Mental retardation with 45 chromosomes 45,XX,--5,--14,+der(5) t(5,14)(p15;q13) mat due to familial balanced reciprocal translocation.

A girl with severe mental retardation and odd facies and some features of the cri-duchat syndrome was found to have only 45 chromosomes. Her karyotype was 45,XX, -5, -14,+der(5) t(5,14)(p15;q13) mat. Her mother and her two sisters were found to be balanced reciprocal translocation carriers having 46 chromosomes, one of which was a very small (14pter leads to 14q13::5p15leads to 5pter) that was missing in the proposita.     

X;14 translocation:an exception to the critical region hypothesis on the human X-chromosome

We report on a family in which an X;14 translocation has been identified. A phenotypically normal female, carrier of an apparently balanced X-autosome translocation t(X;14)(q22;q24.3) in all her cells and a small interstitial deletion of band 15q112 in some of her cells had 2 offspring. She represents a fifth case of balanced X-autosome translocation with the break point inside the postulated critical region of Xq(q13 q26) associated with fertility. The break point in this case is located in Xq22, the same band as in four previously published exceptional cases. In most of her cells, the normal X was inactivated. Her daughter, the proposita, has an unbalanced karyotype 46,X,der(X), t(X;14)(q22;q24.3)mat, del(15)(q11.1q11.3)mat. She is mildly retarded and has some Prader-Willi syndrome manifestations. She has two normal 14 chromosomes, der(X), and deletion 15q11.2. Her clinical abnormalities probably could be attributed to the deletions 15q and Xq rather than 14q duplication. In most of cells, der(X) was inactivated. We assume that spreading of inactivation was extended to the 14q segment on the derivative X. Late replication and gene dose studies support this view. Another daughter, who inherited the balanced X;14 translocation and not deletion 15 chromosome, is phenotypically normal.     

X;14 translocation: An exception to the critical region hypothesis on the human X-chromosome

We report on a family in which an X;14 translocation has been identified. A phenotypically normal female, carrier of an apparently balanced X-autosome translocation t(X;14) (q22;q24.3) in all her cells and a small interstitial deletion of band 15q 112 in some of her cells had 2 offspring. She represents a fifth case of balanced X-autosome translocation with the break point inside the postulated critical region of Xq(q13 q26) associated with fertility. The break point in this case is located in Xq22, the same band as in four previously published exceptional cases. In most of her cells, the normal X was inactivated. Her daughter, the proposita, has an unbalanced karyotype 46,X,der(X), t(X;14)(q22;q24.3)mat, del(15)(q11.1q11.3)mat. She is mildly retarded and has some Prader-Willi syndrome manifestations. She has two normal 14 chromosomes, der(X), and deletion 15q11.2. Her clinical abnormalities probably could be attributed to the deletions 15q and Xq rather than 14q duplication. In most of cells, der(X) was inactivated. We assume that spreading of inactivation was extended to the 14q segment on the derivative X. Late replication and gene dose studies support this view. Another daughter, who inherited the balanced X;14 translocation and not deletion 15 chromosome, is phenotypically normal.     

Maternal translocation (9;18) with two abnormal offspring each with different chromosome derivatives.

We report a phenotypically normal woman with an apparently balanced reciprocal translocation between chromosomes 9 and 18 [46,XX,t(9;18)(p22;p11.2)], giving rise to unbalanced chromosome complements in two of her children, each of whom received a different derivative chromosome. The proband's karyotype is 46,XY,-18,+der(18), t(9;18)(p22;p11.2)mat, which results in a duplication of the distal portion of the short arm of chromosome 9 with a concomitant deletion of much of the short arm of chromosome 18. The karyotype of the proband's brother is 46, XY,-9,+der(9),t(9;18)(p22;p11.2)mat, which results in a deletion of the distal short arm of chromosome 9 and a duplication of most of the short arm of chromosome 18. The phenotype of each child is significantly different from that of his sib and is not consistent with any previously reported chromosome abnormality.     

Recurrent spontaneous abortions due to a homologous Robertsonian translocation (14q14q)

A female with a history of recurrent spontaneous abortions was shown to carry a balanced Robertsonian translocation involving the No 14 homologues. One abortus had trisomy 14 with a 46,XX,-14,+t(14q14q)mat karyotype.     

