A pedigree chart is a diagram that shows the occurrence of certain traits through different generations of a family, most commonly for

humans Humans (''Homo sapiens'') or modern humans are the most common and widespread species of primate, and the last surviving species of the genus ''Homo''. They are Hominidae, great apes characterized by their Prehistory of nakedness and clothing ...

, show dogs, and race

horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 mi ...

Definition

The word pedigree is a corruption of the Anglo-Norman French ''pé de grue'' or "crane's foot", either because the typical lines and split lines (each split leading to different offspring of the one parent line) resemble the thin leg and foot of a crane or because such a mark was used to denote succession in pedigree charts. A pedigree results in the presentation of family information in the form of an easily readable chart. It can be simply called a "

family tree A family tree, also called a genealogy or a pedigree chart, is a chart representing family relationships in a conventional tree structure. More detailed family trees, used in medicine and social work, are known as genograms. Representations of ...

". Pedigrees use a standardized set of symbols, squares represent males and circles represent females. Pedigree construction is a family history, and details about an earlier generation may be uncertain as memories fade. If the sex of the person is unknown, a diamond is used. Someone with the

phenotype In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology (physical form and structure), its developmental processes, its biochemical and physiological propert ...

(trait) in question is represented by a filled-in (darker) symbol. Heterozygotes, when identifiable, are indicated by a shaded dot inside a symbol or a half-filled symbol. Relationships in a pedigree are shown as a series of lines. A horizontal line connects parents and a vertical line leads to their offspring. The offspring are connected by a horizontal sibship line and listed in birth order from left to right. If the offspring are twins then they will be connected by a triangle. If an offspring dies then its symbol will be crossed by a line. If the offspring is stillborn or aborted, it is represented by a small triangle. Each generation is identified by a

Roman numeral Roman numerals are a numeral system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Numbers are written with combinations of letters from the Latin alphabet, ea ...

(I, II, III, and so on), and each individual within the same generation is identified by an

Arabic numeral The ten Arabic numerals (0, 1, 2, 3, 4, 5, 6, 7, 8, and 9) are the most commonly used symbols for writing numbers. The term often also implies a positional notation number with a decimal base, in particular when contrasted with Roman numerals. ...

(1, 2, 3, and so on). Analysis of the pedigree using the principles of

Mendelian inheritance Mendelian inheritance (also known as Mendelism) is a type of biological inheritance following the principles originally proposed by Gregor Mendel in 1865 and 1866, re-discovered in 1900 by Hugo de Vries and Carl Correns, and later popularize ...

can determine whether a trait has a dominant or recessive pattern of inheritance. Pedigrees are often constructed after a family member afflicted with a genetic disorder has been identified. This individual, known as the

proband In medical genetics and other medical fields, a proband, propositus (male proband), or proposita (female proband) is a particular subject (human or other animal) being studied or reported on. On pedigrees, the proband is noted with a square (male) ...

, is indicated on the pedigree by an arrow. These changes may occur yearly or monthly. File:Wiki Drawing - Y-Linked (1).svg, In a Y-linked disorder, only males can be affected. If the father is affected all sons will be affected. It also does not skip a generation. File:Wiki Drawing - Mitochondrial.svg, Mitochondrial disorders are only passed on if the mother is affected. If the mother is affected, all offspring will be affected. If the father is affected, he does not pass the disorder on to his offspring. File:Wiki Drawing - Autosomal Recessive (2).svg, In an autosomal recessive disorder, it is possible for both parents to not express the trait but, if both are carriers, for their offspring to express the trait. Autosomal recessive disorders typically skip a generation, so affected offspring typically have unaffected parents. With an autosomal recessive disorder, both males and females are equally likely to be affected. File:Wiki Drawing - Autosomal Dominant (1).svg, Autosomal dominant disorders do not skip a generation, so affected offspring have affected parents. One parent must have the disorder for their offspring to be affected. Both males and females are equally likely to be affected, so it is an autosomal disorder. File:Wiki Drawing - X-Linked Recessive (1).svg, In an X-linked recessive disorder, males are more likely to be affected than females. Affected sons typically have unaffected mothers. The father also must be affected for the daughter to be affected, and the mother must be affected or a carrier for the daughter to be affected. The disorder is also never passed from father to son. Only females can be carriers for the disorders. X-linked recessive disorders also typically skip a generation. File:Wiki Drawing - X-Linked Dominant (1).svg, In an X-linked dominant disorder, if the father is affected, all daughters will be affected and no sons will be affected. It does not skip a generation, and the mother has a 50% chance of passing it on to her offspring if she is affected.

