Maternal Translocation Research Articles

Cytogenetic analysis in 16-year follow-up study of a mother and fetus exposed in a radiation accident in Xinzhou, China

In November 1992, a radiation accident occurred in Xinzhou, due to the collection by a farmer of an unused 60Co source; 37 individuals were exposed to ionizing radiation. Three individuals died and the farmer's 19-weeks-pregnant wife suffered acute radiation symptoms. Conventional chromosome analysis, cytokinesis-block micronuclei (CBMN) assay and fluorescence in situ hybridization (FISH) painting with three pairs of whole chromosome probes were used to analyze chromosomal aberrations for the pregnant female and her baby during the 16 years following the accident. The yields of dicentrics and rings (dic+r) continually declined between 41 days and 16 years after the accident. The frequency of binucleated MN also decreased over time for both mother and daughter. Sixteen years after exposure, the yields of dic+r and binucleated MN decreased to normal levels, but the reciprocal translocation frequencies remained elevated, for both mother and daughter. FISH results showed a decreasing yield of translocations with time. Based on the changes in maternal translocation frequency, the daughter's dose at the time of exposure was estimated as 1.82 (1.35–2.54)Gy. This was consistent with the clinical manifestations of severe mental retardation and low IQ score. FISH-based translocation analysis can be used for follow-up studies on accidental exposure and, after correction, for retrospective dose estimation for individuals prenatally exposed to radiation.

Partial trisomy of the long arm of chromosome 1: Prenatal diagnosis, clinical evaluation and cytogenetic findings. Case report and review of the literature

Partial trisomy of the long arm of chromosome 1 is a relatively rare cytogenetic anomaly. Its phenotype has still not been completely defined, because of the cytogenetic heterogeneity of the cases so far described. We report a prenatal case of partial 1q trisomy associated with partial monosomy 4q, secondary to balanced maternal translocation t(1;4). The trisomic segment extended from 1q31.1 to qter and the monosomy 4q was from 4q35.2 to qter. The phenotypic anomalies found by post-mortem and autopsy examinations were compared with those of similar cases reported in the literature. We performed standard cytogenetics and fluorescence in situ hybridization. Cerebral ventriculomegaly, present in our case, seemed to be a constant feature in partial 1q trisomies, so this cerebral malformation could be considered as the main echographic marker for this chromosomal imbalance and trisomy 1q should be added to the list of chromosomal abnormalities associated with ventriculomegaly.

Familial Turner syndrome with an X;Y translocation mosaicism: Implications for genetic counseling

Spontaneous fertility is rare among patients with Turner syndrome and is most likely in women with mosaicism for a normal 46,XX cell line. We report an unusual case of familial Turner syndrome with mosaicism for a novel X;Y translocation involving Xp and Yp. The chromosomal analysis was carried out through cytogenetics and molecular karyotyping using a SNP array platform. The mother, a Turner syndrome woman, diagnosed in midchildhood because of short stature, was found to have a 45,X/46,X,der(X)t(X;Y)(p11.4;p11.2) karyotype, with a predominant 45,X cell line. Her parents decided against prophylactic gonadectomy, generally recommended at an early age when Y chromosome has been identified, because at age 13, she had spontaneous puberty and menarche. She reached a final height of 154 cm after treatment with growth hormone. At age 24, she became spontaneously pregnant. She had a mild aortic coarctation and close follow-up cardiac evaluation, including cardiac magnetic resonance imaging, had been performed during her pregnancy, which progressed uneventfully, except for intra-uterine growth retardation. Prenatal diagnosis revealed a female karyotype, with transmission of the maternal translocation with an unexpected different mosaic:47,X,der(X)t(X;Y)x2/46,X,der(X)t(X;Y) karyotype. This complex and unusual karyotype, including a mosaic partial trisomy X and a non-mosaic Xpter-Xp11.4 monosomy, results in transmission of Turner syndrome from mother to daughter. At birth, the girl had normal physical examination except for growth retardation. This family illustrates the complexity and difficulties, in term of patient counseling and management in Turner syndrome, in determining ovarian status, fertility planning, risks associated with pregnancies, particularly when mosaicism for Y material chromosome is identified.

