Marie-unna hereditary hypotrichosis.

Marie-Unna type of hereditary hypotrichosis is a rare autosomal dominant disorder that has a distinctive type of hair loss pattern that varies with child's age. It is characterized by sparse or absent hair at birth with regrowth of coarse, wiry twisted hair from childhood, followed by progressive loss on approaching puberty. We report a 12-year-old male child with characteristic clinical features suggestive of hereditary hypotrichosis of Marie-Unna type.

INTRODUCTION

Marie-Unna hereditary hypotrichosis (MUHH) is an autosomal dominant disorder characterized by a distinctive pattern of hair loss. It was first described by Marie-Unna in a German family, where individuals over seven generations were affected by a previously unreported type of congenital hypotrichosis.[1] It, usually, occurs as an isolated hair abnormality. The hair is sparse at birth with a coarse texture, which eventually regrows in childhood with potential hair loss at puberty. We describe a case of MUHH in previously unaffected family.

CASE REPORT

A-12-year-old male child born in an Indian family, who were Dravidian by origin, presented with progressive thinning of hair from past 2 years. He was born at term out of consanguineous marriage. He had sparse hairs on scalp, eyebrows and eyelashes at birth. Eventually, there was regrowth of coarse, curly hairs, and later the child had progressive hair fall from past 2 years. Natal and perinatal history was normal. His developmental milestones were normal. There were no abnormalities in sweating. History and family history was noncontributory. There was no history suggestive of systemic involvement. General physical examination showed normal vitals. His anterior hairline was receded and high. Child had coarse, dry, wiry hairs on the scalp standing out from the head. Sparse hair with partial alopecia was present on vertex, parietal and occipital region resembling androgenetic alopecia [Figure 1]. Eyebrows, eyelashes and body hair were sparse [Figure 2]. Palms, soles and oral mucosa were normal. Nails and teeth were normal. Systemic examination was normal. Light microscopy of the hair shaft revealed darkly pigmented irregular twisting with variable diameters [Figure 3]. Based on the clinical features, and characteristic pattern of hair loss diagnosis of MUHH was made. Genetic testing was not done due to its non-availability.

Figure 1

Coarse, wiry hair with patches of hair loss on vertex, parietal and occipital area resembling male pattern alopecia

Figure 2

Sparse eyebrows and eyelashes

Figure 3

Hair shaft showing darkly pigmented with irregular twisting on light microscopy

DISCUSSION

Hair abnormalities occur in children as an isolated phenomenon or as a part of genetic syndromes. MUHH is a rare autosomal dominant genodermatoses characterized by progressive non-scarring hair loss. This syndrome has been described in families in Germany, Europe, North America and China. It is reported more in Caucasians. The exact mechanism of hair loss is not known. It is suggested that genetic factors, altered hair shaft morphology, a decreased number of functional follicles and abnormal follicle cycling may contribute to the pathogenesis.[2] Mutation of the U2HR gene, located in chromosome 8p21 is responsible for MUHH. There are 17 mutations in U2HR gene identified until now in the literature from various ethnic backgrounds.[3] Our case was the only affected individual in the family and the possibilities of inheritance would be a de novo mutation, or the symptoms in one of the parents are minor only or there is a mutation in a so far unknown gene or it could be due to autosomal recessive from two obligate carriers.

Clinically affected individuals are born with sparse or absent hairs at birth, later there is regrowth of coarse, unruly hair in childhood and progressive, nonscarring loss of hair again at or nearing puberty.[4] There are few cases reported where there is normal to adequate hairs at birth that eventually develops into hair loss. There is receding of hair line with increasingly sparse hair on the vertex, parietal and occipital region resembling androgenetic alopecia.[5] Eyebrows, eyelashes, body hair and secondary sexual hair are sparse or absent. Eyebrow loss and presence of wiry, twisted hair is important for diagnosis.[6] Other ectodermal structures are normal. Diffuse follicular hyperkeratosis with milia-like facial lesions may be present. Some have reported association of MUHH with Ehlers-Danlos syndrome and juvenile macular degeneration which could be incidental findings.[78]

Multiple anagen hairs are extractable on gentle hair pull. Light microscopy of the hair shaft shows deeply pigmented, variations in shaft diameter, twisted and bent at odd angles that make it stand from the head. Longitudinal grooves and peeling of the cuticle are visible on scanning electron microscopy.[5] Histopathologically there are reduced numbers of follicles with mild to moderate inflammatory infiltrate. There is no fibrosis and scarring.

There is a lot of clinical overlap between various causes of isolated hereditary hypotrichosis. Differential diagnoses to be considered are alopecia universalis, congenital atrichia with papular lesions, hereditary hypotrichosis simplex and localized autosomal recessive hypotrichosis. Hereditary hypotrichosis simplex is characterized by normal hair growth at birth, but there is hair loss without hair shaft abnormalities. Autosomal recessive hereditary hypotrichosis is associated with sparse hairs, woolly hair, skin fragility, palmoplantar keratoderma, and cardiomyopathy.[910] There is no effective treatment available, and counseling should be done. The characteristic pattern of hair loss and twisted hair provides a clue to the diagnosis of MUHH.