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PubMed This is a summary of 13 peer-reviewed journal articles Updated
Pediatrics

Grades, Syndromes, and the Biology of Microtia

At a Glance

Microtia is classified into four grades ranging from a slightly smaller ear to the complete absence of the ear (anotia). Because the ears, kidneys, and heart develop simultaneously in the womb, doctors routinely recommend ultrasounds and cardiac evaluations to check for associated conditions.

While microtia is most visible as a difference in the shape of the ear, understanding its biology helps explain why doctors often look closely at other parts of the body. Because the ear develops at the same time as several vital organs, microtia can sometimes be a “clue” to other developmental patterns.

The Biology: The Branchial Arches

The external ear begins to form around the sixth week of pregnancy from six small buds of tissue called the hillocks of His [1][2]. These buds grow from two larger structures known as the first and second branchial arches (also called pharyngeal arches) [2].

These arches are the “building blocks” for much of the face and neck. The first arch helps form the jaw and part of the ear, while the second arch forms other parts of the ear and neck [1]. Microtia occurs when something—often a combination of genetic signals and environmental factors—disrupts the way these arches grow and fuse together [3][4].

Classification: The Four Grades of Microtia

Doctors typically use the Marx classification system to describe the physical appearance of the ear [1]. Knowing your child’s grade helps the care team plan for future hearing support and reconstruction.

Grade Description Appearance
Grade 1 Mild A slightly smaller ear that has all the normal parts (lobule, helix, and concha) [1][5].
Grade 2 Moderate A partial ear that is usually vertical and sausage-shaped; some landmarks are missing [1].
Grade 3 Classic The most common form. A small, peanut-shaped remnant of skin and cartilage with no ear canal [1][5].
Grade 4 Anotia The complete absence of the external ear and ear canal [1].

Isolated vs. Syndromic Microtia

In about 60% to 80% of cases, microtia is isolated, meaning it is the only physical difference the child has [6]. However, in other cases, it is syndromic, meaning it occurs alongside other developmental differences. Common syndromes associated with microtia include:

  • Goldenhar Syndrome (OAVS): This may involve underdevelopment of one side of the face (hemifacial microsomia), cysts on the eye, or differences in the bones of the spine [7][8].
  • Treacher Collins Syndrome: This usually affects both sides of the face and involves differences in the cheekbones, jaw, and eyelids [9].

Why Screening Matters

Because the ears, kidneys, and heart develop during the same window of time in the womb, a disruption in one can sometimes affect the others [10][11]. Even when microtia appears to be isolated, your doctor may recommend the following screenings to ensure everything else is functioning correctly:

  • Renal Ultrasound: A painless scan to check that the kidneys are properly formed and located, as renal anomalies are more common in children with microtia [6][11].
  • Cardiac Evaluation: A thorough physical exam, and sometimes an echocardiogram (heart ultrasound), to check for heart murmurs or structural differences [6][12].
  • Spine X-rays: Specifically for the neck (cervical spine) if a syndrome like Goldenhar is suspected, to ensure the vertebrae are properly aligned [8].

Early screening is not a cause for alarm; rather, it is a proactive step to ensure your child receives comprehensive care from the very beginning [13].

For more information on the next steps regarding hearing, visit Hearing Loss and Early Intervention.

Common questions in this guide

What are the four grades of microtia?
Microtia is classified into four grades based on the ear's appearance. Grade 1 is a mildly smaller ear, Grade 2 is a partial sausage-shaped ear, Grade 3 is a peanut-shaped ear with no canal, and Grade 4 is the complete absence of the ear.
What is the difference between isolated and syndromic microtia?
Isolated microtia means the ear difference is the only physical variation your child has, which accounts for the majority of cases. Syndromic microtia occurs alongside other developmental conditions, such as Goldenhar Syndrome or Treacher Collins Syndrome.
Why does my baby need a kidney ultrasound for an ear condition?
A baby's ears and kidneys develop during the same timeframe during pregnancy. Because of this shared developmental window, doctors recommend a painless renal ultrasound to ensure the kidneys are properly formed, even if the microtia appears isolated.
Will my child need heart or spine tests because of microtia?
Your doctor may recommend an echocardiogram or spine X-rays to check for structural differences. Like the kidneys, the heart and spine develop at the same time as the ears, so proactive screening ensures your child receives comprehensive care.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Based on my child's ear shape, what grade of microtia do they have according to the Marx classification?
  2. 2.Is my child's microtia considered 'isolated' or 'syndromic' based on your initial examination?
  3. 3.Should we schedule a renal ultrasound to check my child's kidneys, even if the microtia appears isolated?
  4. 4.Do you recommend a consultation with a geneticist to screen for conditions like Goldenhar or Treacher Collins syndrome?
  5. 5.Are there any signs of vertebral (spine) or cardiac (heart) differences that we should investigate further?