A Case with Emanuel Syndrome Resulting from a Maternal Balanced Translocation

A Case with Emanuel Syndrome Resulting from a Maternal Balanced Translocation

Maternal gametic transmission of translocations or inversions of human chromosome 11p15.5 results in regional DNA hypermethylation and downregulation of CDKN1C expression

Beckwith–Wiedemann syndrome (BWS) is an overgrowth syndrome associated with genetic or epigenetic alterations in one of two imprinted domains on chromosome 11p15.5. Rarely, chromosomal translocations or inversions of chromosome 11p15.5 are associated with BWS but the molecular pathophysiology in such cases is not understood. In our series of 3 translocation and 2 inversion patients with BWS, the chromosome 11p15.5 breakpoints map within the centromeric imprinted domain, 2. We hypothesized that either microdeletions/microduplications adjacent to the breakpoints could disrupt genomic sequences important for imprinted gene regulation. An alternate hypothesis was that epigenetic alterations of as yet unknown regulatory DNA sequences, result in the BWS phenotype. A high resolution Nimblegen custom microarray was designed representing all non-repetitive sequences in the telomeric 33 Mb of the short arm of human chromosome 11. For the BWS-associated chromosome 11p15.5 translocations and inversions, we found no evidence of microdeletions/microduplications. DNA methylation was also tested on this microarray using the HpaII tiny fragment enrichment by ligation-mediated PCR (HELP) assay. This high-resolution DNA methylation microarray analysis revealed a gain of DNA methylation in the translocation/inversion patients affecting the p-ter segment of chromosome 11p15, including both imprinted domains. BWS patients that inherited a maternal translocation or inversion also demonstrated reduced expression of the growth suppressing imprinted gene, CDKN1C in Domain 2. In summary, our data demonstrate that translocations and inversions involving imprinted domain 2 on chromosome 11p15.5, alter regional DNA methylation patterns and imprinted gene expression in cis, suggesting that these epigenetic alterations are generated by an alteration in “chromatin context”.

Monosomy1p36.3 and Trisomy 19p13.3 in a Child With Periventricular Nodular Heterotopia

Monosomy 1p36 is a clinically recognizable syndrome that is considered to be the most common terminal deletion syndrome. It has characteristic clinical features that include craniofacial dysmorphism, congenital anomalies, hearing deficits, developmental delay, mental retardation, hypotonia, seizures, and brain anomalies. Brain anomalies in patients with 1p36 deletion are frequent but inconsistent. To date, 2 cases with monosomy 1p36 associated with periventricular nodular heterotopia (PNH) have been reported. We report a 2-month-old boy with multiple congenital anomalies; brain magnetic resonance imaging revealed PNH. The first 2 described cases were pure terminal deletions, whereas our patient carried unbalanced translocation due to an adjacent 1 segregation of a balanced maternal translocation, resulting in monosomy 1p36.3 and trisomy 19p13.3 identified by whole-genome array comparative genomic hybridization analysis. Our patient, with a smaller deletion that the 2 previously reported cases, can help narrow the critical region for PNH in association with the 1p36 deletion. Several potential candidate genes are discussed.

Familial 18p deletion syndrome and 18p partial trisomy inherited from a mother with balanced translocation

18p deletion syndrome can be easily missed in a clinical setting as the facial features, though typical, can be overlooked and the other features including growth retardation and learning disability are nonspecific. We present a family in which the proband has 18p deletion syndrome. The proband performed better on verbal skills than on performance tasks on intelligence testing. She had attention-deficit hyperactivity disorder, which required medication and behavioral therapy. Subsequent cytogenetic analysis in her elder brother who presented with learning difficulties showed partial trisomy 18p and the maternal karyotype is 46, XX,(15;18)(p11.2;p11.2). This is the first report of a family with a balanced maternal translocation resulting in 18p deletion in one sibling and 18p partial trisomy in the other.

Partial Trisomy 9p(p22→pter) from a Maternal Translocation 4q35 and 9p22

We present clinical and cytogenetic data on a 7-year-old female child with partial trisomy for 9p22→9pter as a result of a maternal balanced reciprocal translocation. Her karyotype was ascertained as 46,XX,dec(4)t(4;9)(q35; p22)mat. The father had a normal karyotype, while the mother had an apparently balanced translocation involving chromosomes 4 and 9 [46,XX,t(4;9)(q35;p22)]. This case will be briefly compared with other published cases of a similar translocation.

Parental karyotype may reveal the source of a pregnancy loss even in the presence of a reportedly euploid fetal karyotype

To present a case of a fetal loss in which a normal fetal karyotype was obtained by banding studies. Identification of an abnormal maternal karyotype prompted subsequent reanalysis using fluorescence in situ hybridization (FISH). Case report. University-affiliated IVF center. A 32-year-old woman, G1 P0, underwent a fetal loss at 8 weeks, and a suction curettage was performed. The patient had a previous first-trimester loss. The fetal tissue was evaluated by banding studies and found to be normal. Parental karyotyping was performed, and the fetal tissue was reanalyzed by FISH. Analysis of fetal karyotype by targeted FISH. Maternal karyotype demonstrated a translocation [46,XX, t(8;10)(q24.3:q25.2)]. The fetal tissue was reanalyzed by FISH, and a segment of chromosome 10 was found on chromosome 8. A normal fetal karyotype, as measured by banding, does not exclude a genetic etiology for pregnancy loss. In this case, maternal translocation prompted the genetics laboratory to search for a small segment of translocated extra chromosomal material. This demonstrated that despite the finding of a normal fetal karyotype, in some cases parental karyotyping may have value.