In human use

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

and

Wales Wales ( ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by the Irish Sea to the north and west, England to the England–Wales border, east, the Bristol Channel to the south, and the Celtic ...

pedigrees are officially recorded in the

College of Arms The College of Arms, or Heralds' College, is a royal corporation consisting of professional Officer of Arms, officers of arms, with jurisdiction over England, Wales, Northern Ireland and some Commonwealth realms. The heralds are appointed by the ...

, which has records going back to the Middle Ages, including pedigrees collected during roving inquiries by its

herald A herald, or a herald of arms, is an officer of arms, ranking between pursuivant and king of arms. The title is commonly applied more broadly to all officers of arms. Heralds were originally messengers sent by monarchs or noblemen ...

s during the sixteenth and seventeenth centuries. The purpose of these

heraldic visitation Heraldic visitations were tours of inspection undertaken by Kings of Arms (or alternatively by heralds, or junior officers of arms, acting as the kings' deputies) throughout England, Wales and Ireland. Their purpose was to register and regulat ...

s was to register and regulate the use of

coats of arms A coat of arms is a heraldic visual design on an escutcheon (i.e., shield), surcoat, or tabard (the last two being outer garments), originating in Europe. The coat of arms on an escutcheon forms the central element of the full heraldic ac ...

. Those who claimed the right to bear arms had to provide proof either of a grant of arms to them by the College, or of descent from an ancestor entitled to arms. It was for this reason that pedigrees were recorded by the visitations. Pedigrees continue to be registered at the College of Arms and kept up to date on a voluntary basis but are not accessible to the general public without payment of a fee. More visible, therefore, are the pedigrees recorded in published works, such as

Burke's Peerage Burke's Peerage Limited is a British genealogical publisher, considered an authority on the order of precedence of noble families and information on the lesser nobility of the United Kingdom. It was founded in 1826, when the Anglo-Irish genea ...

and Burke's

Landed Gentry The landed gentry, or the gentry (sometimes collectively known as the squirearchy), is a largely historical Irish and British social class of landowners who could live entirely from rental income, or at least had a country estate. It is t ...

in the United Kingdom and, in continental

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

by the Almanach de Gotha. A pedigree may be used to establish the probability of a child having a particular disorder or condition. It may be used to discover where the genes in question are located (x, y, or autosome chromosome), and to determine whether a trait is dominant or recessive. When a pedigree shows a condition appearing in a 50:50 ratio between men and women, it is considered

autosomal An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosomal (sex chromosome) pairs, which may have different structures. The DNA in autosome ...

. When the condition predominantly affects males in the pedigree, it is considered x-linked. Some examples of dominant traits include male baldness, astigmatism, and

dwarfism Dwarfism is a condition of people and animals marked by unusually small size or short stature. In humans, it is sometimes defined as an adult height of less than , regardless of sex; the average adult height among people with dwarfism is . '' ...

. Some examples of recessive traits include small eyes, little body hair, and tall stature.

In animal husbandry

In the practice of

selective breeding Selective breeding (also called artificial selection) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant m ...

of animals, particularly in animal fancy and

livestock Livestock are the Domestication, domesticated animals that are raised in an Agriculture, agricultural setting to provide labour and produce diversified products for consumption such as meat, Egg as food, eggs, milk, fur, leather, and wool. The t ...

, including

s, pedigree charts are used to track the ancestry of animals and assist in the planning of suitable breeding programs to enhance desirable traits.

Breed registries A breed registry, also known as a herdbook, studbook or register, in animal husbandry, the hobby of animal fancy, is an official list of animals within a specific breed whose parents are known. Animals are usually registered by their breeders w ...

are formed and are dedicated to the accurate tracking of pedigrees and maintaining accurate records of birth, death, and identifying characteristics of each registered animal.

References

{{Family Classical genetics Diagrams Family trees

Definition

In human use

In animal husbandry

See also

References