Proband
Encyclopedia
Proband, or propositus, is a term used most often in medical genetics
and other medical fields to denote a particular subject (person or animal) being studied or reported on. On pedigrees
, the proband is noted with an arrow and the box (male) or circle (female) shaded accordingly. It is important to denote the proband, so that the relationship to other individuals can be seen and patterns established.
In many cases, the proband is the first affected family member who seeks medical attention for a genetic disorder
. Between the ancestor
s of the proband, there are very likely other subjects with the manifest disease, but they might be unknown due to the lack of information regarding those individuals or the disease at the time they lived. Other ancestors might be undiagnosed due to the incomplete penetrance
or variable expressivity
.
The diagnosis of a proband raises the index of suspicion for the proband's relatives and some of them may be diagnosed with the same disease. Conventionally, when drawing a pedigree chart
, instead of the first diagnosed person, the proband may be chosen from among the affected ancestor
s (parents, grandparents) from the first generation where the disease is found.
The term proband is also used in genealogy
, where it denotes the root node of an Ahnentafel
.
Medical genetics
Medical genetics is the specialty of medicine that involves the diagnosis and management of hereditary disorders. Medical genetics differs from Human genetics in that human genetics is a field of scientific research that may or may not apply to medicine, but medical genetics refers to the...
and other medical fields to denote a particular subject (person or animal) being studied or reported on. On pedigrees
Pedigree chart
A pedigree chart is a diagram that shows the occurrence and appearance or phenotypes of a particular gene or organism and its ancestors from one generation to the next, most commonly humans, show dogs, and race horses....
, the proband is noted with an arrow and the box (male) or circle (female) shaded accordingly. It is important to denote the proband, so that the relationship to other individuals can be seen and patterns established.
In many cases, the proband is the first affected family member who seeks medical attention for a genetic disorder
Genetic disorder
A genetic disorder is an illness caused by abnormalities in genes or chromosomes, especially a condition that is present from before birth. Most genetic disorders are quite rare and affect one person in every several thousands or millions....
. Between the ancestor
Ancestor
An ancestor is a parent or the parent of an ancestor ....
s of the proband, there are very likely other subjects with the manifest disease, but they might be unknown due to the lack of information regarding those individuals or the disease at the time they lived. Other ancestors might be undiagnosed due to the incomplete penetrance
Penetrance
Penetrance in genetics is the proportion of individuals carrying a particular variant of a gene that also express an associated trait . In medical genetics, the penetrance of a disease-causing mutation is the proportion of individuals with the mutation who exhibit clinical symptoms...
or variable expressivity
Expressivity
Expressivity is a term used in genetics to refer to variations in a phenotype among individuals carrying a particular genotype. The term can be used to characterize qualitatively or quantitatively the extent of phenotypic variation given a particular genotype. The term is analogous to the...
.
The diagnosis of a proband raises the index of suspicion for the proband's relatives and some of them may be diagnosed with the same disease. Conventionally, when drawing a pedigree chart
Pedigree chart
A pedigree chart is a diagram that shows the occurrence and appearance or phenotypes of a particular gene or organism and its ancestors from one generation to the next, most commonly humans, show dogs, and race horses....
, instead of the first diagnosed person, the proband may be chosen from among the affected ancestor
Ancestor
An ancestor is a parent or the parent of an ancestor ....
s (parents, grandparents) from the first generation where the disease is found.
The term proband is also used in genealogy
Genealogy
Genealogy is the study of families and the tracing of their lineages and history. Genealogists use oral traditions, historical records, genetic analysis, and other records to obtain information about a family and to demonstrate kinship and pedigrees of its members...
, where it denotes the root node of an Ahnentafel
Ahnentafel
An ahnentafel or ahnenreihe is a genealogical numbering system for listing a person's direct ancestors in a fixed sequence of ascent...
.