Frequency of translocation down syndrome in northern Pakistan

To determine the proportion of Translocation-Down syndrome in patients of Down syndrome. Cross sectional study carried out at Armed Forces Institute of Pathology, Rawalpindi from October 2000 to October 2002. One hundred and sixty nine clinically suspected patients of Down syndrome were referred to AFIP Rawalpindi for cytogenetic confirmation during the period of study. Five ml of venous blood was collected from each case in heparinised vaccutainer tube. Blood was cultured in RPMI-1640 medium enriched with L-glutamine and foetal bovine serum. Phytohaemagglutin was used as T-cell mitogen. The cultures were incubated for 72 hours at 370C. Mitoses were arrested in metaphase by colchicine. The cells were harvested and slides prepared and aged. These were digested with trypsin and stained with Giemsa stain. Twenty metaphases were analysed under the microscope and the observations were recorded. Out of 169 patients studied, Down syndrome was confirmed in 138 [81.7%] patients on chromosomal analysis. One hundred and thirty [94.2%] of these had classical Down syndrome with 47 chromosomes [Trisomy 21]. Seven [5.1%] patients had translocation variant of Down syndrome while there was one [0.7%] case of mosaic Down syndrome. The chromosomes involved in translocation were 13, 14, 15 and 21. All of these patients had the phenotype of Down syndrome. In patients with translocation variant parents were also studied. Only one mother had the same translocation as that of her child and her age was 29 years. Our results show that 5.1% of patients with Down syndrome phenotype have the translocation variant on cytogenetic studies. Chromosomal abnormality, however, is not commonly present in the parents. Identification of this variant is more demanding and requires thorough, meticulous examination by an experienced observer as the total number of chromosomes is 46 in contrast to 47 in the classical Down syndrome

Cytogenetic study of benign mesenchymal neoplasias

Três leiomiomas uterinos humanos foram cultivados e analisados citogeneticamente. Embora o número modal estivesse na regiäo diplóide, todas as neoplasias apresentaram hiperdiploidia. Um dos casos apresentou 27% das células na regiäo hipertriplóide-hipertraplóide. As alteraçöes numéricas mais frequentes foram monossomias envolvendo os cromossomos 20 (3 casos) e 2, 7, 18 (2 casos cada) e um caso apresentou polissomias de todos os cromossomos (variando de trissomia a pentassomia). Um caso apresentou um grande anel cromossômico semelhante ao cromossomo 1 e um marcador com o rearranjo: t(2;12) (2qter - 2q14-15 - 12 pter). O significado das alteraçöes citogenéticas em tumores benignos ainda está por ser determinada

Cytogenetic studies of some species complexes of Anopheles in Thailand and Southeast Asia.

Recent studies on cytogenetics, behavioral, geographical and distinct morphological characters on adult, pupal and larval stages have revealed that "balabacensis" is a species complex. Anopheles dirus the mainland species, is distributed widely in Thailand and is renowned for its role as primary vector of human malarial parasites. Further, evidence from cytogenetic and taxonomic studies suggests that "An. dirus" is a species complex comprising at least four distinct species provisionally designated: dirus A, B, C and D. These cryptic species are distinguishable only partially morphologically, but can be separated on the basis of metaphase chromosomes using the Giemsa and Hoechst 33258 staining techniques. Apparently, these siblings show distinct patterns of geographic distribution in Thailand and Peninsular Malaysia. The recognition of dirus as a complex of species in Thailand and Peninsular Malaysia requires a re-evaluation of the role that the individual members of this complex have in the transmission of malaria parasites in this region. Cytological analysis of gene rearrangements in ovarian polytene chromosomes has shown that An. maculatus is a sibling-species complex consisting of at least four species in Thailand provisionally designated: maculatus A, B, C and G. These siblings are sympatric in some populations. Furthermore, species B is so highly polymorphic for chromosome rearrangements that four geographic forms can be recognized. It is not known whether these four forms are subspecies or yet further species within the species B complex. These sibling-species must be differentiated in order to understand any differential capabilities in their transmission of human malaria parasites. Anopheles nivipes was elevated from synonymy under An. philippinensis to full species status by Reid, a decision recently confirmed by cross mating experiments. The Thailand Malaria Division does not differentiate these two species and only identifies An. philippinensis, yet, An. nivipes is by far the most common of the two species in Thailand. Furthermore, preliminary surveys of the ovarian polytene chromosomes of several widely separated populations of An. nivipes in Thailand have revealed at least two distinct chromosomal types of nivipes based on fixed inversions on the X chromosomes.