A complete duplication of X chromosome resulting in a tricentric isochromosome originated by centromere repositioning.

Background: Neocentromeres are rare and considered chromosomal aberrations, because a non-centromeric region evolves in an active centromere by mutation. The literature reported several structural anomalies of X chromosome and they influence the female reproductive capacity or are associated to Turner syndrome in the presence of monosomy X cell line.

Case Presentation: We report a case of chromosome X complex rearrangement found in a prenatal diagnosis.

Trisomy 12p and monosomy 4p: phenotype-genotype correlation.

4p Monosomy and 12p trisomy have been discussed and redefined along with recently reviewed chromosomal syndromes. 12p Trisomy syndrome is characterized by normal or increased birth weight, developmental delay with early hypotonia, psychomotor delay, and typical facial appearance. Most likely, the observed phenotypic variability depends on the type and extent of the associated partial monosomy.

Ophthalmic features in a dysmorphic boy with chromosome 4q deletion and duplication.

The 4q deletion syndrome shows varying phenotype, ranging from severe and complex malformations, unconformable with life, to more specific findings, as genitourinary, gastrointestinal and cardiac malformations, cleft palate,microcephaly, hypertelorism and abnormal ears and limbs. Strabismus, nystagmus, ophthalmoplegia, and optic nerve anomalies have been rarely described in literature. We report an original case of simultaneous deletion and duplication of chromosome 4q, confirmed by SNPs-array analysis of DNA, and characterized by a previously unreported association between optic nerve hypoplasia and progressive external ophthalmoplegia.

Supernumerary ring chromosome 8: clinical and molecular cytogenetic characterization in a case report.

We report on a 3-year-old male with developmental delay, autistic behavior, and minor abnormalities consistent with trisomy 8 syndrome whose cytogenetic analysis revealed mosaicism for a supernumerary ring chromosome (SRC). Fluorescence in situ hybridization (FISH) studies, using centromeric and yeast artificial chromosome (YAC) probes, were performed to characterize further the supernumerary chromosome. The ring origin has been detected from the short arm of chromosome 8, resulting in r(8)(p10p23.