Hi all,

I have this exel file with two columns A (ID) and B (Gene): 
ID             Gene

hsa-let-7a	KRAS
hsa-let-7a	HMGA2
hsa-let-7a	integrin beta(3)
hsa-let-7a	caspase-3
hsa-let-7a	PRDM1/Blimp-1
hsa-let-7a	HMGA2
hsa-let-7a	IGF-II
hsa-let-7a	HMGA2
hsa-let-7a	HMGA2
hsa-let-7a	RAS
hsa-let-7a	BCL2
hsa-let-7a	RAS
hsa-let-7a	MYC
hsa-let-7a	CDC25A
hsa-let-7a	CDK6
hsa-let-7a	NF2
hsa-let-7a	c-myc
hsa-let-7a	RAS
hsa-let-7a	RAS
hsa-let-7a	NIRF
hsa-let-7b	Cdc34
hsa-let-7b	Dicer
hsa-let-7b	KRAS
hsa-let-7b	CCND1
hsa-let-7b	CDC25A
hsa-let-7b	CDK6
hsa-let-7b	HMGA2
hsa-let-7c	HMGA2
hsa-let-7c	HMGA2
hsa-let-7c	HMGA2
hsa-let-7c	BCL2
hsa-let-7c	RAS
hsa-let-7c	CDC25A
hsa-let-7c	CDK6
hsa-let-7c	RAS
hsa-let-7d	KRAS
hsa-let-7d	HMGA2
hsa-let-7d	BCL2
hsa-let-7d	RAS
hsa-let-7d	CDC25A
hsa-let-7d	CDK6
hsa-let-7d 	BDNF
hsa-let-7d 	D3R
hsa-let-7e	HMGA2
hsa-let-7g	KRAS
hsa-let-7g	HMGA2
hsa-let-7g	Ras
hsa-let-7g	HMGA2
hsa-let-7g	CDC25A
hsa-let-7g	CDK6
hsa-miR-1	c-Met
hsa-miR-1	calmodulin
hsa-miR-1	Gata4
hsa-miR-1	Mef2a
hsa-miR-1	BCL2
hsa-miR-1	Gata4
hsa-miR-1	calmodulin
hsa-miR-1	Mef2a
hsa-miR-1	C/EBPa
hsa-miR-1	FoxP1
hsa-miR-1	HDAC4
hsa-miR-1	MET
hsa-miR-1	HCN4
hsa-miR-1	FoxP1
hsa-miR-1	HDAC4
hsa-miR-1	MET
hsa-miR-1	Cdk9
hsa-miR-1	fibronectin
hsa-miR-1	RasGAP
hsa-miR-1	Rheb
hsa-miR-1	MEF-2
hsa-miR-1	nAChR
hsa-miR-1	GAJ1
hsa-miR-1	KCNJ2
hsa-miR-1	HSP60
hsa-miR-1	HSP70
hsa-miR-1	Hand2
hsa-miR-1	Kir2.1
hsa-miR-100	Plk1
......
(line cut)
I would like to have for column A a single entry and in column B the respective associated name comma separated, like that:

ID                     Gene
  
hsa-let-7a    KRAS,HMGA2,integrin beta(3),caspase-3,PRDM1/Blimp-1,HMGA2,IGF-II,HMGA2,HMGA2,RAS,BCL2,RAS,MYC,CDC25A,CDK6,NF2,c-myc,RAS,RAS,NIRF
hsa-let-7b    Cdc34,Dicer,KRAS,CCND1,CDC25A,CDK6,HMGA2
hsa-let-7c    HMGA2,HMGA2,HMGA2,BCL2,RAS,CDC25A,CDK6,RAS
.........
Do you know any way to do that automatically?

Thanks in advance,
Giorgio