Prenatal detection of cryptic rearrangements by multiplex ligation probe amplification in fetuses with ultrasound abnormalities.

PURPOSE: Congenital malformations are a major cause of morbidity and mortality in newborn infants, and genomic imbalances are a significant component of their etiology. The aim of this study was to evaluate the ability of prenatal multiplex ligation probe amplification screening to detect cryptic chromosomal imbalances in fetuses with ultrasound abnormalities of unknown etiology. METHODS: Multiplex ligation probe amplification was performed with three separate sets of probes: two for subtelomeric regions and one for mental retardation syndrome loci. Sixty-one fetuses with significant ultrasound anomalies and normal karyotype at a minimum of 400-band resolution were tested between January 2007 and January 2009. RESULTS: We identified four unbalanced rearrangements: one del 18pter/amp 5pter, one del 9pter, one 15q11q13 microdeletion, and one 22q11 microdeletion with atypical presentation. After genetic counseling, two of the pregnancies were terminated. CONCLUSION: Multiplex ligation probe amplification analysis was able to identify clinically significant rearrangements in 6.5% of fetuses with prenatally identified sonographic abnormalities. This prospective study highlights that multiplex ligation probe amplification screening of fetuses with ultrasound abnormalities in the prenatal period is technically feasible and relevant for diagnosis and prognosis.

Prenatal BoBsTM in the cytogenetic analysis of products of spontaneous miscarriage.

BACKGROUND: Fifty percent of spontaneous miscarriages (SMs) are attributed to chromosomal abnormalities. Cytogenetic analysis is an important tool for patient counselling and assessment of the risk of recurrence in future pregnancies. Conventional karyotyping has been the gold standard for chromosomal investigation of products of conception (POC), but it has limitations due to sample maceration, culture failure and maternal cell contamination. Molecular cytogenetic approaches have therefore been developed and found valuable in the cytogenetic investigation of these samples. The Prenatal BoBsTM and KaryoLite BoBsTM, based on the newly developed BACs-on-BeadsTM technology, have been described as reliable tests for rapid detection of aneuploidies in prenatal and POC samples, respectively. OBJECTIVE: To describe our clinical experience of routine screening of POC samples with Prenatal BoBsTM, the test used by our laboratory in France. METHODS: Seventeen samples collected at the University Hospital of Sidi Bel Abbès (Western Algeria) and a further 60 from the University Hospital of Clermont-Ferrand (France) were analysed (19 chorionic villi from products of curettage, 12 placentas, 9 amniotic cells and 37 biopsy specimens). All were screened for the frequent aneuploidies (chromosomes 13, 18, 21, X and Y) in addition to nine microdeletion/microduplication syndrome regions by Prenatal BoBsTM. Standard karyotyping was performed on 51 samples, but failed in 38 cases. RESULTS: Prenatal BoBsTM identified one trisomy 21 and one deletion of 17p13.3. Furthermore, it provided a conclusive result in cases of culture failure (n=38) and in samples with macerated tissue (n=19). The overall failure rate was 11.4%. CONCLUSIONS: Prenatal BoBsTM is a promising technology that represents a fast, sensitive and robust alternative to routine screening for chromosomal abnormality in products of SM. Furthermore, it overcomes the limitations of conventional karyotyping and current molecular cytogenetic techniques.