Mosaic telomeric (2;14) association in a child with motor delay

Abstract

In a 6-year-old girl referred because of mild motor delay and hyperextensible joints, chromosome analysis disclosed a derivative chromosome consisting of end-to-end fusion of chromosomes 2 and 14. Two cell lines existed in which this telomere association was present, one with a 45,XX,tas(2;14)(q37;p11) karyotype and one with a 45,XX,tas(2;14) (q37;q32) karyotype. The cell line with the telomeric fusion of 2q and 14p was present in 90% of the cells; a telomeric fusion of 2q and 14q was seen in the remaining 10% of the cells. In both association complexes, only the centromere of chromosome 14 was active. Fluorescence in situ hybridization with telomere and subtelomere probes disclosed no deletion of chromosomal material. Microsatellite analysis showed that the patient had a normal biparental contribution of chromosomes 14.

Constitutional telomeric association (Y;7) in a patient with a female phenotype

“…TAs have been mostly reported in various leukemias and solid tumors (renal tumor, squamous cell carcinoma, cardiac myxoma, giant cell tumor of bone) and exceptionally in constitutional cells. To our knowledge, only seven patients from five different families carrying a constitutional TAs with TTAGGG telomeric sequences at the junction of the TAs have been previously published [Sawyer et al, ; Engelen et al, ; Zneimer et al, ; Huang et al, ; Josifova et al, ] (Table ). We did not include the rare cases for which the presence of telomeric sequences at the junction of the TA was not proven experimentally.…”

“…The patients were healthy with normal intelligence, except two of them. A 6‐year‐old girl presented with mild learning disability [Engelen et al, ] and a de novo tas(2;14) without loss of chromosomal material in the derivative chromosome. The authors concluded that the chromosome abnormality likely did not explain the learning disability of the patient.…”

“…Interestingly, a patient with two different TAs on lymphocytes has been reported [Engelen et al, ]. This patient had one cell line with 46,XX,tas(2;14)(q37;p11) karyotype (present in 90% of the cells) and a second cell line with a 46,XX,tas(2;14)(q37;q32) karyotype (present in the remaining 10% of the cells).…”

“…In contrast, constitutional TAs are rare events. To our knowledge, five different constitutional TAs have been reported to date [Sawyer et al, ; Engelen et al, ; Zneimer et al, ; Huang et al, ; Josifova et al, ], among them two involved the Y chromosome [Sawyer et al, ; Huang et al, ]. We report on a 6‐year‐old girl for whom a monosomy X was diagnosed during pregnancy.…”

Unique mosaicism of structural chromosomal rearrangement: Is chromosome 18 preferentially involved?

“…We have found 14 published cases involving chromosome 18; this chromosome appears to be most frequently involved in these structural rearrangements (Table II). As far as we know, only a few articles describe cases involving other chromosomes (chromosome 2 [Wyandt et al, 1982], chromosomes 2 and 14 [Engelen et al, 2000], chromosome 4 [Pescia et al, 1982; Smeets et al, 1998; Doco‐Fenzy et al, 1999; Schinzel, 2000; Syrrou et al, 2001], chromosome 5 [Perfumo et al, 2000], chromosome 8 [Van Balcom et al, 1992], chromosome 9 [Leung and Rudd, 1988], chromosome 11 [Pettenati et al, 1993; Tharapel et al, 1999], chromosome 13 [Fryns et al, 1979; Jalal et al, 1990; Duckett et al, 1992], chromosome 17 [Scriven and Docherty, 1992], and X chromosome [Pettenati et al, 1993]). The general “gene poverty” of chromosome 18 [International Human Genome Sequencing Consortium, 2001] could explain why this chromosome appears to be most frequently involved in structural rearrangement mosaicisms that are compatible with life.…”