Partial 18q trisomy and 18p monosomy resulting from a maternal pericentric inversion,inv(18)(p11.2q21.3)

A 7-year-old boy with dysmorphic features was found to have a recombinant chromosome 18, rec(18), resulting from meiotic recombination of a maternal pericentric inversion, inv(18) (p11.2q21.3), as defined by high-resolution banding. He was trisomic for the long arm (q21.3-qter) and monosomic for the short arm (p11.2-pter) of chromosome 18. His clinical features were compared with those in other rec(18) cases, and also those in monosomy 18p, trisomy 18qter and full trisomy 18 syndromes. The risk of recombinant formation for inv(18) carriers was also discussed.     

Familial pericentric inversion inv(8)(p23q11).

We describe two families in whom a pericentric inversion, inv(8)(p23q11), is segregating. No examples of unbalanced karyotypes were encountered. The families originated from neighbouring parishes in western Finland. In one family a mild form of mental retardation segregated. However, this phenotype did not cosegregate with the inversion karyotype. There was no evidence of a higher than average abortion rate in the inversion carriers. Carrier matings produced 19 children with a balanced inversion and 14 children with a normal karyotype, concordant with a 1:1 segregation ratio. Of 13 karyotyped men at risk, 10 were inversion carriers. However, this difference was not statistically different from the expected 1:1 ratio. In females, the inversion carrier to normal ratio was 10:11.     

Familial 10p trisomy resulting from a maternal pericentric inversion

We report a familial recombination of a pericentric inversion of chromosome 10 resulting in 2 affected relatives who had 10p trisomy and 10q monosomy with the karyotypic abnormality designated rec(10) dup p,inv(10) (p11.2q26). Both of these individuals had the typical characteristics of 10p trisomy, however, at birth the proposita had mild facial anomalies suggesting that the distinct facial characteristics may be of postnatal onset in some cases. In addition, the proposita had gastroesophageal reflux causing severe anemia. The phenotype of our patients is compared to 41 patients with 10p trisomy reported in the literature. © 1994 Wiley-Liss, Inc.     

Partial monosomy 5p and partial trisomy 5q due to paternal pericentric inversion 5(p15.1q35.1)

A male infant with karyotype 46,XY,rec(5),dup q,inv(5)(p15.1 q35.1)pat is presented. The proband showed growth and developmental retardation, complex cardiovascular abnormalities, inguinal hernia and microcephaly in addition to facial appearance and cat-like cry characteristic of the cri-du-chat syndrome. Growth and developmental retardation, and microcephaly noted in this patient were markedly more serious than those observed in patients either with partial monosomy 5p or with partial trisomy 5q alone.     

Partial monosomy 5p and partial trisomy 5q due to paternal pericentric inversion of chromosome 5

Summary A male infant with partial monosomy 5p and partial trisomy 5q due to paternal pericentric inversion of chromosome 5 (46,XY,rec(5), dup q,inv(5)(p15.1q35.1)pat) is reported together with the oral findings. The phenotype was chiefly the cri-du-chat syndrome. Severe retardation of mental and motor development, microencephaly, cardiac malformation, crying and facial appearance unique to the cri-du-chat syndrome were observed. Perioral and intraoral findings included thin upper lip, downturning corners of mouth, micrognathia, shallow palate, and cleft of soft palate. Anterior deciduous teeth were small and canine deciduous teeth were conic. The row of deciduous teeth showed a flat arch-like shape that was very wide but short in length. No abnormality was noted in the number of deciduous teeth or the timing of eruption.     

Recombinant chromosome 18 resulting from a maternal pericentric inversion

We report on a newborn girl with duplication of 18q12.2→18qter and deficiency of 18p11.2→18pter which resulted from meiotic recombination of the maternal pericentric inversion, inv(18) (p11,2q12.2). Her clinical manifestations were compatible with those of partial trisomy 18q syndrome. We review the previously reported 9 cases in 8 families of rec(18) resulting from recombination of a parental pericentric inversion. © 1994 Wiley-Liss, Inc.     

A malformed child with a recombinant chromosome 7, rec(7) dup p, derived from a maternal pericentric inversion inv(7)(p15q36).

