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Intrachromosomal triplication 12p11.22–p12.3 and gonadal mosaicism of partial tetrasomy 12p , **
Author(s) -
Eckel Heike,
Wimmer Rainer,
Volleth Marianne,
Jakubiczka Sibylle,
Muschke Petra,
Wieacker Peter
Publication year - 2006
Publication title -
american journal of medical genetics part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.064
H-Index - 112
eISSN - 1552-4833
pISSN - 1552-4825
DOI - 10.1002/ajmg.a.31237
Subject(s) - tetrasomy , biology , genetics , fluorescence in situ hybridization , aneuploidy , isochromosome , chromosome 12 , chromosome , karyotype , gene
Cases of tetrasomy 12p and trisomy 12p are known to be associated with specific phenotypic abnormalities well described in the literature. Here, we report on the unusual case of a partial tetrasomy 12p found in an affected patient and in a mosaic constellation in the patient's mother, who showed no phenotypic abnormality. The index patient was a 16‐year‐old boy with clinical features similar to the “trisomy 12p syndrome” including mental retardation, macrocephaly, a short nose with anteverted nostrils, and a broad protruding lower lip. G‐banding analysis and fluorescence in situ hybridization (FISH) experiments using locus specific YAC DNA probes revealed a derivative chromosome 12 with a partial triplication of the short arm with an inverted copy, flanked by two direct copies. Chromosome analyses in parental lymphocytes showed a chromosomal mosaicism in the phenotypically normal mother, with 12% cells exhibiting the same partial tetrasomy 12p as detected in her son. The allelic pattern of short tandem repeats (STR) in the mother's blood DNA showed that a chimerism can be excluded with high probability. To our knowledge, this is the first report of intrachromosomal triplication on chromosome 12, as well as partial tetrasomy 12p mosaicism. Moreover, as a consequence of the chromosomal aberration in the son it can be concluded that a gonadal mosaicism is present in the mother. © 2006 Wiley‐Liss, Inc.