Miscarriage, defined as spontaneous pregnancy loss at <20-28 weeks' gestation, is a common clinical problem. Balanced chromosomal rearrangements in either parent are an important cause of repeated pregnancy loss, particularly in the first trimester. In this study, chromosomal abnormalities that cause recurrent miscarriage were evaluated in Omani parents and some of their dysmorphic children. A total of 380 couples (760 individuals) with two or more recurrent miscarriages were examined for chromosomal aberrations during the period 1999-2006. For each proband the chromosomal preparations were analysed and karyotyped after applying a Giemsa-trypsin banding method. The overall incidence of chromosomal anomaly was 26 out of 760 individuals (3.42%). These abnormalities included 21 (2.8%) structural aberrations and 5 (0.7%) numerical anomalies. In addition to these abnormalities, 39 (5.1%) chromosomal variants were also found. The nature of these abnormalities and their relation to obstetric history are discussed. In conclusion, chromosomal abnormality is one of the causes of recurrent miscarriage. This study illustrates the incidence and distribution of chromosomal abnormalities among Omani couples with recurrent miscarriage. Cytogenetic findings could provide valuable information for genetic counselling and allow monitoring of future pregnancies by prenatal diagnosis in couples with a history of recurrent miscarriage.

Genetic changes associated with acute lymphoblastic leukemia (ALL) provide very important diagnostic and prognostic information with a direct impact on patient management. Detection of chromosome abnormalities by conventional cytogenetics combined with fluorescence in situ hybridization (FISH) play a very significant role in assessing risk stratification. Identification of specific chromosome abnormalities has led to the recognition of genetic subgroups based on reciprocal translocations, deletions and modal number in B or T-cell ALL. In the last twelve years 102 newly diagnosed childhood/adult ALL bone marrow samples were analysed for chromosomal abnormalities with conventional G-banding, and FISH (selected cases) using specific probes in our hospital. G-banded karyotype analysis found clonal numerical and/or structural chromosomal aberrations in 74.2% of cases. Patients with pseudodiploidy represented the most frequent group (38.7%) followed by high hyperdiploidy group (12.9%), low hyperdiploidy group (9.7%), hypodiploidy (<46) group (9.7%) and high hypertriploidy group (3.2%). The highest observed numerical chromosomal alteration was high hyperdiploidy (12.9%) with abnormal karyotypes while abnormal 12p (7.5%) was the highest observed structural abnormality followed by t(12;21)(p13.3;q22) resulting in ETV6/RUNX1 fusion (5.4%) and t(9;22)(q34.1;q11.2) resulting in BCR/ABL1 fusion (4.3%). Interestingly, we identified 16 cases with rare and complex structural aberrations. Application of the FISH technique produced major improvements in the sensitivity and accuracy of cytogenetic analysis with ALL patients. In conclusion it confirmed heterogeneity of ALL by identifying various recurrent chromosomal aberrations along with non-specific rearrangements and their association with specific immunophenotypes. This study pool is representative of paediatric/adult ALL patients in Oman.