title: Small supernumerary marker chromosomes and their correlation with specific syndromes.
abstract: A small supernumerary marker chromosome (sSMC) is a structurally abnormal chromosome. It is an additional chromosome smaller than one chromosome most often lacking a distinct banding pattern and is rarely identifiable by conventional banding cytogenetic analysis. The origin and composition of an sSMC is recognizable by molecular cytogenetic analysis. These sSMCs are seen in different shapes, including the ring, centric minute, and inverted duplication shapes. The effects of sSMCs on the phenotype depend on factors such as size, genetic content, and the level of the mosaicism. The presence of an sSMC causes partial tris- or tetrasomy, and 70% of the sSMC carriers are clinically normal, while 30% are abnormal in some way. In 70% of the cases the sSMC is de novo, in 20% it is inherited from the mother, and in 10% it is inherited from the father. An sSMC can be causative for specific syndromes such as Emanuel, Pallister-Killian, or cat eye syndromes. There may be more specific sSMC-related syndromes, which may be identified by further investigation. These 10 syndromes can be useful for genetic counseling after further study.
authors: Cellular and Molecular Research Center, Medical Faculty, Shahrekord University of Medical Sciences, Shahrekord, Iran.
authors: Hamideh
authors: H
authors: Jafari-Ghahfarokhi
authors: Cellular and Molecular Research Center, Medical Faculty, Shahrekord University of Medical Sciences, Shahrekord, Iran.
authors: Maryam
authors: M
authors: Moradi-Chaleshtori
authors: Institute of Human Genetics and Anthropology, Jena University Hospital, Jena, Thuringia, Germany.
authors: Thomas
authors: T
authors: Liehr
authors: Cellular and Molecular Research Center, Medical Faculty, Shahrekord University of Medical Sciences, Shahrekord, Iran.
authors: Morteza
authors: M
authors: Hashemzadeh-Chaleshtori
authors: Cellular and Molecular Research Center, Medical Faculty, Shahrekord University of Medical Sciences, Shahrekord, Iran.
authors: Hossein
authors: H
authors: Teimori
authors: Cellular and Molecular Research Center, Medical Faculty, Shahrekord University of Medical Sciences, Shahrekord, Iran.
authors: Payam
authors: P
authors: Ghasemi-Dehkordi
keywords: Banding cytogenetic; fluorescence in situ hybridization; small supernumerary marker chromosome; syndromes