Björnstad syndrome

What is Björnstad syndrome?

Björnstad syndrome is a rare genetic disorder characterised by the hallmark features of pili torti (twisted hair) and congenital sensorineural hearing loss.

This condition is also referred to as deafness-pili torti-hypogonadism syndrome.

Who gets Björnstad syndrome?

Björnstad syndrome is an inherited condition that typically follows an autosomal recessive inheritance pattern, although autosomal dominant cases have also been reported. 
The condition is extremely rare — there are fewer than 50 cases reported globally, and the estimated incidence is less than 1 in 1,000,000. It does not appear to show any gender or racial predilection.

What causes Björnstad syndrome?

First described in 1965, Björnstad syndrome arises from mutations in the BCS1L gene located on chromosome 2q34-36. This gene is essential for the function of the mitochondrial electron transport chain, particularly in the assembly of complex III. Dysfunction leads to the accumulation of reactive oxygen species (ROS), which damage sensitive hair follicles and inner ear cells.

Mutations of the BCS1L gene can also cause GRACILE syndrome and complex III deficiency, both of which are severe, multisystem, autosomal recessive disorders.

What are the clinical features of Björnstad syndrome?

The two defining features of Björnstad syndrome are pili torti and sensorineural hearing loss, and they are usually evident by 2 years of age.

Cutaneous features

• Pili torti
  • Flat, twisted, brittle hair prone to breakage.
  • Typically only affects the scalp, though other areas are occasionally affected eg, eyebrow, eyelashes, body hair
• Lack of hair pigmentation
• Anhidrosis

Non-cutaneous features

• Sensorineural hearing loss
  • Typically bilateral
  • Impairment ranges from mild to severe
  • Impacts speech and language development
• Hypogonadism
• Intellectual disability

Short kinked hairs due to pili torti in Bjornstad syndrome 

Tortuous kinked hairs in Bjornstad syndrome 

How do clinical features vary in differing types of skin?

In individuals with darker Fitzpatrick skin types, the brittle nature of pili torti may be less visually apparent but still identifiable upon closer examination.

What are the complications of Björnstad syndrome?

• Alopecia or hair shedding.
• Progressive hearing loss
• Developmental delays
• Psychosocial distress

How is Björnstad syndrome diagnosed?

Björnstad syndrome is diagnosed based on clinical findings of pili torti and sensorineural hearing loss. Molecular genetic testing confirms BCS1L mutations. Supporting tests include:

• Audiometric assessments to determine sensorineural hearing loss.
• Microscopic hair examination for pili torti.
• Electron microscopy to detect characteristic twisting of hair shafts at regular intervals.

What is the differential diagnosis for Björnstad syndrome?

• Menkes disease
• Trichothiodystrophy
• Hypotrichosis-deafness syndrome
• Crandall syndrome

What is the treatment for Björnstad syndrome?

There is no cure for Björnstad syndrome, and management is centred on supportive and symptomatic treatment.

Measures include:

• Early intervention for hearing impairment eg, hearing aids, cochlear implants
• Educational support tailored to developmental needs
• Regular monitoring of hearing and hair changes
• Genetic counselling for affected families
• Symptomatic management of alopecia, including wigs or other hair replacement options.

How do you prevent Björnstad syndrome?

Björnstad syndrome is a genetic condition for which there is no known prevention. Genetic screening and counselling may help families assess risk factors and make an informed decision regarding family planning.

What is the outcome for Björnstad syndrome?

Björnstad syndrome entails a variable prognosis based on early detection and intervention. Management of hearing loss significantly improves development and quality of life. Hair abnormalities persist, though they can be managed with cosmetic solutions.