Leona is the apparent biological daughter of House's old friend Dylan Crandall in the episode Who's Your Daddy?. She is the granddaughter of famous jazz pianist Jesse Baker. She is portrayed by actress Aasha Davis.
Leona was in New Orleans during Hurricane Katrina and could not evacuate. Her mother died during the hurricane and lost her home. She survived on her own for eight months.
Dylan was an old friend of Dr. House and brought Leona to Princeton-Plainsboro Teaching Hospital. Dr. Cuddy did the intake and noted the patient had cardiogenic shock, but had not suffered a heart attack. Dr. Cuddy called Dr. House and when he arrived told him the patient had a full cardiac work-up and the tox screen was clean, and the blood cultures showed no infection. Dr. House met with Dylan and when he found out about the circumstances of how Dylan had just met Leona, he doubted her story that she was his daughter. He agreed to take the case anyway.
Dr. House met with his team. Dr. Chase thought it might be a myocardial infarction, but the emergency room had ruled that out. However, Dr. House ordered Dr. Chase to do the test again in the event the ER got it wrong. Dr. Cameron thought it might be Wolf-Parkinson-White syndrome, which had also been ruled out by the ER, but Dr. House ordered a re-test again. He also admonished his team for not studying the patient's medical history and chart. Dr. Foreman noted an abnormality on Leona's EKG, but Dr. House noted that overall her heart was fine. When Dr. Cameron noted that the patient had been in Katrina, Dr. House suggested that she may have gotten something from the unsanitary conditions there. Dr. House thought it might be an intermittent arythmia, but if that were the case it might not reoccur while she was in the hospital. Dr. House wanted to induce an arythmia, but Dr. Cameron noted that was dangerous given that Leona had just suffered cardiac shock. Dr. House wanted to proceed anyway and went to Dylan himself to get consent.
Dylan was worried about the procedure. Dr. House agreed it was dangerous, but told him to sign anyway. He also wanted to do a paternity test. Hoewver, Dylan refused the paternity test. He did agree to the cardiac test.
The team anethesized Leona and started inserting catheters into her heart to electrically stimulate different parts of it. During the tests, she developed a super-ventricular tachycardia and her heart rate rose to a peak of 260. Dr. House wanted to know if she was hallucinating, and Dr. Foreman reported she was not. Dr. Chase ordered an intravenous push of 12.5 adenosine. The patient's heart started to fail. However, Dr. House determined from this that the part of the heart was not the bad pathway and that she was having an ordinary heart attack. Dr. Foreman used the defibrillator and brought the patient back to normal rhythm. Dr. House wanted to proceed with the test and did so over Dr. Chase's objection. When they tested the high right atrium, the patient did have a hallucination, indicating this was the faulty heart pathway. Dr. Chase used the catheter to freeze the faulty heart muscle, destroying it and allowing the heart to beat normally. The patient's heart rhythm again returned to normal and she stopped hallucinating.
However, while Leona was resting, she heard voices and had another visual hallucination, this time of her mother. This apparently showed that her heart was not fixed, but a subsequent EKG showed it was working properly. However, Dr. House thought it might not be a hallucination, but an atypical seizure. He suggested post-traumatic stress syndrome. If it was a hallucination, that meant the heart problem was merely a coincidence. However, Dr. House suggested that perhaps the heart problem and the hallucination were simply different manifestations of the same disease. Perhaps the hallucination was set off by the pain of the arythmia. Dr. Cameron realized that several autoimmune diseases could cause those symptoms and suggested a CRP or a test of the rheumatoid factor. However, Dr. House wanted to confirm by causing Leona pain while he did a CT Scan.
They restrained Leona and put her in the CT Scan, and pricked her finger. However, her neurological response was normal and she didn't hallucinate. However, when Dr. House put her under further stress by accusing her of lying to Dylan and bending her finger backwards, she did have a hallucination. This confirmed an autoimmune disorder, but didn't narrow it down. In order to treat her, she needed a bone marrow transplant with a perfect match, but they pointed out they had no siblings. Dr. House intimated that it shouldn't be a problem if Dylan was really her father.
