1. Chromosome disorders Chromosome disorders are disorders due to abnormalities in structure or number of chromosomes. STRUCTURAL CHROMOSOME ABNORMALITIES Sometimes, chromosomes break, leading to 5 types of changes in chromosome structure 1. Deletion 2. Duplication 3. Inversion 4. Translocation 5. Insertion 1. Deletion: loss of portion of one chromosome. When this chromosome is passed on to off...

Genetic aberrations are commonly seen in human preimplantation embryos. Non-disjunction and premature division of a chromosome are common in both meiosis and mitosis divisions. The expected result for meiotic aneuploidies is full aneuploidy in the later stages whereas mosaicism is the most frequent event in the cleavage and blastocyst stages. The main causes for mosaicism are post-zygotic event...

A 29 year old black female with delayed development and multiple congenital anomalies showing a duplication of 14(q31----qter) is presented. Although clinical features associated with partial duplication of the distal long arm of chromosome 14 are variable, there are some features which are distinctive of this chromosomal abnormality. The clinical findings of 14 cases with duplication distal 14...

We report on a newborn female patient with a de novo pure partial duplication of 7q. The clinical features are compared with those of 19 cases from the literature with pure partial duplication of different segments of 7q. Conventional cytogenetic investigation led to the diagnosis of duplication of bands q21.3 to q35. This was confirmed by chromosome painting and by fluorescence in situ hybridi...

The accelerated development of systemic lupus erythematosus (SLE) in male BXSB mice is associated with the genetic abnormality in its Y chromosome, designated Yaa (Y-linked autoimmune acceleration). Recently, the Yaa mutation was identified to be a translocation from the telomeric end of the X chromosome (containing the gene encoding TLR7) onto the Y chromosome. In the present study, we determi...

Clinical and electrophysiological investigations and nerve biopsies were carried out on 61 patients shown to have a chromosome 17p11.2 duplication (hereditary motor and sensory neuropathy-HMSN Ia). Of these, 50 showed a Charcot-Marie-Tooth (CMT) phenotype and eight could be classified as having the Roussy-Lévy syndrome. Of the patients with a CMT phenotype, three had associated pyramidal signs ...

In Drosophila, flies with two X chromosomes are females, with one X chromosome, males. We investigated the presence of sex determining factors on the X chromosome by constructing genotypes with one X and various X-chromosomal duplications. We found that female determining factors are not evenly distributed along the X chromosome as had been previously postulated. A distal duplication covering 3...

A 35-year-old man with infertility was referred for chromosomal analysis. In routine cytogenetic analysis, the patient was seen to have additional material of unknown origin on the terminal region of the short arm of chromosome 4. To determine the origin of the unknown material, we carried out high-resolution banding, comparative genomic hybridization (CGH), and FISH. CGH showed a gain of signa...

Charcot-Marie-Tooth disease type 1 (CMT1) or hereditary motor and sensory neuropathy type I (HMSNI) is an autosomal dominant peripheral neuropathy. In most families the disease segregates with a 1.5 Mb duplication on chromosome 17p11.2 (CMT1A). A few patients have been found with point mutations in the PMP-22 gene. In some families linkage has been found with markers located on chromosome 1q21-...