1q44-qter Trisomy:Clinical Report and Review of the Literature

Subtelomeric rearrangements are one of the main causes of multiple congenital anomalies and mental retardation, and they are detected in 5% of patients. We report on a 6.5-year-old boy with mental retardation, dysmorphic features, and behavioral problems, who revealed 1q44-qter trisomy and 22q13.3-qter monosomy due to a maternal cryptic translocation t(1;22). We compared the clinical and cytogenetic data of our patient with those of another case presenting a pure 22qter monosomy and with those of all 1qter trisomy cases reported in the international literature. To the best of our knowledge, the subterminal 1q trisomy found in the present case has been reported in only 12 patients to date (including five familial cases). This report aims to contribute to our understanding of 1q44-qter trisomy.

Corpus Callosum Agenesis in Trisomy 8p11.23 and Monosomy 4q34 Because of Maternal Translocation

We report on a 3-year-old boy with partial trisomy 8 p11.23-->pter and partial monosomy 4q34-->qter, associated with developmental delay, complete agenesis of the corpus callosum, and mild dysmorphic features. Although agenesis of the corpus callosum is not a rare finding among chromosomal abnormalities, partial trisomy 8p together with partial monosomy 4q, resulting from a maternal translocation, was not previously reported, to the best of our knowledge.

Polar Body Diagnosis – A Step in The Right Direction?

Polar body diagnosis (PBD) is a new diagnostic method for the indirect genetic analysis of oocytes, which is carried out as part of in vitro fertilization. The biopsy of polar bodies is technically demanding and cannot be adopted uncritically in routine practice, in the absence of robust data to support this laboratory procedure. Selective literature review and analysis of own PBD data. The main application of PBD is the detection of chromosomal aneuploidies and maternally inherited translocations in oocytes. The major disadvantage of PBD is that the paternal contribution to the genetic constitution of the developing embryo cannot be evaluated. Moreover, the potential value of polar body biopsy for the diagnosis of monogenetic diseases is limited. The role of PBD in improving of success rates in assisted reproduction requires evaluation in further clinical trials. For maternal translocations, PBD can be used to reduce the risk of miscarriage. Rapid development in the field of molecular diagnostic and biopsy techniques will also influence PBD and will most likely allow wider application of this method in the near future.

Long‐term follow‐up of a 26‐year‐old male with duplication of 16p: Clinical report and review

We report on a 26-year-old male with profound psychomotor retardation and a pattern of dysmorphic features and malformations characteristic for duplication of the short arm of chromosome 16. He has an elongated face, sparse hair, upslanting palpebral fissures, anteverted nostrils, hypoplastic thumbs on both hands, and dislocation of several joints. His chromosome aberration was diagnosed at birth and was due to an unbalanced segregation of a maternal translocation t(2;16)(q36;p11). At 26 years of age he is, to the best of our knowledge, the oldest patient with duplication of 16p reported to date. We present a long-term observation of growth, psychomotor development, dysmorphic features and evolution of his skeletal and joint defects as well as a review of the literature.

Dandy-Walker malformations in a case of partial trisomy 9p (p12.1→pter) due to maternal translocation t(9;12)(p12.1;p13.3)

We describe a five-year-old proband presented with Dandy-Walker malformations, right microopthalmia, hamstring contractures, undescended testis with absence of testis in right scrotum in addition to typical trisomy 9p clinical features. Routine cytogenetic studies with GTG - banding showed 46,XY,der(12)t(9;12) (p12;q13.3),mat karyotype (trisomy 9p). Chromosomal analysis of the father was normal and phenotypically normal mother had 46,XX,t(9;12)(p12;q13) karyotype. Fluorescence in situ hybridization analysis with single copy probes bA5OIA2 (9p11.2), bA562M8 (12p12.1) and centromere probes (9) showed break point at 9p12.1 region. The gene dosage effect of Chromosome 9p along with environmental factors might be associated with Dandy- Walker malformations in the patient.

Prenatal foetal diagnosis of partial trisomy 3q and monosomy 13p due to a maternal balanced rearrangement

The authors describe a case of a male foetus whose ultrasound at 20 weeks' gestation revealed cystic hygroma, cleft lip and ventricular septal defect. Amniotic fluid cytogenetics using GTG banding showed a 46,XY,der(13)t(3;13)(q12;p11.1) rearrangement, and fluorescence in situ hybridization (FISH) delineated the relevant breakpoints. Familial studies identified a maternal balanced translocation involving chromosomes 3 and 13. The post-mortem examination confirmed the prenatal ultrasound findings.

