The life-threatening effects of Spinal Muscular Atrophy
24 April 2014 Last updated at 12:36 BST
A woman believed to be the mother of three children found dead at a south-west London home has been arrested on suspicion of murder.
The children are believed to have had a serious genetic condition, thought to be Spinal Muscular Atrophy (SMA). The circumstances of the deaths are unknown, but police have focused attention on this little known disease.
Kelly Fletcher, whose daughter Lily Mae was diagnosed with SMA, and died shortly before her second birthday, explains the condition to the Today programme's Mishal Husain.
First broadcast on BBC Radio 4's Today programme on Thursday 24 April.