Disease & care
Medical Glossary
A practical glossary for terms used on this site: meaning, where you might see them, when you might encounter them, with examples and links — not a diagnostic checklist.
Last reviewed: September 2026
How to read this page
Each term uses three columns:
- Column 1: name, abbreviation if any, related-page link, and context badges (lab, genetics, and so on) only when they truly apply.
- Column 2: What is it? Where might you see it? When might you encounter it? — practical wording for families and clinics.
- Column 3: Where on this site? and a practical example that illustrates use without making the term mandatory for every patient.
This page is not a diagnostic checklist. Full scientific context and limits live on the disease, treatment, what-we-know, and sources pages.
“Where might you see it” does not mean “the clinician must order it.” Examples are illustrative only.
Carbonic Anhydrase IICA II / CA2
Related page
Genetics Bone Kidney Research
What is it?
An enzyme that helps some tissues regulate acid–base balance. It is encoded by the CA2 gene.
Where might you see it?
In genetics reports, disease summaries, and papers discussing “CA II deficiency” or CA2-related disease.
When might you encounter it?
When explaining the diagnosis or comparing bone, kidney, and neurologic features linked to this condition.
Where on this site?
About the disease · Treatment · What we know
Practical example
A genetics report listing CA2 variants together with osteopetrosis and renal tubular acidosis may lead clinicians to describe carbonic anhydrase II deficiency — severity still varies between people.
Renal Tubular AcidosisRTA
Related page
Kidney Lab Clinic Clinical reports
What is it?
A problem with how the kidneys manage blood acidity; it is not automatically the same as global kidney failure.
Where might you see it?
In nephrology diagnoses, follow-up summaries, and acid–base or electrolyte results.
When might you encounter it?
When discussing acidosis, bicarbonate, potassium, or individualized alkali support decided by the care team.
What is it?
An RTA pattern mainly linked to impaired acidification in the distal nephron.
Where might you see it?
In nephrology reports or differential classification of RTA.
When might you encounter it?
When a clinician or report describes distal features within tubular acidosis.
Where on this site?
Treatment — RTA · RTA in the glossary
Practical example
“Distal RTA” names a physiologic pattern. In CA II deficiency, distal features may appear within a mixed picture and are not a fixed label for every case.
What is it?
An RTA pattern linked to impaired bicarbonate reabsorption in the proximal tubule.
Where might you see it?
In kidney reports or discussions of urinary bicarbonate loss.
When might you encounter it?
When interpreting low HCO3 or alkali needs within RTA follow-up.
Where on this site?
Treatment — RTA · Bicarbonate
Practical example
Mention of “proximal bicarbonate wasting” can signal proximal features; it is a clinical/lab description, not a ready-made prescription.
What is it?
Wording used when reports describe proximal and distal features together; common in published CA II deficiency cases.
Where might you see it?
In diagnostic summaries or case reports describing mixed tubular acidosis.
When might you encounter it?
When comparing patient reports or reading the treatment page on RTA in CA II.
Where on this site?
Treatment — RTA · What we know
Practical example
Many CA II reports use “mixed RTA”; that does not mean every patient shares the same label or the same follow-up plan.
What is it?
A measure of how acidic or alkaline blood or body fluids are.
Where might you see it?
On blood gas results and some electrolyte/acid–base panels.
When might you encounter it?
During illness, acidosis follow-up, or clinic review of laboratory results.
What is it?
A key buffer that helps offset acidity; often reported on blood gas or chemistry panels as HCO3 or bicarbonate.
Where might you see it?
On arterial/venous blood gas reports and clinical chemistry panels.
When might you encounter it?
During renal tubular acidosis follow-up, or when the team adjusts individualized alkali support — not as a mandatory test in every situation.
What is it?
An electrolyte important for muscle and heart function; often monitored in RTA care plans.
Where might you see it?
On serum electrolyte panels and sometimes in home logs requested by clinic teams.
When might you encounter it?
When reviewing labs, muscle/heart symptoms the team links to electrolytes, or adjusting supportive therapy.
Where on this site?
Treatment — RTA · Family toolkit
Practical example
Low potassium may enter an RTA discussion; this site does not interpret a single number or suggest unsupervised replacement.
What is it?
An inheritance pattern that usually requires two pathogenic gene copies for disease expression.
Where might you see it?
In genetic counseling letters, sequencing reports, and disease explainers.
When might you encounter it?
When discussing recurrence risk or reading “AR inheritance” in a report.
What is it?
Pathogenic changes affecting both alleles of the gene.
Where might you see it?
In molecular genetics reports and genetic diagnosis summaries.
When might you encounter it?
When reading results such as “biallelic pathogenic variants in CA2”.
Where on this site?
About the disease · Variant pathway
Practical example
Biallelic CA2 variants support a genetic diagnosis of CA II deficiency when clinical features fit — final interpretation rests with the reporting laboratory and clinical genetics.
What is it?
A DNA sequence change; not every change causes disease, and pathogenicity needs expert interpretation.
Where might you see it?
In NGS/CA2 sequencing reports, databases, and research discussions.
When might you encounter it?
When receiving a genetics result or reading papers about CA2 variants.
Where on this site?
