Microtia
Page most recently updated 7 September 2026
This page focuses on microtia as a morphologic feature of conditions that may also be associated with psychiatric manifestations, such as psychosis, mania, autism spectrum disorder, ADHD, OCD, and self-injurious behaviours. The page begins with a clinical definition of microtia based on the standardized Elements of Morphology terminology, together with visual examples from the same source. This is followed by a list of conditions in which microtia has been described in association with psychiatric manifestations.
Of note, to optimize clinical utility, the list does not include conditions associated with intellectual disability in the absence of other psychiatric features.
Each condition listed below is linked to a dedicated page within this resource. These pages describe the psychiatric manifestations associated with each condition, as well as other morphologic and broader clinical features, allowing the differential diagnosis to be considered from multiple perspectives.
Anatomy of the ear
Image credit: National Human Genome Research Institute (NHGRI), Elements of Morphology.
Definition
Objective:
First Degree: Presence of all the normal ear components and the median longitudinal length more than 2 SD below the mean.
Second Degree: Median longitudinal length of the ear more than 2 SD below the mean in the presence of some, but not all, parts of the ear.
Third Degree: Presence of some auricular structures, but none of these structures conform to recognized ear components.
Note: Third Degree Microtia is commonly associated with atresia of the external canal, but that anomaly should be considered separately. Complete absence of the ear should be described as Anotia.
Replaces (replaced by Microtia, Second Degree): Ear, Grade II Dysplasia; Ear, Cupped Severe, Type III; Ear, Cockleshell; Ear, Constricted Helix Type IV; Ear, Snail; Ear, Shell; Ear, Mini.
Replaces (replaced by Microtia, Third Degree): Ear, Grade III Dysplasia; Ear, Hypoplastic, Group II; Ear, Peanut.
Conditions with potential psychiatric associations
Selected references and further reading — Morphologic lens
Allanson JE, Biesecker LG, Carey JC, Hennekam RCM. Elements of morphology: introduction. Am J Med Genet A. 2009;149A(1):2-5.
Hennekam RCM, Biesecker LG, Allanson JE, Hall JG, Opitz JM, Temple IK, Carey JC; Elements of Morphology Consortium. Elements of morphology: general terms for congenital anomalies. Am J Med Genet A. 2013;161A(11):2726-2733.
Jones KL, Jones MC, del Campo M. Smith's recognizable patterns of human malformation. 8th ed. Philadelphia: Elsevier; 2021.
Reardon W. The bedside dysmorphologist: a guide to identifying and assessing congenital malformations. 2nd ed. Oxford: Oxford University Press; 2016.