Dr. House went to listen to a CD of Leona's grandfather when Dylan came in and asked why Dr. House was checking the bone marrow registry instead of testing him. Dylan insisted on a bone marrow test, but still refused a paternity test. However, his marrow was not a match. Luckily, they found a match in the marrow registry. They started radiation treatment to destroy Leona's diseased marrow. However, as Dr. House and Dr. Wilson were observing the procedure, Dr. House noticed something oozing out of Leona's mouth. They immediately stopped the radiation and went to examine the patient.
The lab results confirmed Dr. House's suspicions that the material oozing from her mouth was intestinal contents. He realized this because it oozed out of her mouth instead of spewing (like vomit) or coughing. There was also digested blood in the mix, showing internal bleeding. The most likely cause was liver failure causing renal proteins to back up into her intestines, interfering with clotting and causing a blockage. The fast progression of the liver failure appeared to rule out an autoimmune disease. Dr. House wanted to do a liver biopsy.
Dr. House explained to Dylan that it wasn't an autoimmune problem and her bone marrow wasn't destroyed by the radiation, but that the reverse digestive process was very serious. Dylan consented to a liver biopsy even though there was a risk Leona could die during the procedure.
Dr. House went back to listen to the CD made by Leona's grandfather that came with Dylan's book. It was outtakes from recording sessions where he lost his temper.
Dr. Chase performed the liver biopsy, assisted by Dr. Foreman. However, just before Dr. Chase got there, Dr. House called it off and asked his team to come to listen to the CD. Leona's grandfather lost his temper about the piano being out of tune, but Dr. House noted that the notes were actually in tune. Something was affecting the grandfather's personality and aural perception. When this was combined with liver failure, Dr. Cameron realized that he could have had hemochromatosis; excess iron in his blood. Dr. Cameron went to run a TIBC and serum ferritin. However, Dr. House confirmed the diagnosis by noting that her skin color had become darker in the past three years, even though she had no tan line. He ordered a SQUID exam to test her iron levels and deferoxamine for chelation therapy. Dr. Foreman did the squid exam on the MRI and found the excess iron.
They started treatment, but all of a sudden Leona went into respiratory arrest. Dr. Chase intubated her and she was put on a respirator. A CT Scan showed that her lungs were full of holes. It is clear that the hemachromatosis diagnosis was correct, but it was just as true that the treatment nearly killed her. They discussed what chelating agents do - they essentially act as lubricants for iron stuck in the body, allowing it to move freely through the bloodstream where it can be passed through urine and feces. Dr. House realized that Leona also had issues with her digestive tract, which may mean the iron wasn't being disposed of. The iron may have went to her lungs instead, bound with whatever was in her lungs, and started making small holes. Some infections bind with iron, but Leona was put on a full course of antibiotics before the radiation. Dr. Cameron noted some neuro-degenerative diseases also like iron rich environments, but the squid exam found no iron deposits in the brain. Dr. Foreman noted that many fungi also bind to iron, and that seemed to not be ruled out by any of the tests. However, without knowing what fungus it was, there were 25 anti-fungal medications to choose from. Dr. House ordered voriconazole for aspergillis because it is the most common fungal infection.
However, Leona's lungs soon collapsed, meaning it wasn't aspergillis. They went over where Leona lived because different fungi are generally found in different places. Leona reported living in a children's shelter, but Dr. House figured she was lying about that. They couldn't ask her because she was intubated. However, Dr. House revived her and asked her to answer questions by blinking. He told her if she was lying about the children's shelter, she would die. She wroted down that she was living in the recording studio. Recording studios are full of baffles to absorb sound, but during Katrina, they would absorb huge amounts of moisture, allowing zygomycosis to thrive. Dr. House ordered amphotericin B and colony-stimulating factors to treat it. Leona was soon breathing on her own and her liver function returned to normal.
Once Leona was breathing on her own again, Dr. House informed her that he had done a paternity test and confirmed she really was Dylan's daughter. This causes Leona to break down sobbing and she is then comforted by Dylan. However, the paternity test was actually negative.