Additional chromosome in a child as a result of a balanced reciprocal translocation t(12;18)(p13;q12) in his mother's karyotype

In this case report we present a child with an additional chromosome in the karyotype. The karyotypes of the boy and his parents were analyzed by use of a conventional banding technique (GTG) and fluorescence in situ hybridization (FISH). Probes painting whole chromosomes 12 and 18 were used in FISH. Cytogenetic examination of the parents revealed that his mother was carrying balanced reciprocal translocation between chromosomes 12 and 18. Her karyotype was described as 46,XX,t(12;18)(p13;q12). Father's karyotype was normal, described as 46,XY. The boy's karyotype was defined as 47,XY,+der(18)t(12;18)(p13;q12). The additional chromosome appeared probably due to 3:1 meiotic disjunction of the maternal balanced translocation, known as tertiary trisomy. The mother displayed a normal phenotype and delivered earlier a healthy child. However, the boy with the unbalanced karyotype shows multiple congenital abnormalities.     

Balanced t(4,15)(q27,q25) translocation in a man with an exacerbated familial anamnesis

A karyological examination of a clinically healthy marital couple with aggravated anamnesis (a child with multiple congenital anomalies died on the second day after birth) revealed balanced translocation 46xy t(4, 15) (4pter----4q27 : : 15q25----15qter; 15pter----15q25 : : 4q27----4qter) in the husband.     

A rare insertional translocation of proximal segment with heterochromatic region of 1q into 7p in monozygotic twins and spontaneous abortions

Summary We present a family identified through a healthy 20-year-old female with a history of multiple successive spontaneous abortions. Her karyotype demonstrates a rare balanced insertional translocation between chromosomes 1 and 7, 46,XX,dir ins(7;1)(p15.3;q12q21.3). This is the first reported case of a 7;1 insertional translocation involving the proximal segment of chromosome 1 and may well be the cause of the multiple spontaneous abortions in our proband.     

A new RFLP withStuI and probe cX55.7 (DXS105) and its usefulness in carrier analysis of fragile X syndrome

Summary The case of a healthy 29-year-old woman is reported who had a history of three early spontaneous abortions. Chromosomal analysis of the mother of the patient showed a balanced karotype of 46,XX,t(6;11)(q24; q21), whereas the chromosomes of her father were normal. The karotype of this patient is thus a combination of a familial translocation 6;11 and a de novo translocation 4;11, which is very rare.     

46,XX, der(15),t(Y;15)(q12;p11) karyotype in an azoospermic male

We report on a Yq/15p translocation in a 23-year-old infertile male referred for Klinefelter Syndrome testing, who had azoospermia and bilateral small testes. Hormonal studies revealed hypergonadotropic hypogonadism. Conventional cytogenetic procedures giemsa trypsin giemsa (GTG) and high resolution banding (HRB) and molecular cytogenetic techniques Fluorescence In Situ Hybridization (FISH) performed on high-resolution lymphocyte chromosomes revealed the karyotype 46,XX, t(Y;15)(q12;p11). SRY-gene was confirmed to be present by classical Polymerase Chain Reaction (PCR) methods. His father carried de novo derivative chromosome 15 [45,X, t(Y;15)(q12;p11)] and was fertile; the karyotype of the father using G-band technique confirmed a reciprocal balanced translocation between chromosome Y and 15. In the proband, the der (15) has been inherited from the father because the mother had a normal karyotype (46,XX). In the proband, the der (15) could have produced genetic imbalance leading to unbalanced robertson translocation between chromosome Y and 15, which might have resulted in azoospermia and infertility in the proband. The paternal translocation might have lead to formation of imbalanced ova, which might be resulted infertility in the proband. Sister''s karyotypes was normal (46,XX) while his brother was not analyzed.     

