Continuing role for classical cytogenetics: Case report of a boy with ring syndrome caused by complete ring chromosome 4 and review of literature.

Constitutional ring chromosomes can be found for all human chromosomes and are very rare chromosomal abnormalities. A complete ring chromosome without loss of genetic material results from fusion of subtelomeric regions or telomere-telomere fusion. In cases of complete ring chromosome, an increased incidence of severe growth failure with no or only minor anomalies has been observed and attributed to ring syndrome.

Interstitial deletion del(10)(q25.2q25.3 approximately 26.11)--case report and review of the literature.

Objectives: To present the clinical, cytogenetic, and molecular cytogenetic findings of prenatally diagnosed interstitial deletion 10q25.2-q26.1.

Duplications and copy number variants of 8p23.1 are cytogenetically indistinguishable but distinct at the molecular level.

It has been proposed that duplications of 8p23.1 are either euchromatic variants of the 8p23.1 defensin domain with no phenotypic consequences or true duplications associated with developmental delay and heart defects.