Evidence-Based Supplement & Herb Guides

Friedreich Ataxia Genetic Test: FXN Gene, GAA Repeats, and Results

Understand Friedreich ataxia genetic testing, FXN GAA repeat ranges, positive and carrier results, inheritance, limitations, and follow-up care.

Friedreich ataxia genetic testing looks for disease-causing changes in the FXN gene, most often an abnormal expansion of a GAA DNA repeat. The test...

Frontotemporal Dementia Genetic Test: MAPT, GRN, C9orf72, and Results

Learn how MAPT, GRN, and C9orf72 testing is used in frontotemporal dementia, what positive or uncertain results mean, and how relatives are affected.

Frontotemporal dementia genetic testing looks for inherited causes of progressive changes in behavior, personality, language, executive function, or movement. The three most common genes...

GBA Genetic Test: Parkinson Disease Risk, Gaucher Disease, and Results

Understand GBA genetic testing for Parkinson disease risk and Gaucher disease, including methods, variant results, inheritance, limitations, and follow-up.

A GBA genetic test looks for changes in the GBA1 gene, which provides instructions for the lysosomal enzyme glucocerebrosidase. The same gene can be...

Hereditary Ataxia Genetic Test: Spinocerebellar Ataxia Genes and Results

Learn how hereditary ataxia genetic testing detects SCA genes and repeat expansions, what positive, negative, and uncertain results mean, and when broader testing helps.

A hereditary ataxia genetic test searches for inherited DNA changes that can cause poor balance, unsteady walking, slurred speech, abnormal eye movements, limb incoordination,...

Hereditary Spastic Paraplegia Genetic Test: Spasticity Genes and Results

Understand hereditary spastic paraplegia genetic testing, including common HSP genes, panel and genome methods, result meanings, inheritance, mimics, and follow-up.

A hereditary spastic paraplegia genetic test looks for DNA variants that cause progressive stiffness and weakness of the legs. Hereditary spastic paraplegia, or HSP,...

Huntington Disease Genetic Test: HTT CAG Repeats, Risk, and Results

Learn how the Huntington disease genetic test measures HTT CAG repeats, what each result range means, and how predictive testing, inheritance, and follow-up work.

A Huntington disease genetic test counts a repeated DNA sequence called CAG in the HTT gene. The result can confirm Huntington disease in someone...

Intellectual Disability Genetic Test: Chromosomal Microarray, Exome Sequencing, and Results

Understand genetic testing for intellectual disability, including chromosomal microarray, exome sequencing, result types, limitations, and next steps.

Genetic testing for intellectual disability is not one test. It is a coordinated evaluation that may include chromosomal microarray, exome or genome sequencing, and...

Limb-Girdle Muscular Dystrophy Genetic Test: Muscle Disease Genes and Results

Learn how limb-girdle muscular dystrophy genetic testing evaluates muscle disease genes, interprets results, distinguishes mimics, and guides care.

A limb-girdle muscular dystrophy genetic test looks for inherited causes of progressive weakness around the hips and shoulders. “Limb-girdle muscular dystrophy,” or LGMD, is...

LRRK2 Genetic Test: Parkinson Disease Risk and Results

Understand LRRK2 genetic testing for Parkinson disease, including pathogenic variants, penetrance, family risk, uncertain results, and clinical next steps.

An LRRK2 genetic test looks for variants in one gene that can substantially increase the chance of Parkinson disease. The most widely recognized variant...

Malignant Hyperthermia Genetic Test: RYR1, CACNA1S, Anesthesia Risk, and Results

Learn how malignant hyperthermia genetic testing evaluates RYR1 and CACNA1S, what results mean, why negative tests can miss risk, and how to plan safe anesthesia.

A malignant hyperthermia genetic test looks mainly for pathogenic variants in RYR1 and, less often, CACNA1S or STAC3. These genes control calcium movement in...