Successive spontaneous abortions including one with whole-arm translocation between chromosomes 2

Summary A family with five induced and seven spontaneous abortions and no live births is described. Four of the seven spontaneous abortuses were available for cytogenetic examination and three were successfully karyotyped. Their karyotypes were 46,XX; 46,XX/46,XX,t(2;2)(2p2p;2q2q); and 46,XY. The karyotypes of the parents were normal. The origin of the 2p/2p and 2p/2p translocation in one of the abortuses was assigned to an interhomologous whole-arm translocation in an early mitotic division in a conceptus with a 46,XX karyotype.     

Mosaic 13 trisomy due to de novo 13/13 translocation with subsequent fission karyotype: 46,XX,-13,+t(13;13)(p11;q11)/46,XX,del(13)(p11)

Summary A severely retarded child with multiple malformations was found to present a mosaic karyotype 46,XX,-13,+t(13;13)(p11;q11)/46,XX,del (13)(p11), which probably originated as the result of a de novo 13/13 translocation in a parental gamete, followed by postzygotic fission of the translocation chromosomse.     

Prenatal cytogenetic analysis of women with high risk for genetic disorders

165 prenatal cytogenetic analyses are reported. The culture and Giemsa or quinacrine mustard (QM) staining processes are described. Karyotypes from both Giemsa and QM metaphases were analyzed. The main indications for amniocentesis were: 1)previous child with Down's syndrome (65), 2)advanced maternal age (74), 3)D/G carrier (5), 4)Duchenne muscular dystrophy (5) or 6)previous indication of other chromosomal anomaly. In the advanced maternal age group, 4 G21 and 1 E18 trisomy fetuses were detected. No chromosomal abnormalities were seen in the group referred for a previous child with Down's syndrome, although one woman was found to have a 9/13 translocation herself. Another woman with 13/14 translocation gave birth to a healthy boy with a 13/14 translocation, as predicted. Of 5 women referred for D/G translocation carriers, 1 had a fetus with a 46, X,Y,-D + t(DqGq) karyotype. Sex determination for X-linked anomalies resulted in detection of 2 Duchenne's muscular dystrophy, 1 hemophilia, 1 Norrie's syndrome, and 1 Pelizaeus-Merzbacher's syndrome.     

Two cases of partial trisomy 10q syndrome due to a familial 10;20 translocation

We describe an eleven day-old boy and his first degree double cousin who both have distal trisomy 10q syndrome. Their cytogenetic analysis using GTG-banding showed an unbalanced translocation 46, XY, -20, +der(20), t(10;20)(q22.3, p11) mat and 46, XX, -20, +der(20), t(10;20)(q22.3, p11) mat. The translocation was confirmed by FISH. We have found balanced translocation t(10;20)(q22.3; p11) with cytogenetic and FISH studies in the mothers and maternal grandfather of these children. Our cases had typical craniofacial and visceral anomalies of this syndrome. However case 1 had an agenesia of corpus callosum which was not previously described and case 2 had hypertrophied cardiomyopathy and cliteromegaly which were previously described as rare anomalies for this syndrome.     

Studies on chiasma frequency and distribution in two fertile men carrying reciprocal translocations; one with a t(9;10) karyotype and one with a t(Y;10) karyotype

Summary The frequency and distribution of chiasmata was investigated in two fertile carriers of reciprocal translocations, one with a 46,XY,t(9;10)(p22;q24) karyotype and one with a 46,X,-Y,+der(Y),t(Y;10)(q12;q24) karyotype. In both cases the chromosomes involved in the translocation showed an increase in chiasma frequency in comparison to karyotypically normal controls and in both cases this increase was localised, affecting only one interstitial segment of each translocation quadrivalent. In the t(9;10) case chiasmata appeared in substantial numbers in a novel location, the proximal two thirds of 9p, while in the t(Y;10) case chiasmata appeared in a conventional location, the medial region of 10q, but at an increased frequency. Furthermore there was evidence for inter-chromosomal effects in the t(9;10) case.     

