Homozygosity for a Y/22 chromosome translocation: t(Y;22) (q12;p12/13)

A newborn girl, homozygous for a balanced Y/22 chromosome translocation is described. This unique karyotype was detected during prenatal chromosome studies in the first pregnancy of a 26-year-old woman. Amniocentesis was performed because of clinical evaluation of severe fetal growth retardation in the 28th week of gestation. The cytogenetic results were confirmed using a lymphocyte culture after birth in the 30th week. Subsequent chromosome studies of the parents were hampered by the fact that the pregnancy was thought to be the result of artificial insemination with donorsperm. Nevertheless both, consanguineous, parents were shown to be carriers of the same, singular, chromosome translocation and the spermdonor could be excluded from paternity by bloodgroup- and HLA studies. Distamycin-A-DAPI chromosome staining and DNA studies of the mother were used to confirm the involvement of the Y-chromosome in this translocation. The probanda is developing quite normally at the age of 21 months.     

Familial occurrence of ring chromosome 15

We present a family with the ring 15 chromosome (r(15)) syndrome in a 2-year-old infant and his mother. Both had the common clinical manifestations reported in previous cases with r(15), including severe short stature, microcephaly, triangular face, and mild mental retardation. The family also had a normal son. Although males with r(15) syndrome usually seem to be infertile, female r(15) patients are likely to be fertile and their reproductivity may be influenced by severe growth retardation.     

Familial,balanced insertional translocation of chromosome 7 leading to offspring with deletion and duplication of the inserted segment, 7p15 → 7p21

We report an uncle and niece with duplication and deletion, respectively, of segment 7p15 → 7p21 originating from a balanced, intrachromosomal insertion in their mothers. The proposita had prenatal and postnatal growth deficiency, retarded psychomotor development, microcephaly, wide cranial sutures, ocular hypertelorism, small palpebral fissures, apparently low-set and malformed ears, cleft palate, congenital heart defect, hypoplasia of the distal phalanx of first fingers, rocker-bottom feet, persistent cloaca, and imperforate anus. She died at three months. Her maternal uncle has duplication of this segment and is alive at 32 years. He has severe mental deficiency, but normal growth; communicating hydrocephalus was diagnosed at three months.     

Familial transmission of a deletion of chromosome 21 derived from a translocation between chromosome 21 and an inverted chromosome 22

Chromosome analysis of a newborn boy with Down syndrome resulted in the identification of a family with an unusual derivative chromosome 22. The child has 46 chromosomes, including two chromosomes 21, one normal chromosome 22, and a derivative chromosome 22. Giemsa banding and fluorescent in situ hybridization (FISH) studies show that the derivative chromosome is chromosome 22 with evidence of both paracentric and pericentric inversions, joined to the long arm of chromosome 21 from 21q21.2 to qter. The rearrangement results in partial trisomy 21 extending from 21q21.2 to 21q terminus in the patient. The child's mother, brother, maternal aunt, and maternal grandmother are all carriers of the derivative chromosome. All have 45 chromosomes, with one normal chromosome 21, one normal chromosome 22, and the derivative chromosome 22. The rearrangement results in the absence of the short arm, the centromere, and the proximal long arm of chromosome 21 (del 21pter21q21.2) in carriers. Carriers of the derivative chromosome in this family have normal physical appearance, mild learning disabilities and poor social adjustment. Am. J. Med. Genet. 70:399–403, 1997. © 1997 Wiley-Liss, Inc.     

Saethre-Chotzen syndrome with familial translocation at chromosome 7p22

Chromosome analysis of a male infant and his mother with Saethre-Chotzen syndrome demonstrated an apparently balanced translocation, t(2;7)(p23;p22). This association lends support to localization of the gene for Saethre-Chotzen syndrome to the 7p2 region and supports further involvement of gene(s) in the 7p22 region. © 1993 Wiley-Liss, Inc.     

