Chromosomal imbalance letterTrisomy of chromosome 16p13.3 due to an unbalanced insertional translocation into chromosome 22p13
Section snippets
Array CGH
Giemsa-banded karyotypes at an 800 band-level obtained from PHA stimulated lymphocyte cultures from the patient and both parents were normal. FISH analysis for deletions of chromosome 22q11 and all subtelomeres was normal as well as the screening of selective exons in the ATRX gene. Array CGH was performed [5].
Chromosomal anomaly
A de novo insertional translocation of chromosome 16p13.3 into the short arm of chromosome 22 was present (Fig. 2, Fig. 3). The minimal size of the insertion is 4.5 Mb, the maximal size 7 Mb (flanking clones within the duplication region are RP11-433P17 at 3.4 Mb and RP11-148F10 at 7.9 Mb).
The karyotype is 46,XY, ish der(22),ins(22;16)(p13;p13.3p13.3) de novo.
This karyotype was confirmed by FISH and also to be de novo as both parents had no translocations.
Clinical description
The maternal serum screening for chromosomal anomalies carried out at 15 weeks gestation in the first and spontaneous pregnancy of a non-consanguineous couple indicated an increased risk of 1 in 72 for trisomy 18. Echography at 16 weeks gestation indicated mild polyhydramnios, marked foetal ascites, an enlarged liver, clubbed feet, relatively short femora, a relatively large biparietal diameter and a thick placenta. A normal male karyotype 46,XY was found on amniocentesis.
Delivery occurred at
Discussion
Pure interstitial trisomy 16p13.3 has only twice previously been reported. A patient with an insertional duplication of 16p–16q, and a familial case resulting from paternal transmission of a chromosome with an ins(1;16)(q42;p13.1p13.3) have been reported [2]. Non-detection in the case reported here was possibly because the resolution of traditional karyotyping could not discriminate between a terminal duplication and duplication at 2 Mb from the telomere. Also, the insertion into the satellites
References (5)
- et al.
A case of insertional translocation resulting in partial trisomy 16p
Ann. Genet.
(2000) - et al.
Chondroplasia punctata in an infant with duplication 16p due to a 7:16 translocation
Am. J. Med. Genet.
(1985)