Joubert syndrome co-existing with partial Xp trisomy: review of the literature

We report a five-year-old girl who has been clinically diagnosed as Joubert syndrome. Her cytogenetic analysis showed 46,XX,der(2)add(2q37) karyotype. Cytogenetic analysis of her mother and maternal grandmother revealed a karyogram designated as 46,X,t (X;2)(p11.2;q37). The proband's derivative chromosome was further confirmed to be a translocation chromosome 2 carrying segments from chromosome X, which originated from a segregation event of the maternal grandmother's balanced translocation passed on as a balanced translocation to the proband's mother either. So far, a number of candidate genes including EN1 on 2q were analyzed for Joubert syndrome. Based on our proband's abnormal karyotype, we suggest that further mapping studies for the syndrome should also be directed towards the chromosome X segments present on the derivative chromosome 2 of our proband.     

Familial (9;11)(p22;p15.5)pat translocation and XX sex reversal in a phenotypic boy with cryptorchidism and delayed development

We describe a patient with the co-occurrence of a familial 9;11 reciprocal translocation and an XX sex reversal. The patient had cryptorchidism, delayed development, dysmorphic features and attention deficiency hyperactive disorder (ADHD). The proband's karyotype was 46,XX,t(9;11)(p22;p15.5) and he was positive for SRY gene. The father was found to be the carrier of the similar translocation. The co-occurrence of XX sex reversal and autosomal reciprocal translocation has not been described previously. The possible reasons for the manifestation of features other than those found in XX sex reversal is described.     

A prevalent Y;15 translocation in the Ethiopian Beta Israel community in Israel

We describe 7 cases of abnormal karyotypes involving chromosomes Y and 15 in Ethiopian Beta Israel patients: 46,XX, der(15)t(Y;15)(q12;p12) and 46,XY,der(15)t(Y;15)(q12;p12). Six cases were incidentally found in amniocentesis performed for various indications; the indication for karyotyping in 1 case was recurrent abortions. To the best of our knowledge, this is the first report of this translocation in a specific ethnic group. We conclude that the derivative chromosome 15 with chromosome Y is probably a normal variant in Ethiopian Beta Israel occurring at an estimated frequency of 4/74 (5.4%). The prenatal diagnosis of this translocation in this population probably does not require further parental testing.     

Clinical and cytogenetic study of a case with familial chromosomal translocation presenting with facial dysmorphism and axial neuropathy

We report on a 9-year-old female patient presenting with muscle weakness, facial dysmorphism and mild mental retardation. She had low birth weight, developmental delay, hypotonia and hyporeflexia and difficulties in climbing the stairs. EMG revealed axonal polyneuropathy affecting both upper and lower limbs. She was the child of non-consanguineous parents, her cytogenetic findings revealed 46,XX,t(12;14)(q14;q23). The mother's karyotype was normal 46,XX while the father's karyotype was 46,XY,t(12;14)(q14;q23) the same as his daughter. Her normal sister's karyotype was also 46,XX,t(12; 14) (q14;q23). Fluorescence in situ hybridization (FISH) was used to elucidate the breakpoints and Array-CGH was done for the patient to confirm the balanced translocation. This observation is of interest because it represents a rare case of a balanced translocation with abnormal phenotype. Mutant genes causing axonal neuropathy have been located on various chromosomes other than 12q14 or 14q24. This report shows the importance of molecular cytogenetics and its correlation with abnormal phenotype and the possibility of another gene locus at the presently studied chromosomal breakpoints. Detailed correlations between chromosome aberrations and their phenotypes are of invaluable help in localising genes for axonal polyneuropathy.     

rDNA and acrocentric chromosomes in man

Summary A malformed female infant was found to have a 46,XX complement with a chromosome 8 shorter than normal with a secondary constriction and satellites on the short arm. Chromosome studies on the clinically normal father showed a balanced translocation between chromosome 8 and 13, i.e., 46,XY,t(8;13) (p21 p12). The proposita, carrier of the unbalanced form of the translocation, resulted partially monosomic for short arm of chromosome 8 (8p-) and partially trisomic for short arm of chromosome 13.The levels of DNA complementary to rRNA (normal in the father who had 10 NOR and increased in the proposita who had 11 NOR) confirmed our interpretation of the rearrangement.     