We report a child with facial dysmorphic features, hypoplasia of the external genitalia, intestinal malrotation, congenital cardiac defect, and minor limb anomalies. Chromosome studies showed a recombinant chromosome 7, rec(7) dup p, resulting from a maternal pericentric inversion inv(7)(p15 q36). Thus, this child had partial trisomy 7p in addition to a small distal monosomy 7. The clinical findings are compared with those found in previous reports of trisomy 7p. Finally, some general principles for genetic counselling are discussed.     

Partial trisomy 22 (q11.2-q13.1) as a result of duplication and pericentric inversion.

A case of a 27 year old male with a duplication of part of the long arm of chromosome 22 (22q11.2-q13.1) together with a pericentric inversion of the same chromosome is reported. Particular phenotypic features of note include absence of speech, persistent self-injury, lack of daily living skills, colobomata, and very poor vision. Similarities between this case and other case reports of duplications of the long arm of chromosome 22 are discussed.     

Bilateral split hand/foot malformation and inv(7)(p22q21.3).

A boy with typical tetramelic split hands and feet is described. In addition, there was a large arteriovenous malformation of the right arm. Chromosome studies showed a pericentric inversion of chromosome 7: 46,XY,inv(7)(p22q21.3). Inspection of the extremities and chromosome studies in the parents were normal. This case confirms the suggested localisation of a locus, important for early limb differentiation, on the long arm of chromosome 7, most probably in the chromosomal region 7q21.2-7q21.3. Previously reported cases are reviewed briefly.     

Partial monosomy and partial trisomy 18 in two offspring of carrier of pericentric inversion of chromosome 18.

A pericentric inversion of chromosome 18 is described in the mother of a patient with clinical diagnosis of 18q--syndrome. The propositus' chromosome complement includes the recombinant 18 with deficiency of the distal one-third of the long arm and duplication of the terminal segment of the short arm. The propositus' sister carrier the recombinant 18 with a duplication of the distal one-third of the long arm and a deficiency of the terminal segment of the short arm. The relative length of the inverted segment represents about 60% of the total chromosome 18 length. The probability of recombinant formation following the occurrence of a chiasma within the inverted segment is predicted to be high.     

Rare interstitial deletion (2)(p11.2p13) in a child with pericentric inversion (2)(p11.2q13) of paternal origin

An unbalanced 46,XY,der(2)del(2)(p11.2p13) inv(2)(p11.2q13) karyotype was found in a phenotypically abnormal child with a de novo interstitial deletion of band 2p12 associated with an inv(2)(p11.2q13) inherited from the father. The inv(2) is generally considered a benign familial variant without significant reproductive consequences. However, our findings led us to consider a previously proposed mechanism of unequal meiotic crossing over at the base of a parental inversion loop, which could lead to either a deletion or duplication of a segment adjacent to the inverted region in the offspring. This phenomenon has been reported in other inversions of chromosomes 1, 7, 13, 15, and 17 and may explain the origin of the deletion in our patient. Although repetitive sequences might be present around such inversions, which could predispose to de novo deletions independently of the inversion, current evidence including this case favors a proposed causal relationship between the parental inversion and the deletion in the child. Our review and results suggest there could be a small risk for a related imbalance to couples with an inv(2)(p11.2q13). For del(2)(p11.2p13), which is rare, a more distinct phenotype has been proposed herein. Our patient shared several findings with the three previously published cases, namely the broad nasal bridge, abnormal ears, high-arched palate, psychomotor retardation, and micrognathia. However, our patient also had sensorineural hearing loss and significant hypotonia, which have not been previously reported, thereby expanding our understanding of this rare deletion. Am. J. Med. Genet. 87:139–142, 1999. Published 1999 Wiley-Liss, Inc.     

Deletion 9p, duplication 18q in two sisters resulting from a maternal (9;18) (p22;q21.3) translocation

We have studied two sisters with partial deletion 9p and partial duplication 18q resulting from adjacent 1 segregation of a maternal translocation (9;18) (p22;q21.3). The clinical manifestations identified in our patients were compared with those reported in the literature for 9p- and 18q+ patients involving approximately the same amount of genetic material. There was relatively greater similarity with the 9p- syndrome than with dup (18q) syndrome, but typical characteristics of both conditions were lacking.     

Rare interstitial deletion (2)(p11.2p13) in a child with pericentric inversion (2)(p11.2q13) of paternal origin.

