A dysmorphic feature is an abnormal difference in body structure. It can be an isolated finding in an otherwise normal individual, or it can be related to a

congenital disorder A birth defect is an abnormal condition that is present at childbirth, birth, regardless of its cause. Birth defects may result in disability, disabilities that may be physical disability, physical, intellectual disability, intellectual, or dev ...

, genetic

syndrome A syndrome is a set of medical signs and symptoms which are correlated with each other and often associated with a particular disease or disorder. The word derives from the Greek language, Greek σύνδρομον, meaning "concurrence". When a sy ...

birth defect A birth defect is an abnormal condition that is present at birth, regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can range from mild to severe. Birth de ...

. Dysmorphology is the study of dysmorphic features, their origins and proper nomenclature. One of the key challenges in identifying and describing dysmorphic features is the use and understanding of specific terms between different individuals. Clinical geneticists and

pediatrician Pediatrics (American English) also spelled paediatrics (British English), is the branch of medicine that involves the medical care of infants, children, adolescents, and young adults. In the United Kingdom, pediatrics covers many of their youth ...

s are usually those most closely involved with the identification and description of dysmorphic features, as most are apparent during childhood. Dysmorphic features can vary from isolated, mild anomalies such as clinodactyly or synophrys to severe congenital anomalies, such as heart defects and

holoprosencephaly Holoprosencephaly (HPE) is a cephalic disorder in which the prosencephalon (the forebrain of the embryo) fails to Prenatal development, develop into two Cerebral hemisphere, hemispheres, typically occurring between the 18th and 28th day of gestati ...

. In some cases, dysmorphic features are part of a larger clinical picture, sometimes known as a

sequence In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed and order matters. Like a set, it contains members (also called ''elements'', or ''terms''). The number of elements (possibly infinite) is cal ...

or association. Recognizing the patterns of dysmorphic features is an important part of a geneticist's diagnostic process, as many genetic disease present with a common collection of features. There are several commercially available databases that allow clinicians to input their observed features in a patient to generate a differential diagnosis. These databases are not infallible, as they require on the clinician to provide their own experience, particularly when the observed clinical features are general. A male child with

short stature Short stature refers to a height of a human which is below typical. Whether a person is considered short depends on the context. Because of the lack of preciseness, there is often disagreement about the degree of shortness that should be called ...

and

hypertelorism Hypertelorism is an abnormally increased distance between two organs or bodily parts, usually referring to an increased distance between the orbits (eyes), or orbital hypertelorism. In this condition, the distance between the inner eye corners, a ...

could have several different disorders, as these findings are not highly specific. However a finding such as 2,3-toe

syndactyly Syndactyly is a condition wherein two or more digits are fused together. It occurs normally in some mammals, but is an unusual condition in humans. The term is . Classification Syndactyly can be simple or complex. * In simple syndactyly, adja ...

raises the index of suspicion for

Smith–Lemli–Opitz syndrome Smith–Lemli–Opitz syndrome is an inborn error of metabolism, inborn error of cholesterol synthesis. It is an autosome, autosomal recessive (genetics), recessive, multiple malformation syndrome caused by a mutation in the enzyme 7-Dehydrochole ...

. Most open source projects that perform phenotype-driven disease or gene prioritization work with the terminology of the Human Phenotype Ontology. This controlled vocabulary can be used to describe the clinical features of a patient and is suitable for machine learning approaches. Publicly accessible databases that labs use to deposit their diagnostic findings, such as

ClinVar ClinVar is a public archive with free access to reports on the relationships between human variations and phenotypes, with supporting evidence. The database includes germline and somatic variants of any size, type or genomic location. Interpretation ...

, can be used to build

knowledge graph In knowledge representation and reasoning, a knowledge graph is a knowledge base that uses a Graph (discrete mathematics), graph-structured data model or topology to represent and operate on data. Knowledge graphs are often used to store interl ...

s to explore the clinical feature space. Dysmorphic features are invariably present from birth, although some are not immediately apparent upon

visual inspection Visual inspection is a common method of quality control, data acquisition, and data analysis. Visual Inspection, used in maintenance of facilities, mean inspection of equipment and structures using either or all of raw human senses such as vision, ...

. They can be divided into groups based on their origin, including

malformation A birth defect is an abnormal condition that is present at birth, regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can range from mild to severe. Birth de ...

s (abnormal development), disruptions (damage to previously normal tissue), deformations (damage caused by an outside physical force) and

dysplasia Dysplasia is any of various types of abnormal growth or development of cells (microscopic scale) or organs (macroscopic scale), and the abnormal histology or anatomical structure(s) resulting from such growth. Dysplasias on a mainly microscopic ...

s (abnormal growth or organization within a tissue).

Dysmorphology

Dysmorphology is the discipline of using dysmorphic features in the diagnostic workup and delineation of syndromic disorders. In the recent years advances in computer vision have also resulted in several

deep learning Deep learning is a subset of machine learning that focuses on utilizing multilayered neural networks to perform tasks such as classification, regression, and representation learning. The field takes inspiration from biological neuroscience a ...

approaches that assist geneticists in the study of the facial gestalt. Training and test data for clinicians and computer scientists in order to compare the performance of new AIs can be obtained from GestaltMatcher.

References

{{reflist Body shape Medical genetics