The detailed entries of the Imprinted Gene Catalogue database were created by Benjamin Tycko, Columbia University, New York and are updated by Ian Morison


 

Detailed entry for Gene:

Kvlqt1-as
Lit1
Kcnq1ot1
(KvDMR1 CpG island)

Chromosome:

Human Chr11p15.5
Mouse Chr7 (distal)

Links:

OMIM

Imprinting:

The maternal allele of LIT1 is silent; paternal allele active in humans and mice (Lee MP et al, 1999; Smilinich NJ et al, 1999). The LIT1 RNA arises from the KvDMR1 CpG island, located in an intron of the human KvLQT1/KCNQ1 gene, and an orthologous transcript arises from an intronic CpG island of the murine Kcnq1 locus (Engemann S et al, 2000).

Gene Product:

LIT1 encodes a non-translated RNA that initiates from KvDMR1 and is transcribed in the antisense orientation to the Kvlqt1/Kcnq1 (coding) mRNA. Expressed sequence tags (ESTs) define the LIT1 RNA; the RNA may be a long primary transcript collinear with the DNA sequence (Smilinich NJ et al, 1999; Engemann S et al, 2000) and there is no evidence for splicing to a discrete size.

Functional Data:

Based on a deletion engineered by homologous recombination in somatic cells, the KvDMR1 CpG island appears to function as an imprinting control element (Horike S et al, 2000). Evidence for this possibility also comes from studies of Beckwith-Wiedemann syndrome (BWS), in which a subset of cases show loss of DNA methylation at KvDMR1 (Smilinich NJ et al, 1999). This may be linked to down-regulation of p57KIP2 and/or loss of imprinting of IGF2 (Lee MP et al, 1999; Smilinich NJ et al, 1999; Horike S et al, 2000). KvDMR1 has therefore been proposed as a second "imprinting center" on human Chr11p15.5/murine distal Chr7, somewhat analogous to the differentially methylated region upstream of H19.

 

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