Variant pathway · Variant-effect types · Library
Practical example
A “VUS” (variant of uncertain significance) is not the same as a pathogenic call; this site does not reclassify individual variants outside the laboratory report.
What is it?
A variant affecting RNA splicing signals, which can change production of functional protein.
Where might you see it?
In genetics reports naming splice positions such as c.232+1G>A or related changes.
When might you encounter it?
When discussing variants reported in published cohorts — without assuming identical severity for every person.
What is it?
An insertion or deletion that shifts the reading frame and may cause major loss of function, depending on molecular context.
Where might you see it?
In molecular-effect descriptions within reports or papers.
When might you encounter it?
When classifying molecular lesion type in genotype–phenotype discussions.
What is it?
A variant that reduces enzyme function without necessarily abolishing it (reduced residual activity).
Where might you see it?
In molecular papers and discussions linking variant class to severity.
When might you encounter it?
When comparing severe loss-of-function alleles with residual-function examples from the literature.
Where on this site?
H107Y spotlight · Residual activity
Practical example
Roth et al. (PMID 1542674) described H107Y with detectable but greatly reduced activity — a research example, not a routine clinic assay for every patient.
What is it?
How much CA II enzyme activity remains after a genetic change; important in the literature and not routinely available in every clinic.
Where might you see it?
More often in molecular/lab studies than in day-to-day clinic printouts.
When might you encounter it?
When interpreting why some published variants associate with milder features — without over-generalizing to one person.
Where on this site?
Variant pathway · H107Y · Research gaps
Practical example
Published residual activity for one variant does not mean every clinic can measure the same activity for every patient today.
What is it?
The person’s genetic variant configuration (what is present in the gene).
Where might you see it?
In sequencing reports, family studies, and paper tables.
When might you encounter it?
When comparing people with different variants or reading genotype–phenotype sections.
Where on this site?
Clinical heterogeneity · Variant pathway
Practical example
The same clinical label “CA II deficiency” can map to different genotypes; genotype is part of the picture, not the whole care decision.
What is it?
Observable clinical and laboratory features (what is seen in the patient).
Where might you see it?
In clinical summaries, case tables, and bone/kidney/neurologic follow-up.
When might you encounter it?
When describing severity, complications, or differences among relatives.
Where on this site?
About the disease · Treatment · What we know
Practical example
A severe skeletal phenotype may coexist with variable renal acidosis; this site emphasizes heterogeneity rather than one mandatory picture.
Genotype–phenotype correlation
Related page
Genetics Research Treatment
What is it?
Efforts to relate variant type to clinical severity or residual activity — observed associations, not deterministic rules for individuals, and not mutation-specific drug selection.
Where might you see it?
In genetics research, literature reviews, and treatment sections on heterogeneity.
When might you encounter it?
When comparing variant class with disease severity, or reading the H107Y example and related published variants.
Where on this site?
Heterogeneity · H107Y · What we know · Research gaps
Practical example
Example: H107Y in PMID 1542674 had residual activity and relatively milder features in a compound-heterozygous context — supporting correlation without proving mutation-guided prescribing.
What is it?
Increased bone density that can still involve fragility or cranial complications despite a denser radiographic appearance.
Where might you see it?
In radiology reports, bone summaries, and genetic osteopetrosis literature.
When might you encounter it?
When discussing fractures, cranial nerve compromise, or selected severe cases where HSCT is considered.
Where on this site?
About the disease · HSCT · Treatment
Practical example
Osteopetrosis in CA II deficiency does not automatically mean therapies used in other osteopetrosis types are appropriate; the treatment page warns against that generalization.
Cerebral calcification
Related page
Neurology Imaging Clinical reports
What is it?
Calcium deposits in the brain reported on some imaging studies; described in many published CA II cases, not universal at every age.
Where might you see it?
In CT/MRI reports or neurology summaries.
When might you encounter it?
When following neurologic features or comparing calcification trajectory across published follow-up.
Where on this site?
About the disease · What we know · Research gaps
Practical example
Later calcification after transplant in some published HSCT contexts shows neurologic pathways may continue — without generalizing to every patient.
Hematopoietic Stem Cell TransplantationHSCT
Related page
Transplant Bone Treatment Research
What is it?
Transplant of blood-forming stem cells; discussed by specialists in selected situations, not standard care for every person with CA II deficiency.
Where might you see it?
In the scientific literature, case reports, and transplant-center discussions for selected severe skeletal disease.
When might you encounter it?
When weighing possible skeletal benefit against persistence of RTA or neurologic features; decisions are individualized and multidisciplinary.
What is it?
Care that supports physiology and complications (such as acid–base and electrolyte management) without claiming to cure the genetic cause.
Where might you see it?
In clinic plans, treatment pages, and family organizing tools for follow-up.
When might you encounter it?
In most day-to-day care pathways for CA II deficiency, where individualized support is the published mainstay.
What is it?
The follow-up and interventions set by the treating team for an individual — not a mandatory universal algorithm for this rare disease.
Where might you see it?
In multidisciplinary clinic summaries and this site’s treatment page.
When might you encounter it?
When coordinating kidney, bone, genetics, and neurology visits, or discussing limited-evidence options.