包头地区一家系染色体平衡易位的细胞遗传学分析

目的报道一家系3例染色体t（9;15）平衡易位,分析其细胞遗传学特点。方法采用外周血淋巴细胞培养技术,对一家系7人进行常规G显带核型分析。结果一家两代人中有3例染色体同为t（9;15）平衡易位。结论平衡易位是导致不良孕产史的重要原因。应做好遗传咨询指导,对不良孕产史患者进行染色体检查。     

Myotonic dystrophy and chromosome translocation segregating in the same family

We report on a family segregating the myotonic dystrophy (DM) gene and a t(5;8) reciprocal translocation. The DM presented the characteristics typically seen in this disease, i.e. full penetrance, broad expressivity, apparent anticipation in successive generations, presence of a congenital form transmitted by a carrier mother. The family was uninformative for linkage studies with the Lutheran and Secretor loci. The concordance between DM and chromosome translocation in 8 out of 9 individuals at risk was apparently due to chance.     

EEC syndrome (ectrodactyly, ectodermal dysplasia and cleft lip/palate) with a balanced reciprocal translocation between 7q11.21 and 9p12 (or 7p11.2 and 9q12) in three generations

Familial cases (a grandfather, a father and a daughter) of the EEC syndrome (ectrodactyly, ectodermal dysplasia and cleft lip/palate) are reported. All of them have a balanced reciprocal translocation (46,XY or XX, t(7;9) (q11.21;p12) or (46,XY or XX, t(7;9) (p11.2;q12)), but no other members of the family have either the EEC syndrome or chromosome abnormalities. This indicates that one of the chromosome sites 7q11.21, 9p12, 7p11.2 and 9q12 is a candidate for gene locus of the EEC syndrome.     

Possible inactivation of part of chromosome 13 due to 13qXp translocation associated with retinoblastoma

Chromosome examination of a female patient with 13/X translocation associated with retinoblastoma was carried out using peripheral blood lymphocytes and cultured skin fibroblasts. The constitutional karyotype was 46,X,t(l 3;X) (q12;p22). Q-banding analysis showed that the translocated chromosomes were of paternal origin. Studies on DNA replication pattern with Giemsa banding using the bromodeoxyuridine substitution technique revealed that the derivative X chromosome was late replicating, and the translocated chromosome 13 was affected by the spreading of lyonization. Such a functional monosomy of 13q14 may also be involved in retinal blasts, and be related to the development of retinoblastoma.     

Familial reciprocal translocation, t(2;10)(p24;q26), resulting in duplication 2p and deletion 10q

We describe a familial reciprocal translocation between the distal part of the short arm of chromosome 2 and the long arm of chromosome 10. Five individuals in two generations had multiple congenital anomalies. Their karyotypes were 46, XX or XY,−10, + der(10), t(2;10)(p24;q26). Seven persons were balanced translocation carriers whose karyotypes were 46, XX or XY, t(2;10)(p24;q26). Common manifestations included mental retardation, strabismus, narrow high-arched palate, wide alveolar ridges, other facial abnormalities, genital abnormalities and mutism. The phenotype of the unbalanced individuals is compared to that of previously published cases of the syndrome of partial duplication 2p and to reported patients with partial deletion of 10q.     

Confirmation of CHD7 as a cause of CHARGE association identified by mapping a balanced chromosome translocation in affected monozygotic twins

Background

CHARGE syndrome has an estimated prevalence of 1/10 000. Most cases are sporadic which led to hypotheses of a non‐genetic aetiology. However, there was also evidence for a genetic cause with reports of multiplex families with presumed autosomal dominant, possible autosomal recessive inheritance and concordant twin pairs. We identified a monozygotic twin pair with CHARGE syndrome and a de novo balanced chromosome rearrangement t(8;13)(q11.2;q22).

Methods

Fluorescence in situ hybridisation was performed with BAC and PAC probes to characterise the translocation breakpoints. The breakpoint on chromosome 8 was further refined using 10 kb probes we designed and produced using sequence data for clone RP11 33I11, the Primer3 website, and a long range PCR kit.

Results

BAC and PAC probe hybridisation redefined the breakpoints to 8q12.2 and 13q31.1. Probe RP11 33I11 spanned the breakpoint on chromosome 8. Using our 10 kb probes we demonstrated that the chromodomain gene CHD7 was disrupted by the translocation between exons 3 and 8.

Discussion

Identifying that the translocation breakpoint in our patients occurred between exons 3 and 8 of CHD7 suggests that disruption of this gene is the cause of CHARGE syndrome in the twins and independently confirms the role of CHD7 in CHARGE syndrome.     

