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, also known as a congenital disorder, 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 c ...

, 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 σύνδρομον, meaning "concurrence". When a syndrome is paired ...

birth defect A birth defect, also known as a congenital disorder, 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 c ...

. 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 ( also spelled ''paediatrics'' or ''pædiatrics'') is the branch of medicine that involves the medical care of infants, children, adolescents, and young adults. In the United Kingdom, paediatrics covers many of their youth until th ...

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 Clinodactyly is a medical term describing the curvature of a digit (a finger or toe) in the plane of the palm, most commonly the fifth finger (the " little finger") towards the adjacent fourth finger (the " ring finger"). It is a fairly common is ...

synophrys A unibrow (or jacco brow or monobrow; called synophrys in medicine) is a single eyebrow created when the two eyebrows meet in the middle above the bridge of the nose. The hair above the bridge of the nose is of the same color and thickness as t ...

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 develop into two hemispheres, typically occurring between the 18th and 28th day of gestation. Normally, the forebrain is formed a ...

. 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 called ...

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 could have several different disorders, as these findings are not highly specific. However a finding such as 2,3-toe syndactyly raises the index of suspicion for Smith-Lemli-Opitz Syndrome. 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, can be used to build knowledge graphs 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 malformations (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 microscopi ...

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 approaches that assist geneticists in the study of the facial gestalt.

References

{{reflist Body shape Medical genetics