Trisomy 8p (p11.2-pter) due to maternal translocation t(8;13)(p11;p12) in a child with dysmorphic features

Here we present a phenotypic description of a male child with trisomy 8p resulting from a maternal balanced reciprocal translocation. The patient presented with dysmorphic face, aplasia of the corpus callosum, and atrophy of cortex, congenital heart defect and marked hypotonia. The father had a normal karyotype. The mother had an apparently balanced translocation involving chromosomes 8 and 13 [46, XX, t(8;13)(p11.2;p12)]. The karyotype of the child was ascertained as 46, XY, der(13)t(8;13)(p11.2;p12). This is the second reported case of trisomy 8p resulting from a translocation between chromosomes 8 and 13. The chromosomal breakpoints in the two cases differed.

Complex congenital cardiac disease in a patient with partial trisomy for the long arms of chromosomes 11 and 22

Abnormalities of chromosomes 11 and 22 are associated with congenital cardiac disease and/or various syndromes. We present a patient with partial trisomy for the long arms of chromosomes 11 and 22, the result of a maternal balanced reciprocal translocation between these two chromosomes. Our patient was dysmorphic and had coarctation of the aorta, an atrioventricular septal defect with common atrioventricular junction and exclusively atrial shunting, patency of the arterial duct, supracardiac totally anomalous pulmonary venous connection, a single kidney, and tracheobronchomalacia. This patient is unusual in having extensive left-sided cardiac involvement, a feature not usually found in this condition.

Newborn with malformations and a combined duplication of 9pter-q22 and 16q22-qter resulting from unbalanced segregation of a complex maternal translocation.

We report a patient with duplication of 9pter-q22 combined with duplication of 16q22-qter. The chromosome anomaly was the result of a 3:1 segregation of a maternal translocation (46,XX,t[9;16;21]). This newborn had intrauterine growth retardation and microcephaly, the characteristic recognizable pattern of trisomy 9p, cerebellar hypoplasia, a porencephalic cyst in the parieto-occipital region, and rocker-bottom feet. We compare the clinical features with another previously described case of duplication of an identical 9p segment combined with distal 16q duplication of a similar, but not identical segment, as well as with cases with duplication of either one of the two segments.

Chromosome abnormalities and epilepsy.

Chromosome abnormalities are often associated with central nervous system (CNS) malformations and with other neurologic dysfunctions. In particular, patients with chromosomal abnormalities can have mental retardation (MR) and have a higher risk for seizures than that found in the general population (1). Genetic tools such as karyotyping, high-resolution chromosome banding, fluorescent in situ hybridization (FISH), and other molecular genetics techniques have increased the number of chromosome abnormalities detected in subjects with MR or seizures. However, the majority of studies and reports published have usually considered sporadic cases or very small groups of patients with chromosome abnormalities. Furthermore, the characteristics of seizures and EEGs have been described in detail on very few occasions, to define the electroclinical phenotype, and eventually to classify the epilepsy. In recent years, a few identified chromosome abnormality syndromes seem to show a particular clinical and EEG picture; some of them are relatively common, such as Angelman’s syndrome, the fragile-X (fra-X) syndrome, the Miller‐Dieker syndrome; and others are more rare, such as trisomy 12p syndrome, the Wolf‐ Hirschhorn syndrome, and ring 20 syndrome. We review some clinical and neurophysiologic aspects of these syndromes that can support the neurologist in choosing the genetic analysis to be carried out, and help to identify specific genes influencing epileptogenesis. ANGELMAN’S SYNDROME

Interphase FISH with chromosome-specific protelomere probes for rapid prenatal diagnosis in a reciprocal translocation carrier

Interphase fluorescence in situ hybridization (FISH) analysis has become an accepted practice for rapid preliminary analysis of chromosome aneuploidy from direct amniocyte preparations. The use of dual-color interphase FISH analysis with chromosome-specific protelomere probes for the rapid exclusion of chromosomally unbalanced segregants in the pregnancy of a reciprocal translocation carrier is reported. Amniocentesis was performed at 16 weeks gestation on the carrier of a t(5;14)(p14.2;p13), who was ascertained after the birth of a son with the der(5) chromosome. Interphase FISH analysis with probes for 5pter, 5qter and 14qter showed two signals for each, consistent with alternate segregation of the maternal translocation. Subsequent metaphase analysis confirmed a 46,XY,t(5;14)(p14.2;p13)mat karyotype in the fetus. This case illustrates the utility of interphase FISH analysis with protelomere probes for rapid prenatal diagnosis in cases of parental reciprocal translocation.