Myotonic Dystrophy Genetic Test: DMPK, CNBP Repeat Expansions, and Results

Learn how DMPK and CNBP repeat-expansion tests diagnose myotonic dystrophy types 1 and 2, explain result ranges, inheritance, limitations, and medical follow-up.

A myotonic dystrophy genetic test measures unstable DNA repeat expansions that cause myotonic dystrophy type 1 or type 2. Type 1, or DM1, results...

Neurologic Genetic Panel Test: Brain, Nerve, Muscle Genes, and Results

Understand how neurologic genetic panels test brain, nerve, and muscle genes, what positive, VUS, carrier, and negative results mean, and when other tests are needed.

A neurologic genetic panel is a group of genes analyzed together to look for an inherited cause of symptoms involving the brain, spinal cord,...

Parkinson Disease Genetic Test: LRRK2, GBA, SNCA, PRKN, and Results

Learn how LRRK2, GBA1, SNCA, PRKN, PINK1, PARK7, and VPS35 testing is interpreted in Parkinson disease, including positive, carrier, VUS, and negative results.

Parkinson disease genetic testing looks for inherited variants that can cause Parkinson disease, raise susceptibility, or explain unusually early symptoms. The most commonly tested...

Polygenic Risk Score (PRS) for Alzheimer Disease: Genetic Risk and Results

Learn what an Alzheimer disease polygenic risk score measures, how APOE and ancestry affect results, why percentiles are not probabilities, and where clinical limits remain.

An Alzheimer disease polygenic risk score combines information from many common DNA variants into one statistical estimate of genetic susceptibility. It is not a...

Prader-Willi Syndrome Genetic Test: Methylation, Deletion, UPD, and Results

Learn how methylation, chromosomal microarray, maternal UPD testing, and imprinting-center analysis diagnose Prader-Willi syndrome and clarify recurrence risk.

Prader-Willi syndrome testing looks for loss of activity from paternally expressed genes in chromosome region 15q11.2-q13. The recommended first step is usually DNA methylation...

Psychiatric Pharmacogenetic Test: Depression, Anxiety, Medication Response, and Results

Learn what psychiatric pharmacogenetic tests can reveal about CYP2D6, CYP2C19, and antidepressant metabolism, why color bins have limits, and how to use results safely.

A psychiatric pharmacogenetic test examines inherited variants that may affect how the body processes certain medications. For depression and anxiety treatment, the most useful...

Rett Syndrome Genetic Test: MECP2 Gene Mutations and Results

Learn how MECP2 sequencing, deletion testing, mosaicism, and result categories support a Rett syndrome diagnosis, family counseling, and care planning.

A Rett syndrome genetic test looks mainly for disease-causing changes in MECP2, a gene on the X chromosome that helps regulate how nerve cells...

Spinal Muscular Atrophy (SMA) Genetic Test: SMN1, SMN2 Copy Number, and Results

Understand SMA genetic testing, including SMN1 and SMN2 copy number, silent-carrier risk, newborn screening, diagnostic results, and family next steps.

A spinal muscular atrophy genetic test usually measures copies of SMN1, the gene whose loss causes most 5q SMA, and SMN2, a closely related...

Spinocerebellar Ataxia Genetic Test: CAG Repeat Expansions and Results

Learn how spinocerebellar ataxia CAG repeat testing works, what repeat ranges mean, why assay methods matter, and how results guide care and families.

A spinocerebellar ataxia CAG repeat test measures repeated CAG DNA units in specific genes associated with inherited ataxia. Common targets include ATXN1, ATXN2, ATXN3,...

Cell-Free DNA (cfDNA) Test: Prenatal Screening, Cancer, and Transplant Results

Learn how cell-free DNA testing is used for prenatal screening, cancer mutation analysis, and transplant monitoring, including result meanings, limitations, and follow-up.

A cell-free DNA test analyzes short DNA fragments that circulate outside cells, most often in blood plasma. The same basic specimen can answer very...