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.     

t(1;18)(q32.1;q22.1) associated with genitourinary malformations

We report a male infant who has impaired penile development, hypospadias, and mild developmental delay with a 46,XY,t(1;18)(q32.1;q22.1) karyotype. Fluorescent in situ hybridization (FISH) was performed to more precisely map the translocation breakpoint. The translocation breakpoint maps to a region that has been implicated in genitourinary malformations in the 18q- syndrome. This case report suggests that a gene involved in genitourinary development maps at or near the chromosome 18 translocation breakpoint.     

A case of Prader – Willi syndrome arising as a result of familial unbalanced translocation t(11;15)(q25;q13)

We report on a case of Prader-Willi syndrome (PWS) with a true reciprocal unbalanced translocation, 45,XX,-15,der(11)t(11;15)pat. The proposita was diagnosed clinically as having severe PWS. Molecular studies revealed loss of the paternal methylation pattern at locus D15S63 and a deletion encompassing the loci from at least D15S10 to D15S97 of paternal chromosome 15. FISH studies confirmed the deletion of 15q11-q13 region and the presence of two telomeres on all chromosomes. The proposita's father, the father's sister and their mother are all carriers of the same balanced translocation t(11;15)(q25;q13). By genomic imprinting we would expect that if the father's sister were to give birth to a child with the same unbalanced translocation as the proband, it would be affected by Angelman syndrome.
To date, a similar familial unbalanced translocation due to loss of the small chromosome 15 derivative has not been described.     

Inheritance and phenotypic expression of a t(7;9)(q36;q34)mat

We describe a subtle familial chromosome rearrangement which involves 7q36 and 9q34. The clinical manifestations of 3 apparently balanced individuals with presumed identical translocation breakpoints are presented. In addition, the phenotypes of 2 cytogenetically unbalanced sibs in the same nuclear family are compared.     

Mother to son transmission of del(1) (q42.1q42.3)

Familial transmission of cytogenetically visible autosome deletions is rare in humans. We describe here a case of mother to son transmission of an interstitial deletion of the distal long arm of chromosome one, breakpoints q42.1q42.3. This is the smallest described deletion of this region to date. © 2001 Wiley‐Liss, Inc.     

Tentative assignment of a locus for Rubinstein-Taybi syndrome to 16p13.3 by a de novo reciprocal translocation,t(7;16)(q34;p13.3)

During a systematic chromosomal survey of 7 unrelated patients with Rubinstein-Taybisyndrome, an apparently balanced de novo reciprocal translocation, t(7;16)(q34;p13.3), was detected in an affected boy. The involvement of the region 16p13.3 coincides with the position of one of the breakpoints in another de novo reciprocal translocation associated with Rubinstein-Taybi syndrome, suggesting that a locus for this syndrome maps to 16p13.3. © 1992 Wiley-Liss, Inc.     

Segregation of a familial balanced (12;10) insertion resulting in dup(10)(q21.2q22.1) and del(10)(q21.2q22.1) in first cousins

An interchromosomal insertion in 3 generations of a family was ascertained through two developmentally delayed first cousins. Cytogenetic analysis using G-banding and chromosome painting showed an apparently balanced direct insertion of chromosome 10 material into chromosome 12, ins(12;10)(q15;q21.2q22.1), in the mothers and grandfather of these children. The proposita inherited only the derivative 10 chromosome, resulting in deletion of 10q21.2 → 22.1 while her cousin inherited only the derivative 12, resulting in duplication of 10q21.2 → 22.1. A comparison of the proposita with published deletion cases suggests a pattern of anomalies attributable to deletion of the 10q21 → q22 region: developmental delay, hypotonia, a heart murmur, telecanthus, broad nasal root and ear abnormalities. This is the first report of a nontandem duplication of the 10q21 → q22 region. The phenotype of the cousin with the duplication does not overlap greatly with published tandem 10q duplications. Finally, this report reaffirms the importance of obtaining family studies of patients with interstitial chromosomal abnormalities. Am J. Med. Genet. 69:188–193, 1997. © 1997 Wiley-Liss, Inc.     

Lung hypoplasia in a patient with del(2)(q33‐q35) demonstrated by chromosome microdissection

We report on a 17‐month‐old girl with multiple malformations, including lung hypoplasia, multiple ventricular septal defects, craniofacial anomalies, and malrotation of the intestine. Moreover, the patient showed Robin sequence, developmental delay, as well as pre‐ and postnatal growth retardation. Postnatal cytogenetic analysis revealed an interstitial deletion on the long arm of chromosome 2. Microdissection and reverse chromosome painting of the aberrant chromosome 2 as well as FISH with a panel of chromosome 2q band‐specific YACs mapped the deletion to 2q33‐q35. Lung hypoplasia has not been described so far in patients with del(2)(q33‐q35). A review of previously reported patients showed variable phenotypes apparently due to different deleted chromosomal segments. Am. J. Med. Genet. 94:184–188, 2000. © 2000 Wiley‐Liss, Inc.     

