Complex neurodevelopmental disorders, such as schizophrenia, autism, attention deficit (hyperactivity) disorder, (manic) depressive illness and addiction, are thought to result from an interaction between genetic and environmental factors. Association studies on candidate genes and genome-wide linkage analyses have identified many susceptibility chromosomal regions and genes, but considerable e...

We report a female child with tetrasomy of the 15q11-q13 chromosomal region, and autistic disorder associated with mental retardation, developmental problems and behavioral disorders. Combining classical and molecular cytogenetic approaches by fluorescence in situ hybridization technique, the karyotype was demonstrated as 47,XX,+mar.ish der(15)(D15Z1++,D15S11++,GABRB3++,PML-). Duplication of th...

Isodicentric chromosome 15 [idic(15)] is a rare chromosomal abnormality that occurs due to inverted duplication of chromosome 15q. It is associated with many clinical findings such as early central hypotonia, developmental delay, cognitive dysfunction, autism spectrum disorders, and seizure. Delayed development is a common problem referred to pediatric rehabilitation clinics. A 9-month-old boy ...

Genomic imprinting appears to be a ubiquitous process in mammals involving many chromosome segments whose affects are dependent on their parental origin. One of the challenges for clinical geneticists is to determine which disorders are manifesting imprinting effects and which families are affected. Re-evaluation of cases of chromosomal abnormalities and family histories of disease manifestatio...

Chromosomal aberration is a phenomenon occurring relatively commonly in the development process. Chromosomal aberration is known to have various causes, and its frequency has been reported to vary particularly according to maternal age. Though different among reports, the frequency was around 0.6-0.8% in analysis with all childbirths1 and around 2-3% in case childbirths were reclassified based ...

Many cancer cells exhibit an unstable genome resulting from chromosomal aberrations and gene mutations in somatic cells which generate heterogeneous cell populations manifesting diseases such as cancer. Genomic/chromosomal instability can arise from non-repaired broken DNA along the chromosome or from loss of telomeric ends of chromosomes. Normally, DNA single or double-stranded breaks are repa...

In chronic lymphocytic leukaemia the majority of circulating lymphocytes which responded to phytohaemagglutinin in vitro were found to have normal karyotypes. A minor population of cells in patients treated with chemotherapy had an increased number of chromosomal rearrangements as compared with cells from normal controls and untreated patients with chronic lymphocytic leukaemia. Probably bonema...

ALTHOUGH attempts at establishing the human chromosome number dates from early in this century, it was not until 1957 when improvements in techniques became available that human cytogenetics became established as a laboratory discipline. Since 1959, many clinical disorders ranging from abnormalities of sexual, physical and intellectual development, pregnancy wastage, leukaemia and tumours, have...

Mitochondrial disorders have the highest incidence among congenital metabolic disorders characterized by biochemical respiratory chain complex deficiencies. It occurs at a rate of 1 in 5,000 births, and has phenotypic and genetic heterogeneity. Mutations in about 1,500 nuclear encoded mitochondrial proteins may cause mitochondrial dysfunction of energy production and mitochondrial disorders. Mo...