The regulator announced in July that it had opened its inquiry the previous month on the back of concerns about FAN’s governance and financial management.
On 15 July, it appointed John Ariel and Steven Law, restructuring and recovery partners at the accountancy firm Baker Tilly, as interim managers of the charity to take control to the exclusion of its existing trustees.
FAN was registered with the commission in 2010 and had objects including the promotion of the health of neuroblastoma sufferers and the support of them and their families.
A statement issued to Third Sector by Baker Tilly said: "Since their appointment in July 2014, the interim managers have tried to run FAN as normal and to allow beneficiaries to access the funds raised by their appeals.
"As a result of their investigations into the dealings and financial position of the charity, the interim managers have now concluded that FAN can unfortunately no longer continue to trade."
A Baker Tilly spokesman said that the interim managers had no alternative but to close the charity because its financial position, combined with the difficulty in raising new funds because of reputational damage, meant that it would have become insolvent very soon.
The statement said that general purpose fundraising for the charity would cease with immediate effect, although fundraising for appeals for individual children could continue, with donations remaining ring-fenced.
The interim managers said they would work to transfer other funds not held for specific appeals to charities with similar objects.
"The interim managers have written to all those families with current appeals to inform them of the decision to close the charity, and will discuss with them the options for transferring their child’s appeal fund to another charity with similar objectives," the statement said. "All funds will remain secure, and no funds will be moved without prior consent."
The charity, based in Hunstanton, Norfolk, had income of £1.4m in the year to 31 March 2013, and employed two people, according to its accounts.