Questions For You

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References

References (13)
  1. 1

    Genetic Advances in the Understanding of Microtia.

    Gendron C, Schwentker A, van Aalst JA

    Journal of pediatric genetics 2016; (5(4)):189-197 doi:10.1055/s-0036-1592422.

    PMID: 27895971
  2. 2

    Functional Pathway and Process Enrichment Analysis of Genes Associated With Morphological Abnormalities of the Outer Ear.

    Meng X, Pan B, Zhang Z, et al.

    The Journal of craniofacial surgery 2023; (34(2)):489-493 doi:10.1097/SCS.0000000000008904.

    PMID: 35973123
  3. 3

    Identification of a novel phenotype of external ear deformity related to Coffin-Siris syndrome-9 and literature review.

    Wu R, Tang W, Li P, et al.

    American journal of medical genetics. Part A 2024; (194(8)):e63626 doi:10.1002/ajmg.a.63626.

    PMID: 38591849
  4. 4

    Identification of a second HOXA2 nonsense mutation in a family with autosomal dominant non-syndromic microtia and distinctive ear morphology.

    Piceci F, Morlino S, Castori M, et al.

    Clinical genetics 2017; (91(5)):774-779 doi:10.1111/cge.12845.

    PMID: 27503514
  5. 5

    International Consensus Recommendations on Microtia, Aural Atresia and Functional Ear Reconstruction.

    Zhang TY, Bulstrode N, Chang KW, et al.

    The journal of international advanced otology 2019; (15(2)):204-208 doi:10.5152/iao.2019.7383.

    PMID: 31418720
  6. 6

    Renal anomalies and microtia: Determining the clinical utility of screening affected children.

    Kini S, Barton GW, Carol Liu YC

    International journal of pediatric otorhinolaryngology 2020; (133()):109957 doi:10.1016/j.ijporl.2020.109957.

    PMID: 32109674
  7. 7

    Congenital abnormalities associated with microtia: A 10-YEARS retrospective study.

    Paul A, Achard S, Simon F, et al.

    International journal of pediatric otorhinolaryngology 2021; (146()):110764 doi:10.1016/j.ijporl.2021.110764.

    PMID: 33992972
  8. 8

    Vertebral Anomalies in Microtia Patients at a Tertiary Pediatric Care Center.

    Alexander NL, McLennan A, Silva RC, et al.

    Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery 2023; (169(2)):367-373 doi:10.1002/ohn.289.

    PMID: 36805618
  9. 9

    Retinoic Acid Embryopathy.

    Mondal D, R Shenoy S, Mishra S

    International journal of applied & basic medical research 2017; (7(4)):264-265 doi:10.4103/ijabmr.IJABMR_469_16.

    PMID: 29308367
  10. 10

    Goldenhar Syndrome: An Atypical Presentation With Developmental and Speech Delay.

    Jayaprakasan SK, Waheed MD, Batool S, et al.

    Cureus 2023; (15(3)):e36225 doi:10.7759/cureus.36225.

    PMID: 37069882
  11. 11

    Utilization of Diagnostic Testing for Renal Anomalies and Congenital Heart Disease in Patients with Microtia.

    Ramprasad VH, Shaffer AD, Jabbour N

    Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery 2020; (162(4)):554-558 doi:10.1177/0194599820901351.

    PMID: 31959051
  12. 12

    Epidemiological Research of Microtia Combined With Congenital Heart Disease.

    Cao T, Chen Q, Wang B, et al.

    The Journal of craniofacial surgery 2021; (32(3)):920-924 doi:10.1097/SCS.0000000000007296.

    PMID: 33252535
  13. 13

    Cardiac anomalies in microtia patients at a tertiary pediatric care center.

    Alexander NL, Kini SD, Liu YC

    International journal of pediatric otorhinolaryngology 2020; (136()):110211 doi:10.1016/j.ijporl.2020.110211.

    PMID: 32797804

This page provides educational information about microtia grades, syndromes, and biology. Always consult your child's pediatrician or pediatric ENT for an official diagnosis and personalized screening plan.

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