A 7 year old Texas girl suffering from a rare disease received a heart transplant on Monday, more than eight months after she and her 9 year old sister were put on the transplant list because of the same rare ailment.

Emily Smith, 7, and her sister Shayde Smith, 9, both suffer from a rare condition called restrictive cardiomyopathy in which the heart doesn’t relax between pumps and doesn’t fill properly with blood and this can cause blood clots or death. There is no known cause for the ailment and although it seems to run in families, but the condition hasn't yet been proven to be genetic.

Dr. Kristine Guleserian, the pediatric cardiothoracic surgeon who led the team operating on Emily at Children's Medical Center Dallas said the condition is rare and diagnosed in less than one-in-a-million children. The chances of survival without a transplant are 40-50% one to two years after diagnosis.

As Emily had more symptoms, including wheezing spells and her lips, toes and fingertips turning blue when she got cold, she was put on higher priority for a transplant than her sister Shayde. "My Grandma asked me if I had a heart, and I said no, and then she told me that Emily had a heart", says Shayde. "We were really wanting her to get her transplant because she is much worse than me. So I am so happy," she says.

Their mother Natalie Van Noy said, Shayde was happy her sister Emily had received a transplant. "She's still nervous about it, but she said that now that Emily's made it through, she knows she will."

The transplant operation took five hours. Dr. Kristine Guleserian, who performed the transplant, said, "We are very happy and just so thrilled to see these beautiful girls on their way to recovery." Emily's father says it is a relief to have a heart for one of his daughters, but still waits for the other. "We still have a long road ahead", says Matt Smith.

Pam Silvestri, a spokeswoman for Southwest Transplant Alliance, one of the organ donation agencies across the country that provides organs to transplant hospitals said although it’s not rare for siblings to need transplants it is rare that they need them at the same time.  Doctors say it is critical for anyone with this heart disease to receive a transplant and said it's hard to tell how long Shayde may wait for a heart.

Emily's Grandfather Mark Smith thanked the donor family for what he called a selfless gift. "I know that family has suffered a huge loss, and for us it is the happiest of days," he said.

As per official records, Children's Medical Center has performed 100 transplants till October 2007.