Partial trisomy 14q due to maternal t(4;14)(p16;q32) in a dysmorphic newborn

Partial Trisomy 14q is a rare chromosomal disorder that mostly results from a parental translocation. We report here a newborn boy with partial trisomy 14q and dysmorphic features that are compatible with previously reported cases. Conventional cytogenetic analysis revealed an extra chromosomal segment at the end of the short arm of chromosome 4. In order to determine the origin of this chromosome region we used subtelomeric FISH technique. Based on the results of these cytogenetic studies and the physical examination, this dysmorphic case was diagnosed as partial trisomy of 14q and his karyotype determined as 46 XY, der(4)t(4;14)(p16;q32) resulting from a balanced maternal translocation identified as 46,XX, t(4;14)(p16;q32).     

Partial trisomy 12 and 8 with mosaicism, associated with translocation t(8;12) (p21;q13)]

A translocation affecting chromosomes 8 and 12 was detected in 11 persons of 3 generations of a family. The propositus, a child with multiple malformations, had a mosaicism consisting of (a) cells with 46 chromosomes which included the balanced translocation and (b) cells with 47 chromosomes and partially trisomic for chromosomes 8 and 12.     

A dynamic study in two new cases of X chromosome translocations

Summary The authors discuss the clinical and cytogenetic problems raised in two new cases of X-chromosome translocations.The first case involves a child who presented marked growth retardation, behavioral anomalies, and discrete facial malformations at age 3 months. Chromosome analysis revealed the presence of a translocation between a 22 and X chromosome resulting in partial X monosomy and partial trisomy 22: 46,X,der(X),t(X;22)(q112;q13)mat. The balanced translocation form was detected in the mother. Dynamic study after 5-Brdu treatment revealed inactivation of the translocated X chromosome in the proband, while in the mother the normal X chromosome was inactivated.In addition to magnesium dependent hypocalcemia resulting from a specific absorption anomaly, Case 2 presented discrete malformations and psychomotor retardation. Chromosome analysis revealed an apparently balanced translocation between a 9 and X chromosome: 46,X,r(9;X)(q12; p22). Treatment with 5-Brdu demonstrated that the translocated X chromosome was inactivated but that inactivation did not extend to the translocated part of chromosome 9. Finally, a pericentric inversion of a 9 chromosome was detected in the father, grandfather, and brother of the proband.     

DNA methylation analysis of ade novo balanced X;13 translocation in a girl with abnormal phenotype: evidence for functional duplication of the whole short arm of the X chromosome

We report on a 13-month-old girl showing dysmorphic features and a delay in psychomotor development. She was diagnosed with a balancedde novo translocation 46, X, t(X;13)(p11. 2;p13) and non-random inactivation of the X chromosome. FISH analysis, employing the X chromosome centromere andXIST-region-specific probes, showed that theXIST locus was not involved in the translocation. Selective inactivation of paternal X, which was involved in translocation, was revealed by the HUMARA assay. The pattern of methylation of 5 genes located within Xp, which are normally silenced on an inactive X chromosome, corresponded to an active (unmethylated) X chromosome. These results revealed that in our proband the X chromosome involved in translocation (Xt) was preferentially inactivated. However, genes located on the translocated Xp did not includeXIST. This resulted in functional Xp disomy, which most probably accounts for the abnormal phenotype in our patient.     

Partial trisomy 13 as a result of de novo (6p;13q) translocation

Summary A newborn infant with the clinical features of the Patau syndrome was found to have excess chromosome 13 material present as a tandem translocation involving the short arm of chromosome 6 and the long arm of an extra chromosome 13: 46,XY,t(6;13)(p24;q12). The major part of the long arm of the extra chromosome 13 was attached linearly (tandem translocation) to the short arm of chromosome 6. Both parents were phenotypically and karyotypically normal.