Analysis of human sperm chromosome complements from a male heterozygous for a reciprocal translocation t(11;22)(q23;q11)

A reciprocal translocation between chromosomes 11 and 22 (t(11;22)(q23;q11)) is a site-specific translocation that is of particular interest because of the propensity for 3:1 segregation of the chromosomes during meiosis. There have been no published reports of chromosomally unbalanced offspring born as a result of adjacent 1 or 2 meiotic segregations in a heterozygote for this translocation. This could be explained by a meiotic mechanism which produces only 3:1 chromosomal segregations or by differential embryonic survival in which 2:2 adjacent segregations do not produce a viable pregnancy. To distinguish between these two possibilities, sperm chromosome complements from a man heterozygous for this 11;22 translocation were studied. The human sperm chromosomes were analysed after fertilization of zona pellucida-free golden hamster eggs. All possible 2:2 (alternate, adjacent 1, adjacent 2) and 3:1 segregations were observed and these segregations occurred in approximately equal frequencies. The frequency of other chromosome abnormalities, unrelated to the translocation, did not appear to be increased. These results indicate that the 11;22 translocation does not specifically cause 3:1 disjunction of chromosomes but that this segregation of chromosomes is more likely to result in a viable pregnancy.     

Trisomy 16p in a liveborn offspring due to maternal translocation t(16;21)(q11;p11) and review of the literature

We report on a case of dup(16p) and review previous cases. The triplicated chromosome region leading to this specific syndrome lies in 16p13.1 p13.3. Most of the cases are inherited and the mode of segregation was found to be 3:1 in half of the cases, but these observations might be due to biases. The other chromosomes involved in the translocations as well as the breakpoints in these chromosomes do not appear to be random. © 1992 Wiley-Liss, Inc.     

Rubinstein‐Taybi syndrome caused by a de novo reciprocal translocation t(2;16)(q36.3;p13.3)

Rubinstein‐Taybi syndrome (RTS) is a multiple congenital anomalies and mental retardation syndrome characterized by facial abnormalities, broad thumbs, and broad big toes. We have shown previously that disruption of the human CREB‐binding protein (CBP) gene, either by gross chromosomal rearrangements or by point mutations, leads to RTS. Translocations and inversions involving chromosome band 16p13.3 form the minority of CBP mutations, whereas microdeletions occur more frequently (∼10%). Breakpoints of six translocations and inversions in RTS patients described thus far were found clustered in a 13‐kb intronic region at the 5′ end of the CBP gene and could theoretically only result in proteins containing the extreme N‐terminal region of CBP. In contrast, in one patient with a translocation t(2;16)(q36.3;p13.3) we show by using fiber FISH and Southern blot analysis that the chromosome 16 breakpoint lies about 100 kb downstream of this breakpoint cluster. In this patient, Western blot analysis of extracts prepared from lymphoblasts showed both a normal and an abnormal shorter protein lacking the C‐terminal domain, indicating expression of both the normal and the mutant allele. The results suggest that the loss of C‐terminal domains of CBP is sufficient to cause RTS. Furthermore, these data indicate the potential utility of Western blot analysis as an inexpensive and fast approach for screening RTS mutations. Am. J. Med. Genet. 92:47–52, 2000. © 2000 Wiley‐Liss, Inc.     

Familial translocation t(10;14) (q26.1;q32.3): report of three offspring with 10q deletion and 14q duplication

We describe two brothers and a cousin with common clinical features, including mild mental retardation, motor delays, hypotonia with truncal ataxia, esotropia, and mild facial and hand dysmorphia. The initial routine chromosome study failed to detect any abnormality in the proband. Based on a high index of clinical suspicion, high-resolution chromosome studies were performed on the proband's parents. A small reciprocal translocation t(10;14) (q26.1;q32.3) was detected in the father. The breakpoint on the derivative chromosome 14 was further placed telomeric to the immunoglobulin heavy-chain gene cluster at the band q32.33 by fluorescence in situ hybridization. Studies of the proband and two affected paternal cousins revealed that each had inherited the same derivative chromosome 10 from their carrier parents. This unbalanced karyotype resulted from an adjacent-1 segregation of the 10;14 translocation.     

5-azacytidine treatments in the characterization of a t(1;21)(q12;q22) carrier karyotype

A 46,XX,t(1;21)(q12;q22) carrier was ascertained because of two abortions. The non-reciprocal nature of the rearrangement was demonstrated in 5-azacytidine treated preparations with highly decondensed and somatically paired heterochromatic regions.     

Interstitial deletion of the long arm of chromosome 4, del(4)(q28→q31.3)

Interstitial deletions of the long arm of chromosome 4 are rare. Different breakpoints are involved. Only one of the patients had a very similar deletion to that of the present case. Both had low birth weight at term; weight, length and head circumference less than the third centile; epicanthic folds; apparently low-set abnormal ears; broad nasal bridge; micrognathia; hypoplastic nails; delayed psychomotor development; and mild mental retardation. © 1995 Wiley-Liss, Inc.     

Del(14)(q22.1q23.2) in a patient with anophthalmia and pituitary hypoplasia

Only few cases with an interstitial deletion of chromosome 14 have been described so far. We report on a 21-month-old girl with an interstitial deletion of the long arm of chromosome 14, del(14)(q22.1q23.2). She presented with bilateral anophthalmia, absent left external auditory canal, facial asymmetry, microretrognathia, hypotonia, and psychomotor retardation. Skeletal X-rays showed lambdoid craniosynostosis, a very small sella turcica and cervical vertebral anomalies. Brain MRI showed the absence of the optic chiasm, an hypoplastic pituitary gland, and cortical atrophy. No cardiac or abdominal malformations were found. Two other patients with a similar deletion, (del(14)(q22.1q23) and del(14)(q22.1q22.3)), are described. Both presented with bilateral anophthalmia and absent pituitary or hypogonadism. These three cases suggest that the region 14q22 is important for eye and pituitary development. Interestingly, the human BMP-4 gene, a member of the TGF-β superfamily, maps to 14q22-q23 and may play a role in pituitary and eye development. Am. J. Med. Genet. 77:162–165, 1998. © 1998 Wiley-Liss, Inc.