Sjögren-Larsson syndrome

Sjögren-Larsson syndrome is a rare inherited disorder affecting the skin and nervous system of variable severity.

The most common symptoms and signs are:

• ichthyosis (dry skin)
• spastic diplegia or tetraplegia (forms of cerebral palsy)
• intellectual impairment.

What is the cause of Sjögren-Larsson syndrome?

Sjögren-Larsson syndrome is caused by an inborn error of metabolism resulting in the deficiency of an enzyme, fatty aldehyde dehydrogenase, which is needed to produce normal oils and fats in the body. Deficient oxidation of medium and long chain fatty aldehydes into fatty acids results in abnormal fats in the skin and nervous system.

Sjögren-Larsson syndrome has an autosomal recessive inheritance; that is, affected individuals have two abnormal genes, one from each parent.The responsible gene is the FALDH gene found on chromosome 17. Over 70 mutations in this gene resulting in this disorder have been identified.

Clinical features

Skin

• Red, dry skin from birth
• The collodion baby presentation has been described but is unusual
• Scaling develops after infancy
• Neck, lower abdomen and large folds are most involved
• Thick skin of palms and soles (palmoplantar keratoderma) in 70%
• Itching and scratching
• Heat intolerance

Neurological

• Glistening white dots on retina are often detectable in the first year of life
• Delayed motor development (muscles)
• Abnormal gait
• Paresis (weak muscles)
• Spasticity (muscle stiffness and spasms)
• May affect legs and/or arms
• Delayed speech
• Intellectual impairment
• Seizures (epilepsy) in 40%

Other

Alteration of posture and gait leads to:

• Kyphoscoliosis (abnormal curvature of the spine)
• Hip dislocation
• Short stature
• Learning disability
• Photophobia (avoidance of exposure to bright light)

Diagnosis

The diagnosis of Sjogren-Larsson syndrome is usually made clinically. It may be confirmed in some centres by measurement of fatty aldehyde dehydrogenase in white blood cells or cultured fibroblasts collected by skin biopsy.

Known gene mutations can now be identified in some centres.

Management

Management should be multidisciplinary with input from speech language therapy, physiotherapy, occupational therapy, dermatology, neurology, ophthalmology and orthopaedic services.

Skin hydration is important so emollients and moisturisers should be applied to dry skin regularly. Topical keratolytics such as urea and lactic acid (see fruit acids) can reduce scale and skin thickening.

Severe ichthyosis is sometimes treated with systemic retinoids such as acitretin or isotretinoin.