Balanced complex rearrangement involving chromosomes 8, 9, and 12 in a normal mother,derivative chromosome 9 with recombinant chromosome 12 in her daughter with minor anomalies

We report on a 19-month-old girl with a derivative chromosome 9 and a recombinant chromosome 12 resulting from a maternal balanced complex rearrangement involving chromosomes 8, 9, and 12. The karyotype of the phenotypically normal mother was 46,XX,t(8;12) (9;12) (8qter→8p23::12q12→12q15::9q32→9qter;9pter→9q32::12q15→12qter;12pter→12q12::8p23→8pter). The child's karyotype was 46,XX,?9,?12, +der(9) (9pter→9q32::12q15→12qter),+rec(12) (12pter→12q15::9q32→9qter) mat. The child had severe growth retardation, minor anomalies including trigonocephaly, hypertelorism, broad nasal root, apparently low-set and posteriorly angulated ears, triangular face, pectus carinatum, clinodactyly of fifth fingers, and almost normal psychomotor development. To the best of our knowledge, there have been only 3 previous reports of recombination derived from parental complex chromosome rearrangements. In the recombination products, the chromosomes were apparently balanced and the offspring had no clinical abnormalities. The present case exhibited abnormalities and may have a submicroscopic aberration of 12q arising from crossing over during maternal meiotic pairing, although her chromosomes appeared to be balanced. © 1993 Wiley-Liss, Inc.     

"Masked" Ph1 chromosome in a complex three-way translocation

A patient with myelofibrosis was found to have a 46,XX,del(1)(q24),del(11)(p11),-22,+mar karyotype in unstimulated peripheral blood (PB) and spleen cells. On detailed cytogenetic examination it was determined that this patient had an apparently "masked" Ph1 chromosome contained in a complex three-way translocation. Since phytohemagglutinin (PHA)-stimulated PB and spleen cells were essentially normal, the masked Ph1 chromosome was assumed to be an acquired cytogenetic abnormality. The portion missing from the masked Ph1 chromosome was apparently translocated onto del(1). Thus, the detailed karyotype was 46,XX,t(1;11;22)(q24;p11;q11 or q12),t(1;22)(q24;q11 or q12). This complex rearrangement was present primarily in cells belonging to the granulocyte-macrophage cell lineage, whereas E-rosetting cells, and presumably T lymphocytes, had normal karyotypes.     

Familial complex chromosome rearrangement giving rise to balanced and unbalanced recombination products

We report on a family ascertained through a 14-month-old girl with a terminal deletion of chromosome 8p23.1. Analysis of the karyotype of other relatives showed that the mother is the carrier of a balanced complex 4-break chromosome rearrangement, which she and her brother inherited from their father following recombination. This complex chromosome rearrangement (CCR) was confirmed by fluorescence in-situ hybridization (FISH) using libraries for chromosomes 1, 8, and 9, and telomeric probes for the long arm of chromosome 9. The karyotype of the maternal grandfather was 46,XY,t(1;8) (p31;q21.1),t(8;9)(p23.1;q34). The karyotype of his daughter is 46,XX,rec(8)t(1;8) (p31;q21.1)t(8;9)(p23.1;q34)pat. The karyotype of the proposita is 46,XX,rec(8)t(8;9) (p23.1;q34)mat, and that of her abnormal elder sister is 46,XX,t(1;8)(p31;q21.1)rec(8) t(8;9)(p23.1;q34)mat,der(9)t(8;9)(p23.1;q34) mat. Unbalanced segregation and/or recombination during maternal meiosis gave rise to the two abnormal sisters, one effectively with 8p trisomy and the other with monosomy for that same 8p segment. To our knowledge, this is the first case of a familial CCR giving rise to unbalanced recombination products. Am. J. Med. Genet. 79:30–34, 1998. © 1998 Wiley-Liss, Inc.     

47,XX,+der(18),t(9;18)(p24;q21) mat: a distinct partial trisomy 18q--syndrome?

A moderately retarded girl had a 47,XX,+der(18),t(9;18)(p24;q21)mat abnormality that was inherited from her mother, who had a 46,XX,t(9;18)(p24;q21) karyotype in most cells, and a minor cell line of 47,XX,+der(18),-t(9;18)(p24;q21). Her dysmorphic features--bilateral epicanthic folds, low-set, abnormal ears, low posterior hairline, clinodactyly of the 5th fingers, and broad great toes--were similar to those of other patients with an additional number 18 chromosome in which all or most of the long arm was missing, thus raising the possibility of a distinct syndrome.     

Familial 5/14 translocation with triple X and 47,XY + 14q-

A family with 5/14 balanced translocation was investigated. The father and both his daughters had the same balanced translocation. One of the daughters had four spontaneous abortions, the last one with a karyotype of 47,XY + 14q –. The other daughter had two children, one of them a normal 46,XX girl, the other with the karyotype 47,XXX;t5/14.     

