Marie Unna congenital hypotrichosis

Alternate names

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

Definition

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.

Epidemiology

Prevalence and incidence are unknown.

Cause

• 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.

Inheritance

Autosomal dominant pattern, a 50/50 chance.

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

Signs and symptoms

• 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.

Clinical description

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

• Alopecia(Hair loss)
• Aplasia/Hypoplasia of the eyebrow(Absence of eyebrow)
• Coarse hair(Coarse hair texture)
• Sparse or absent eyelashes
• Sparse scalp hair(Reduced/lack of hair on scalp)

Diagnosis

• 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.

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.

Treatment

No curative treatment exists for MUHH.

Prognosis

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

NIH genetic and rare disease info

• NIH info on Marie Unna congenital hypotrichosis

Marie Unna congenital hypotrichosis is a rare disease.

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