Clinical Genetics Primer is an independent educational reference on the genetic basis of inherited conditions. We write for two audiences at once: families who have just heard a genetic term for the first time, and the clinicians, nurses, and allied health providers who refer those families onward. Our goal is plain clinical language, not simplification that loses accuracy.
Genetics touches an unusually wide range of medicine, from skin and hair conditions present at birth to seizure disorders that surface in early childhood. What connects them is not how they look, but how they are inherited and which gene or genes are involved. That shared biology is what this site organizes around.
Content on this site is medically informed by current genetics literature and reviewed against our own editorial standards before publication, which you can read about on our editorial standards page. We update and add pages over time as our coverage grows, and we correct anything we get wrong once we learn about it.
What makes a condition genetic
Every cell in the body carries DNA, organized into genes, that provides instructions for building and maintaining tissue. A gene variant (sometimes still called a mutation) is a change in that DNA sequence. Not every variant causes a problem. Many are harmless differences that make each person's genome unique. A variant becomes clinically significant when it changes how a gene's protein product is made or how well it works, which can alter development or function in ways that produce a recognizable condition.
Variants reach a child through a handful of well-described patterns. Some are inherited from one or both parents according to predictable rules, such as autosomal dominant or autosomal recessive inheritance. Others arise as a de novo variant, a new change that was not present in either parent's own genome. In practice, knowing the inheritance pattern matters as much to a family as knowing the diagnosis itself, because it shapes questions about recurrence risk and about testing other relatives.
This is also where the two main clusters of conditions on this site diverge in presentation while sharing the same underlying logic. We group them by biological system because that is how clinicians typically approach evaluation and referral.
Inherited skin and ectodermal conditions
The ectodermal dysplasia cluster covers a group of conditions affecting structures that develop from the ectoderm, the outer layer of the early embryo. This includes skin, hair, nails, teeth, and sweat glands. These conditions are often recognized in infancy or early childhood through a combination of features rather than any single sign, and care usually involves more than one specialist working together over time. A dentist, dermatologist, and primary care provider may each play a role, which is why coordinated, multidisciplinary follow-up tends to matter more here than a single clinic visit.
Neurogenetic conditions
The Angelman syndrome cluster covers neurogenetic conditions, where a gene variant affects brain development or function. These conditions can involve developmental delay, seizures, or movement differences, and they are frequently identified through a combination of clinical observation and targeted genetic testing. Because management is often ongoing rather than a single intervention, this cluster also covers the practical side of long-term care, including what families can generally expect from a developmental or neurology follow-up schedule.
Understanding inheritance
The inheritance basics cluster is the foundation beneath both condition clusters. It walks through how dominant, recessive, X-linked, and de novo patterns actually work, and introduces related concepts such as genomic imprinting, where the parent of origin of a gene copy affects whether it is active. Readers often find it useful to start here before reading about a specific condition, since the inheritance pattern explains much of what a genetic counselor will discuss with a family.
Genetic testing and counseling
Our genetic testing and counseling section explains, in general terms, what genetic testing can and cannot tell a family, and what a genetic counseling appointment typically involves. It is meant to help someone walk into that appointment with better questions, not to replace it.
Explore the full set of conditions
For a complete list of every condition and topic covered on this site, visit our conditions index. It links to each pillar and every supporting article in both clusters, along with our glossary of genetic terms used throughout the site.
How to use this site
Clinical Genetics Primer is an educational resource, not a diagnostic tool. Reading about a condition here cannot confirm or rule it out, and no page on this site is a substitute for an evaluation by a qualified clinician or a genetic counselor. If you or a family member have symptoms or a family history that concerns you, the right next step is a conversation with a healthcare provider, who can arrange appropriate testing and interpret the results in context.
What this means in practice is that we aim to give you the vocabulary and the framework to follow that conversation closely, ask informed questions, and understand what your clinician tells you. We will keep expanding this reference as we add new condition pages and supporting material.