The causal disease The idic(15) (isodicentric chromosome 15) or inv dup(15) (inverted duplicated chromosome 15) syndrome is a complex neurogenetic condition characterized by early central hypotonia, developmental delay and intellectual disability, epilepsy, and autistic or autistic-like behavior. The latter is characterized by lack of social interaction, non-functional use of objects, primordial type of exploration, stereotypies, absent or very poor echolalic language, limited comprehension, and poor intention to communicate. Physically, there are only minor anomalies (Battaglia et al. 1997; Battaglia 2005, 2008). Incidence at birth is estimated to be 1 in 30000 with a sex ratio of almost 1 (Schinzel and Niedrist 2001). However, due to dysmorphic features being absent or subtle and to the rarity of major malformations, chromosome analysis may not be thought to be indicated, and a number of individuals probably remain undiagnosed. The chromosome region 15q11–q13 is prone to genomic rearrangements, due to the presence of repeated DNA elements (Christian et al. 1999; Makoff and Flomen 2007). The rearrangements include deletions leading to either Angelman syndrome (AS) or Prader–Willi syndrome (PWS), according to parental origin (Lalande 1996); translocations; inversions; and supernumerary marker chromosomes (SMCs) formed by the inverted duplication of proximal chromosome 15. Interstitial duplications, triplications, and balanced reciprocal translocations may also occur (Browne et al. 1997). Idic(15) or inv dup(15) is the most common of the heterogeneous group of the SMCs.
|Title of host publication||The Causes of Epilepsy: Common and Uncommon Causes in Adults and Children|
|Publisher||Cambridge University Press|
|Number of pages||4|
|ISBN (Print)||9780511921001, 9780521114479|
|Publication status||Published - Jan 1 2011|
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