AP4-Related Intellectual Disability and Spastic Paraplegia: Unraveling the Genetic Threads
Mutations in AP4B1, AP4E1, AP4M1 or AP4S1 disrupt protein trafficking inside cells, producing intellectual disability with progressive lower-limb stiffness.
Brandon Colby, MD
MD · MBA
Physician specializing in genetic analysis and personalized preventive medicine, and author of Outsmart Your Genes.
About Brandon
Brandon Colby is a physician-expert in the fields of genetic analysis and Personalized Preventive Medicine. He holds an MD from the Mount Sinai School of Medicine, an MBA from Stanford University's Graduate School of Business, and a degree in Genetics from the University of Michigan.
Dr. Colby is the author of the book Outsmart Your Genes and has developed numerous technologies that improve the analysis, interpretation, and actionability of genome sequencing data. He is an Affiliate Specialist of the American College of Medical Genetics and Genomics (ACMG), an Associate of the American College of Preventive Medicine (ACPM), and a member of the National Society of Genetic Counselors (NSGC).
Education
- BA in Genetics with Honors, University of Michigan · 2000
- MD, Mount Sinai School of Medicine · 2004
- MBA, Stanford University Graduate School of Business · 2007
Affiliations & Memberships
- Affiliate Specialist, American College of Medical Genetics and Genomics (ACMG)
- Associate, American College of Preventive Medicine (ACPM)
- Member, National Society of Genetic Counselors (NSGC)
Articles by Brandon Colby, MD are reviewed for accuracy by Sequencing's medical and scientific team. This page is for informational purposes and does not constitute medical advice.
Articles by Brandon
Arrhythmogenic Right Ventricular Cardiomyopathy: Unraveling the Mysteries with Genetic Testing
PKP2, DSP and DSC2 variants sit behind this autosomal dominant condition, in which fatty and fibrous tissue replaces right ventricular muscle and causes arrhythmias.
Arthrogryposis with Renal Dysfunction and Cholestasis Syndrome: Genetic Testing's Role in Diagnosis and Management
Jaundice from cholestasis, kidney tubule problems and joint contractures together suggest ARC syndrome; VPS33B or VIPAR testing separates it from biliary atresia.
Astrocytoma, Anaplastic: Navigating the Genetic Landscape of a Complex Condition
Grade III tumors arising from astrocytes cause headaches, seizures and neurological deficits, and IDH1 mutation status affects prognosis and therapy choice.
ATR-X-Related Syndrome: ATRX Gene and Key Features
Intellectual disability, distinctive facial features, urogenital abnormalities and gastrointestinal dysmotility follow ATRX mutations, which testing can identify.
aHUS: What Genetic Testing Shows About Prognosis
Mutations in complement pathway genes, including an X-linked C1GALT1C1 variant, are described for aHUS, along with what they mean for therapy and family planning.
Advancements in Atypical Rett Syndrome: The Role of Genetic Testing
Broader symptoms than classic Rett syndrome, and both sexes can be affected. MECP2, CDKL5 and FOXG1 tests may come back negative, so MRI can add structural findings.
Charcot-Marie-Tooth Disease Type 2M: Genes and Testing
Muscle weakness and wasting in the arms and legs follow damage to peripheral nerves. One copy of the altered gene is enough to cause CMT2M, which shapes counseling.