Subject: 	Comment to the FlyBase
I observed that a 160 bp sequence is repeated 250-500 bp 5' and/or 3' of the coding sequences of each of the RAB gtpase paralogs RabX2, Rab9D, CG9807, CG32670, CG32671 and CG32673. This sequence starts 460 bp 3' of the Rab9D gene, and it is present 30 bp 3' of CG9806, a gene adjacent to CG9807. Interestingly, large fractions of this sequence are relatively well conserved at more than 350 sites throughout the X chromosome, whereas the sequence is very rare on the autosomes (only 14 copies). Moreover, the 15 repeats that share more than 90% identities with the copy present 3' of Rab9D are all clustered around the six above Rab gtpase paralogs, between 9C and 9F cytological bands. The possibility that the repeat influences chromatin structure is worth considering, as it may for instance behave as a chromatin domains insulator.
Pierre Hutter, PhD, FAMH
Chef de la Division de Génétique Médicale
Institut Central des Hôpitaux Valaisans
Av. Grand-Champsec 86
1951 Sion, Switzerland