Trisomy 16q arising from a maternal 15p;16q translocation.

Trisomy 16q is reported in a malformed infant who died at 12 days of age. The karyotype was 46,XX,der(15)t(15;16) (p11;q11)mat. A balanced translocation was found in the mother. The consequences of various types of aneuploidy of chromosome 16 are discussed.     

Reproductive risk in mating between two translocation carriers: Case report and review of the literature

We conducted a study to determine the reproductive risk in a couple who were translocation carriers. This couple, who carried balanced reciprocal translocations, experienced habitual abortions. The wife had a karyotype of 46,XX,t(7;13)(p15.3;q12.3) and the husband of 46,XY,t(1;7)(p11.1;p11.1). Chromosome study of their fourth abortus demonstrated a chimera consisting of two cell lines with a 46,XY and a 46,XX,t(1;7)(p11.1;p11.1)pat, ?13, +der(7)t(7;13)(15.3;q12.3)mat, karyotype. A review of the literature indicates that the risk of having unbalanced live offspring or of spontaneous abortion/stillborns is similar in couples in whom both were translocation carriers and in couples in whom one individual was a translocation carrier. The apparent lack of increased reproductive failure may result from the selective disadvantage of aneusomic gametes at fertilization or very early spontaneous abortions of unbalanced conceptuses. © 1993 Wiley-Liss, Inc.     

Identification of cryptic imbalance in phenotypically normal and abnormal translocation carriers

Approximately one in 500 individuals carries a reciprocal translocation. Of the 121 monosomy 1p36 subjects ascertained by our laboratory, three independent cases involved unbalanced translocations of 1p and 9q, all of which were designated t(1;9)(p36.3;q34). These derivative chromosomes were inherited from balanced translocation carrier parents. To understand better the causes and consequences of chromosome breakage and rearrangement in the human genome, we characterized each derivative chromosome at the DNA sequence level and identified the junctions between 1p36 and 9q34. The breakpoint regions were unique in all individuals. Insertions and duplications were identified in two balanced translocation carrier parents and their unbalanced offspring. Sequence analyses revealed that the translocation breakpoints disrupted genes. This study demonstrates that apparently balanced reciprocal translocations in phenotypically normal carriers may have cryptic imbalance at the breakpoints. Because disrupted genes were identified in the phenotypically normal translocation carriers, caution should be exercised when interpreting data on phenotypically abnormal carriers with apparently balanced rearrangements that disrupt putative candidate genes.     

Familial reciprocal translocation t(7;16) associated with maternal uniparental disomy 7 in a Silver‐Russell patient

We present the case of a maternal heterodisomy for chromosome 7 in the daughter of a t(7;16)(q21;q24) reciprocal translocation carrier. The proband was referred to the hospital for growth retardation and minor facial dysmorphism without mental retardation. A diagnosis of Silver‐Russell syndrome was suspected. Chromosomal analysis documented a 46,XX,t(7;16)(q21;q24)mat chromosome pattern. Microsatellite analysis showed a normal biparental inheritance of chromosome 16 but a maternal heterodisomy of chromosome 7. Occurrence of uniparental disomy (UPD) is a well‐recognized consequence of chromosomal abnormalities that increase the rate of meiotic nondisjunction, mainly Robertsonian translocations and supernumerary chromosomes. Although reciprocal translocations should, theoretically, be also at increased risk of UPD, only three cases have been reported so far. However, because the association between uniparental disomy and reciprocal translocation may exist with an underestimated frequency, prenatal diagnosis is recommended when clinically relevant chromosomes for UPD are involved. © 2002 Wiley‐Liss, Inc.     

Familial reciprocal translocation t(7;16) associated with maternal uniparental disomy 7 in a Silver-Russell patient

We present the case of a maternal heterodisomy for chromosome 7 in the daughter of a t(7;16)(q21;q24) reciprocal translocation carrier. The proband was referred to the hospital for growth retardation and minor facial dysmorphism without mental retardation. A diagnosis of Silver-Russell syndrome was suspected. Chromosomal analysis documented a 46,XX,t(7;16)(q21;q24)mat chromosome pattern. Microsatellite analysis showed a normal biparental inheritance of chromosome 16 but a maternal heterodisomy of chromosome 7. Occurrence of uniparental disomy (UPD) is a well-recognized consequence of chromosomal abnormalities that increase the rate of meiotic nondisjunction, mainly Robertsonian translocations and supernumerary chromosomes. Although reciprocal translocations should, theoretically, be also at increased risk of UPD, only three cases have been reported so far. However, because the association between uniparental disomy and reciprocal translocation may exist with an underestimated frequency, prenatal diagnosis is recommended when clinically relevant chromosomes for UPD are involved.     

