3:1 disjunction at meiosis I

Reciprocal translocation t(11;22)(q23;q11) is of particular interest because the unbalanced offspring of the translocation carriers usually present with a supernumerary derivative chromosome 22. This common unbalanced karyotype is the result of 3:1 chromosome segregation during meiosis. We report the third case of a rare segregation pattern of a paternal 11;22 translocation. The proband's karyotype revealed the presence of a der(11) and two copies of a der(22), i.e. 47,XX,t(11;22)(q23;q11),+der(22) t(11;22)pat. The karyotype is the result of paternal 3:1 segregation after crossing-over involving the derived and the normal chromosome 22, as revealed by chromosome polymorphism analysis. Contrary to the preferential maternal, transmission of this common unbalanced translocation, the data from the literature, including our case, may suggest preferential paternal transmission of this rare type of unbalanced translocation.

Der(22)t(11;22) resulting from a paternal de novo translocation, adjacent 1 segregation, and maternal heterodisomy of chromosome 22

The t(11;22) (q23;q11) translocation is the most frequently identified familial reciprocal translocation in humans. In translocation carriers, 3:1 meiotic segregation with tertiary trisomy can occur resulting in abnormal progeny with the der(22) as the supernumary chromosome. Affected children have a distinct phenotype with multiple anomalies and severe mental retardation. We have identified a child with developmental delay and multiple anomalies consistent with the der(22) phenotype. Cytogenetic analysis showed an abnormal chromosome complement of 47,XX,+der(22)t(11;22)(q23; q11) in all 50 cells analysed. FISH analysis using chromosome 11 and 22 painting probes showed a pattern consistent with a reciprocal translocation of the distal bands 11q23 and 22q11 respectively. Parental karyotypes were normal. RFLP analysis of locus D22S43, which maps above the t(11;22) breakpoint, showed that the der(22) was paternal in origin and indicated that the normal chromosomes 22 were the probable result of maternal heterodisomy. RFLP analysis of locus D22S94, which maps below the t(11;22) breakpoint, also suggested that both normal chromosomes 22 of the child represented the two maternal homologues. Non-paternity was excluded through the analysis of 10 microsatellite markers distributed on 10 different chromosomes and three VNTRs on three different chromosomes. To the best of our knowledge, this is the first reported case of a patient with an abnormal karyotype resulting from a de novo translocation in the paternal germline with probable unbalanced adjacent 1 segregation and maternal non-disjunction of chromosome 22 in meiosis I.

Cerebral defects confirm midline developmental field disturbances in supernumerary der(22), t(11;22) syndrome

We describe a girl with midline defects and distal limb anomalies, who had a supernumerary der(22) syndrome. The presence of some anomalies identifying the midline defects, led us to review all patients reported up to now, with interesting results. We point out the particular finding of midline defects in CNS only, in patients studied by autopsy or neuroradiologic imaging.