Unlocking the Mystery of Pyridoxine-Nonresponsive Homocystinuria: A Comprehensive Guide
Cystathionine beta-synthase deficiency lets homocysteine accumulate; blood homocysteine and methionine levels plus CBS gene analysis point to the diagnosis.
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
Cracking the Code: Understanding and Diagnosing Genetic Factors in Perinatal HIV-1 Transmission
Maternal SDF1 genotype, minor maternal viral genotypes and CCR5 polymorphisms are tied to mother-to-child spread, and testing can flag higher-risk pregnancies.
Demystifying HIV-1: Genetic Testing for Rapid Progression to AIDS
Viral recombination and Rev- and Tat-specific CTL precursor levels are studied as markers of fast decline in HIV-1, guiding earlier therapy and treatment monitoring.
Understanding, Diagnosing, and Using Genetic Testing for Hyperphenylalaninemia, BH4-Deficient, A, Due to Partial PTS Deficiency
Too little 6-pyruvoyl-tetrahydropterin synthase limits BH4, so phenylalanine accumulates. Symptoms, biochemical testing and PTS gene analysis are explained.
Early-Onset Hypertension Worsening in Pregnancy
Starting early and worsening in pregnancy, autosomal dominant hypertension carries risks for mother and baby. Inherited factors and genetic testing are examined.
Decoding the Mysteries of Hypogonadotropic Hypogonadism 14 with Anosmia
Three KAL1 defects reported in 12 males, a SOX10 deletion with hearing loss and a PTCH1 variant all connect to this Kallmann syndrome form.
Hypogonadotropic Hypogonadism 18 with Anosmia: Genes, Tests
A form of congenital hypogonadotropic hypogonadism, HH18 brings delayed or absent puberty with loss of smell. Hormone tests, MRI and DNA analysis confirm it.
Why Anosmia Is Absent in Hypogonadotropic Hypogonadism 20
Sense of smell stays intact in this subtype, so diagnosis rests on hormone levels, brain MRI and gene testing that tells it apart from other forms.