Familial translocation t(9;16).

We report a female with a deletion of 9p and concomitant duplication of 16q [46,XX,-9,+der(9),t(9;16)(p24;q13)]. Parental chromosome analysis showed a balanced maternal translocation [46,XX,t(9;16)(p24;q13)]. Three other cases of translocations involving chromosomes 9 and 16 have been reported, one of them with identical breakpoints. A review of published reports of deletion 9p and duplication 16q is presented, and a comparison is made with previously described cases.     

Multiple apparently unrelated clonal chromosome abnormalities in a squamous cell carcinoma of the tongue

We have cytogenetically examined short-term cultures from a squamous cell carcinoma of the tongue, a tumor type in which chromosome aberrations hitherto have not been reported. No less than 12 pseudodiploid clones were detected, giving the tumor karyotype 46,X,der(X)t(X;1)(q26;p32),der(1)(Xqter→Xq26::1p32→cen→1q42:),del(13)(q11q21),t(15;?) (q26;?)/46,XX,t(1;?)(p34;?),inv(2)(p21q11)/46,XX,t(1;10)(p32;q24)/46,XX,+der(1)(12pter→ 12p11::1p11→cen→1q32::11q13→11q32→1q42:),del(11)(q13q22), - 12, der(17)t(1:17) (q42;p13)/46,XX,inv(1)(p22q44)/47,XX,del(1)(q32),der(17)t(1:17)(p22;q25),der(1)inv(1) (q25q44)t(1;17)(p22;q25),ins(14;7)(q11;q22q36), + 14/46,XX,t(1;4)(q23;q35)/46,XX,t(1;21) (q25;q22),t(2;10)(q31;q26),t(22;?)(q12;?)/46,XX,del(1)(q32)/46,XX,t(1;8)(q44;q21)/46,XX, t(2;21)(q11;p11)/46,XX,t(9;11)(q34;q13). The large number of apparently unrelated abnormalities leads us to suggest that the carcinoma may have been of multiclonal origin.     

Trisomy 18q: 46, XX,13q+,t(13;18)(q32;q11) in a newborn associated with multiple congenital anomalies due to paternal reciprocal translocation, 46, XY,-13,+der(13)/t(13;18)(q32;q11)

A 20-day-old female neonate presented with multiple congenital anomalies, convulsions and failure to thrive. Karyotype analysis of the proposita revealed an unbalanced translocation, 46, XX,13q+,t(13;18)(q32;qll)pat resulting in partial trisomy 18q. Her father and a 5-year-old sister were phenotypically normal, balanced translocation carriers, 46, XY, -13, + der(13),t(13;18)(q32;qll) and 46, XX,-13,+der(13),t(13;18)(q32;qll), respectively. The case presented here is the second liveborn reported with trisomy 18q and is of interest from the point of view of the structural chromosomal aberration resulting in the manifestations of most features of trisomy 18 and some of 13q monosomy. The infant died due to convulsions at the age of 2 months.     

Complex chromosome rearrangement and recombinant balanced translocation in a mother and a daughter with the same phenotypic abnormalities

We report on the diagnosis of a complex chromosome rearrangement in a mother and the transmission of a simplified translocation in her fetus. The mother had mental retardation, short stature, facial dysmorphism, and hydronephrosis, but was never investigated before she was pregnant. A blood sample was taken for karyotyping at the time of amniocentesis for advanced maternal age. The mother's karyotype revealed two translocations involving chromosome 5, chromosome 16 twice, and chromosome 20 as follow: 46,XX,t(5;16;20)(5pter-->5q11.2::16q12.1-->16q23::20p11.2-->20pter;16pter-->16q12.1::5q11.2-->5qter;16qter-->16q23::20p11.2-->20qter). The amniocentesis revealed a female karyotype with an apparently balanced translocation: 46,XX,t(16;20)(q23;p11.2). The translocation of the fetus probably resulted from a meiotic recombination between the derived 5 and the normal 16 in the mother. The baby was born and presented the same facial dysmorphism and hydronephrosis. The simplification of a complex rearrangement through recombination into a balanced product has only been rarely described and it is to our knowledge the first time that both the carrier of the complex rearrangement and her descendant with a simplified rearrangement share phenotypic abnormalities.