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Disease Profile

Marie Unna congenital hypotrichosis

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset






Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

MUHH; Hypotrichosis, Marie Unna type; Marie Unna hereditary hypotrichosis


Congenital and Genetic Diseases; Skin Diseases


The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs.

Orpha Number: 444

A rare autosomal dominant hair loss disorder characterized by the absence or scarcity of scalp hair, eyebrows, and eyelashes at birth; coarse and wiry hair during childhood; and progressive hair loss beginning around puberty.

Prevalence and incidence are unknown.

Clinical description
Affected individuals of both sexes are typically born with an absence or scarcity of scalp hair, eyelashes, and eyebrows. During early childhood the scalp hair becomes coarse and wiry. Loss of scalp hair begins around puberty in a pattern resembling that of androgenetic alopecia and progresses to almost total alopecia. Body, axillary, and pubic hair is sparse or absent as is beard hair in men and adolescent boys. No other ectodermal abnormalities are observed.

MUHH is due to mutations in U2HR, an inhibitory upstream open reading frame of the HR gene located to 8p21.2, causing a gain of function of HR. Worldwide, more than 15 different U2HR mutations have been identified in nearly 30 affected families and sporadic cases. Recently, a missense mutation in EPS8L3, located on chromosome 1p13.2, was identified in a Chinese family with MUHH.

Diagnostic methods
Diagnosis depends on clinical and microscopic examination and can be confirmed by mutational analysis of U2HR. Scanning electron microscopic study of the hair reveals irregular twisting, longitudinal ridging and cuticle peeling. Scalp biopsy shows a marked reduction in the number of follicles with follicular fibrosis. However, the small number of biopsies analyzed makes it difficult to obtain an objective impression.

Differential diagnosis
Differential diagnoses include hypotrichosis simplex, loose anagen syndrome, uncombable hair syndrome, ectodermal dysplasia syndromes (see these terms), congenital atrichia, androgenetic alopecia and alopecia areata.

Antenatal diagnosis
Antenatal diagnosis can be performed but is the exception, as MUHH is not a life-threatening disease. Therefore in practice, this is handled in quite a restrictive manner.

Genetic counseling
There is a 50% recurrence risk for offspring of affected individuals as transmission is autosomal dominant.

Management and treatment
No curative treatment exists for MUHH.

Life expectancy is normal but quality of life can be reduced due to the psychological impact related to the hair phenotype.

Visit the Orphanet disease page for more resources.


This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
80%-99% of people have these symptoms
Hair loss
Aplasia/Hypoplasia of the eyebrow
Absence of eyebrow
Lack of eyebrow
Missing eyebrow

[ more ]

Coarse hair
Coarse hair texture
Sparse or absent eyelashes
Sparse scalp hair
Reduced/lack of hair on scalp
Scalp hair, thinning
Sparse, thin scalp hair
sparse-absent scalp hair

[ more ]

Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance
Pili torti
Flattened and twisted hair
Sparse and thin eyebrow
Thin, sparse eyebrows
Sparse body hair
Sparse eyelashes
Scant eyelashes
Scanty eyelashes
Thin eyelashes

[ more ]

Sparse hair


Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.


    Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

    Organizations Supporting this Disease

      Learn more

      These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

      In-Depth Information

      • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
      • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
      • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
      • PubMed is a searchable database of medical literature and lists journal articles that discuss Marie Unna congenital hypotrichosis. Click on the link to view a sample search on this topic.