Evidence-Based Supplement & Herb Guides

Developmental Delay Genetic Test: DNA Variants, Diagnosis, and Results

Learn how developmental delay genetic testing uses microarray, exome, genome, Fragile X, and targeted tests, and how to interpret positive, negative, and uncertain results.

A developmental delay genetic test looks for DNA changes that may explain why a child is learning, moving, speaking, or developing daily-living skills later...

Dravet Syndrome Genetic Test: SCN1A Gene Mutations and Results

Understand SCN1A genetic testing for Dravet syndrome, including who should be tested, variant results, treatment implications, inheritance, mosaicism, and negative tests.

A Dravet syndrome genetic test usually looks for disease-causing variants in SCN1A, the gene most often responsible for this severe developmental and epileptic encephalopathy....

Duchenne Muscular Dystrophy Genetic Test: DMD Gene, Deletions, and Results

Understand DMD genetic testing for Duchenne muscular dystrophy, including exon deletions, duplications, sequencing, reading-frame results, treatment eligibility, and carrier risk.

A Duchenne muscular dystrophy genetic test looks for disease-causing changes in the DMD gene, which provides instructions for dystrophin, a protein that protects muscle...

Epilepsy Genetic Panel Test: Seizure Genes, Diagnosis, and Results

Learn how epilepsy genetic panel testing evaluates seizure genes, who benefits, how to interpret positive, uncertain, and negative results, and when findings can guide treatment.

An epilepsy genetic panel test analyzes many genes associated with recurrent seizures and epilepsy syndromes at the same time. It is most likely to...

Facioscapulohumeral Muscular Dystrophy Genetic Test: D4Z4 Repeat, SMCHD1, and Results

Understand FSHD genetic testing, including D4Z4 repeat size, permissive 4qA haplotypes, SMCHD1, methylation, FSHD1 versus FSHD2, mosaicism, and results.

A facioscapulohumeral muscular dystrophy genetic test evaluates a specialized DNA repeat region called D4Z4 near the end of chromosome 4 and, in selected cases,...

Fragile X Genetic Test: FMR1 CGG Repeats, Autism, and Results

Understand Fragile X FMR1 testing, CGG repeat ranges, methylation, mosaicism, autism-related features, premutation risks, AGG interruptions, and family results.

A Fragile X genetic test measures the number of CGG repeats in the FMR1 gene and usually assesses whether an expanded repeat is methylated....

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...