Study of Hepatic Function in Patients With Spinal and Bulbar Muscular Atrophy

Background: \- Spinal and bulbar muscular atrophy (SBMA) is an inherited disease. It causes weakness in muscles used for swallowing, breathing, and speaking. SBMA mainly affects men, but women can carry the gene for it. Researchers think there may be a link between SBMA and excess fat in the liver. Objective: \- To look for fatty liver and liver injury in people with SBMA, people with motor neuron disease, and people who carry the gene for SBMA. Eligibility: * Adults 18 years and older who have SBMA, have motor neuron disease, or are carriers of SBMA. * Healthy adult volunteers. Design: * Participants will be screened with medical history, physical exam, and blood tests. * Participants will have 1 outpatient visit of 1-2 days. Women will have a urine pregnancy test. All participants will have: * Blood tests. * Liver ultrasound. A probe is placed on the abdomen at certain locations and angles and takes pictures. The painless procedure takes 20-30 minutes. * Liver magnetic resonance imaging (MRI) scan. The MRI scanner is a metal cylinder with a magnetic field. Participants will lie on a table that slides in and out of it. They will be in the scanner for about 30 minutes. They will get earplugs for loud noises. * Some participants with abnormal liver testing will have a biopsy (small piece) of the liver taken. The biopsy site will be located with ultrasound, then cleaned and numbed. The physician will quickly pass a needle in and out of the liver while the participants holds their breath. Afterward, participants will be monitored in bed for 6 hours. * Participants may return for follow-up and another 1-2 day outpatient visit yearly for up to 2 years.