Identification of an unbalanced cryptic translocation t(9;17)(q34.3;p13.3) in a child with dysmorphic features

Abstract

We report a case of an unbalanced cryptic telomeric translocation 46,XY,der(17),t(9; 17)(q34.3;pl3.3) in a boy with dysmorphic features and developmental delay. The proband had intrauterine growth retardation, postnatal short stature, and mild microcephaly. Magnetic resonance imaging showed incomplete myelination, but no evidence of lissencephaly. Cytogenetic analysis of the proband's peripheral blood showed an abnormal 17p. Fluorescence in situ hybridisation (FISH) with a Miller-Dieker cosmid probe did not detect a deletion for that area. Further analysis with a 17p telomere specific probe identified an unbalanced telomeric translocation. The same probe was used to determine the presence ofan apparent balanced translocation t(9;17) (q34.3;p13.3) in the mother of the proband. The balanced translocation was confirmed with two cosmids that map distally on 9q34.3. Two phenotypically normal half sibs, a maternal aunt, a maternal uncle, and the maternal grandmother were found to be balanced translocation carriers as well. A subtle translocation is one mechanism that can produce an abnormal phenotype in a patient who had a normal karyotype at lower band resolution levels.

Female gamete segregation in two carriers of translocations involving 2q and 14q

“…In the literature, only two cases of translocation have been reported; one by Stoll et al (1974) and the other by Coco and Penchaszadeh (1977). But studies on spermatozoa of male carriers for translocations other than those involving 2 and 14 showed that the alternate segregation was the most frequent one, with few cases having Adjacent-I as the most frequent segregation (Estop et al, 1995). Although our numbers of PBs analysed are limited, our results differ from that study.…”

Road to a rare diagnosis: Description of novel unbalanced translocation causing partial trisomy 17p

“…It presents in a spectrum ranging from mosaics (most common), to duplications, and unbalanced translocations (as per the patient described above). Most unbalanced translocations are a result of inherited genetic material from a balanced translocation in a phenotypically normal parent, 1 , 3 , 6 and de novo occurrences have been reported 2 just the proband.…”

“…In the reported cases neurological malformations (e.g., microcephaly, ventriculomegaly, cerebellar hypoplasia, and hypoplastic cerebellar vermis), congenital heart defects, 1 pre‐ and postnatal growth retardation, 2 clinodactyly of fingers, and psychomotor and mental delays 3 , 4 are described. Prognosis remains guarded for this disorder.…”

Familial cryptic translocation with del 4q34?qter and dup 12pter?p13 in sibs with tracheal stenosis: Clinical, classical and molecular cytogenetic studies and CGH analyses from archival placental tissues evidencing tertiary trisomy 4 in one abortion specimen

“…Cryptic translocations involving small chromosome segments are frequently missed in routine cytogenetic analyses, especially in the unbalanced carrier requiring fluorescence in situ hybridization (FISH) for identification or for confirmation in cases of known familial rearrangements. Cryptic translocations have been described to cause mental retardation and minor abnormalities [Estop et al, 1995; Flint et al, 1995], to lead to defined microdeletion syndromes [Masuno et al, 1995; Reid et al, 1996] or in association with hematologic malignancies resulting in disease‐specific fusion transcripts [Berger et al, 1997; Seeger et al, 1998].…”