22q11.2 Deletion Syndrome due to a Translocation t(6;22) in a Patient Conceived via in vitro Fertilization

A Rare Case of Mosaic Unbalanced Non-Robertsonian Translocation Involving Chromosomes 15 and 22 with Congenital Abnormalities in Monozygotic Twins

Balanced de novo non-robertsonian translocations (non-RTs), which involve acrocentric chromosomes, are rare findings in clinical cytogenetics and may be associated with an abnormal phenotype. These translocations, detected by conventional karyotyping, are found in approximately 1:1,000 neonates. In most of these cases, one of the parents carries the same translocation. In this study, we report a rare non-RT involving chromosomes 15 and 22 defined as 45, XX, -22,der(15;22)t(15;22)/46, XX, der(15)t(15;22),der(22). To our knowledge, this is the first report of a non-RT t(15;22) with these breakpoints.

De novo Unbalanced 1;22 Translocation with 22q11 Deletion Syndrome

This report describes a newborn girl presenting with some of the common features of DiGeorge syndrome/velocardiofacial syndrome (DGS/VCFS), including hypocalcemia, atrial septal defect, and aortic stenosis. Several genetic tests were carried out to determine the origin of the clinical phenotype. MLPA was initially performed followed by aCGH, cytogenetic analysis, and FISH. Cytogenetic analysis of the proband's parents was also done. MLPA revealed a deletion in 22q11.1q11.2 spanning from the cat eye syndrome region to the most commonly deleted region in DGS/VCFS patients. The size of the deletion as defined by aCGH was 3.2 Mb. The karyotype of the proband was 45,XX,der(1)t(1;22)(p36.3;q11.2)dn,-22, the karyotypes of the parents were normal. FISH analysis showed that the 22q11 deletion occurred in the der(1). No loss or gain of chromosomal material was evident for chromosome 1, as confirmed by MLPA, aCGH, and FISH. Unbalanced translocations resulting in DGS are relatively rare, with limited reports in the literature. To our knowledge, this is the second case involving chromosome 1 and the first one with breakpoints in 1p36 and 22q11.2. This case also emphasizes the importance of combining diagnostic methods to better understand a given genetic abnormality.

De novo unbalanced translocation t(15;22)(q26.2;q12) with velo-cardio-facial syndrome: A case report and review of the literature

The present study reports the case of a 3-h old male with a de novo unbalanced t(15;22) translocation and velo-cardio-facial syndrome (VCFS), with other abnormalities. The manifestations of the condition observed in the patient included cleft palate with feeding difficulties, respiratory infection, dysmorphic face with almond-shaped eyes, a long and wide nose, small and low-set ears, tetralogy of Fallot, cryptorchidism and varus equinus. Standard lymphocyte cytogenetic analysis using G-banding demonstrated a 45,XY,-22,der (15),t(15;22)(q26.2;q12) karyotype. Fluorescent in situ hybridization with DiGeorge/VCFS TUPLE 1 confirmed 22q11 deletions. These cytogenetic aspects appear to be rare in the etiology of VCFS, as >1% of all 22q11 deletions are the result of an unbalanced translocation, which involves chromosomes 22 and another chromosome. To the best of our knowledge, this is the second reported case where the clinical features associated with VCFS are combined with an unbalanced (15;22) translocation involving the critical 22q11.2 region.