An unbalanced 46,XY,der(2)del(2)(p11.2p13) inv(2)(p11.2q13) karyotype was found in a phenotypically abnormal child with a de novo interstitial deletion of band 2p12 associated with an inv(2)(p11.2q13) inherited from the father. The inv(2) is generally considered a benign familial variant without significant reproductive consequences. However, our findings led us to consider a previously proposed mechanism of unequal meiotic crossing over at the base of a parental inversion loop, which could lead to either a deletion or duplication of a segment adjacent to the inverted region in the offspring. This phenomenon has been reported in other inversions of chromosomes 1, 7, 13, 15, and 17 and may explain the origin of the deletion in our patient. Although repetitive sequences might be present around such inversions, which could predispose to de novo deletions independently of the inversion, current evidence including this case favors a proposed causal relationship between the parental inversion and the deletion in the child. Our review and results suggest there could be a small risk for a related imbalance to couples with an inv(2)(p11.2q13). For del(2)(p11.2p13), which is rare, a more distinct phenotype has been proposed herein. Our patient shared several findings with the three previously published cases, namely the broad nasal bridge, abnormal ears, high-arched palate, psychomotor retardation, and micrognathia. However, our patient also had sensorineural hearing loss and significant hypotonia, which have not been previously reported, thereby expanding our understanding of this rare deletion. Am. J. Med. Genet. 87:139-142, 1999. Published 1999 Wiley-Liss, Inc.     

Two pericentric inversions, inv(2)(p11q13) and inv(5)(p13q13), in a patient referred for psychiatric problems

Two pericentric inversions were found in the karyotype of a male patient referred for psychiatric problems. Cytogenetic analysis, using conventional Giemsa staining and G and C banding techniques, revealed a pericentric inversion in chromosome 2, inv(2)(p11q13), and chromosome 5, inv(5)(p13q13) (fig 1). Subsequent family studies showed that the proband's father carried both inversions also (fig 2), while other members were found to be carriers of either the inverted 2 or the inverted 5. To our knowledge, this is the first report of two pericentric inversions to be found in the human genome.     

Partial trisomy 18 in a family with a translocation (18;21)(q21;q22).

A family is described in which 2 sibs had similar congenital abnormalities. Chromosome investigation of the mother and another child disclosed they were carriers of a translocation t(18;21)(q21;q22). The karyotype of one of the abnormal infants was determined and was found to be consistent with partial trisomy 18,46,XY,-21,+der (21),t(18;21) ((18pter leads to 18q21::21q22 leads to 2 lqter)mat.     

Familial partial monosomy 5p and trisomy 5q; three cases due to paternal pericentric inversion 5 (p151q333)

A family is described in which the mother's 9 pregnancies ended in the birth of 2 healthy girls, 4 spontaneous abortions and 3 infants with multiple congenital malformations as bird-headed appearance, pre- and postnatal growth deficiency, microcephaly, micrognathia with small mouth and cat-like cry. Two of the three affected sibs had complex cardiac malformations incompatible with life; the third had a bicuspid aortic valve. Chromosomal investigation revealed an abnormal karyotype: 46,XX,rec(5),dupq,inv(5)(p151q333)pat, leading to a partial monosomy 5p and partial trisomy 5q. A large pericentric inversion of chromosome 5 was found in the father: 46,XY,inv(5)(p151q333) as well as in the firstborn healthy female sib. The clinical features partly fit the partial monosomy 5p as well as the partial trisomy 5q syndrome.     

Three cases of dup(10p)/del(10q) syndrome resulting from maternal pericentric inversion

Two families and 3 patients with dup(10p)/del(10q) syndrome segregating from a maternal pericentric inversion are described, including a stillborn female with Potter sequence and multicystic renal dysplasia. Comparison of 32 dup(10p) patients to 11 del(10)(q25) patients emphasized dolichocephaly, wide sutures, frontal bossing, micrognathia, and renal defects as distinguishing characteristics of the dup(10p) syndrome. The 3 new and 6 previously reported dup(10p)/del(10q) patients had several manifestations in common with the dup(10p) and del(10q) syndromes, but were more typical of dup(10p) syndromes, with respect to all 5 distinguishing characters. © 1993 Wiley-Liss, Inc.