16例平衡易位携带者的妊娠结局

作者在１９８８年１０月至１９９２年４月间对１６例非同源平衡易位携带者包括８例孕前和孕期中药治疗者的妊娠结局进行随访。结果表明，１６例共怀孕５１次，分娩健康新生儿１１名，行染色体检查的６名中，核型正常３例而与亲代相同异常者３例。本组正常妊娠率２１．５７％。这比国内其他作者报告的３．３５％增高且有显著性差异（ｐ＜０．００５）。提示中药治疗对这些携带者的正常妊娠有效。     

A fourth case of ring chromosome 7

An 8-year-old child with a ring chromosome 7 is presented, the first female and the fourth such individual to be described. The associated anomalies were rather benign: she presented with short stature, minor skeletal alterations, and normal intelligence. The only truly striking feature was the presence of multiple large, pigmented naevi, suggestive of a hamartomatous origin, but unlike those typical of any particular syndrome. Though other ring 7 patients have had naevus flammeus, and one had cafk-au-lait spots, our proband is the first with an anomaly of chromosome 7 to have such extensive lesions. These four cases of ring 7, which show great phenotypic variation, are reviewed, and the clinical presentation of the proband is also compared with that of patients suffering from terminal, interstitial and translocation-derived 7p and 7q deletions. The formation and behaviour of ring chromosomes are discussed, as are the cytogenetic factors which may influence their phenotypic expression.     

Partial trisomy of the short arm of chromosome 7 due to a familial translocation rcp(7;14) (p11;p11)

A boy with trisomy of the short arm of chromosome 7 is reported. He presented several congenital malformations, such as: dolicocephaly; wide fontanelle; hypertelorism; antimongoloid slanting of the palpebral fissures; small, carp-shaped mouth; thin neck; extrinsic compression of the oesophagus; congenital dislocation of the shoulders and hips; and a possible cardiac defect. The proband's mother had a balanced translocation involving the short arm of chromosomes 7 and 14. In this family the translocation has been transmitted through three generations.     

Unique t(Y;1)(q12;q12) reciprocal translocation with loss of the heterochromatic region of chromosome 1 in a male with azoospermia due to meiotic arrest: a case report

A de novo reciprocal translocation 46,X,t(Y;1)(q12;q12) was found in an azoospermic male with meiotic arrest. Cytogenetics and fluorescent in situ hybridization (FISH) were used to define the karyotype, translocation breakpoints and homologue pairing. SRY (Yp), Yq11.2-AZF regions, DAZ gene copies and the distal Yq12 heterochromatin were studied by PCR and restriction analysis using sequence-tagged sites and single nucleotide variants. High resolution GTL, CBL and DA-DAPI staining revealed a (Y;1) translocation in all metaphases and a normal karyotype in the patient's father. FISH showed the presence of the distal Yq12 heterochromatic region in der(1) and loss of the heterochromatic region of chromosome 1. PCR demonstrated the intactness of the Y chromosome, including the SRY locus, AZF regions, DAZ genes and distal heterochromatin. A significant decrease (P = 0.005) of Xp/Yp pairing (18.6%), as compared with controls (65.7%), was found in arrested primary spermatocytes, and cell culture and mRNA expression studies confirmed an irreversible arrest at meiosis I, with induction of apoptosis and removal of germ cells by Sertoli cells. We characterized a de novo t(Y;1)(q12;q12) balanced reciprocal translocation with loss of the heterochromatic region of chromosome 1, that caused unpairing of sex chromosomes followed by meiosis I arrest, apoptotic degeneration of germ cells and azoospermia.     

Familial 5p- syndrome

This report concerns a mother and son with a small terminal deletion of the short arm of chromosome 5 (del(5)(qter → pi5.1:). Both mother and son had superficial resemblance to patients with classical Cri-du-Chat Syndrome, but lacked the severe mental and growth retardation generally associated with such cases.     

A case of de novo i(12p) with 12q whole-arm translocation mosaicism

We report a dup(12p) due to a de novo i(12p) in a girl with mosaicism for 12q whole-arm translocations onto 7p, 7q, and 11q terminal regions. The dup(12p) syndrome was confirmed by clinical, cytogenetic, and LDH-dosage studies.     

Monosomy 10qter due to a balanced familial translocation: t(10;16)(q25.2;q24)

A third case of monosomy 10q is described. The infant was severely malformed and died at day 9 post partum. The clinical symptoms are compatible with the two previous cases.