What is Sjögren-Larsson syndrome?
Sjögren-Larsson syndrome is a rare inherited disorder that affects the skin and nervous system.
The most common symptoms and signs are variable degrees of:
- 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 (FALDH), 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 ALDH3A2 gene found on chromosome 17, which encodes FALDH. Over 70 mutations in this gene resulting in this disorder have been identified.
What are the clinical features of Sjogren-Lasson syndrome?
- Children with Sjögren-Larsson syndrome have red, dry skin from birth.
- Presentation as a collodion baby has been described, but it is unusual.
- Scaling more usually develops after infancy.
- The neck, lower abdomen and large folds are most involved.
- Thick skin of the palms and soles (palmoplantar keratoderma) affects 70% of patients
- Itching and scratching is common.
- Heat intolerance may arise.
- Glistening white dots on the retina are often detectable in the first year of life.
- Delayed motor development (muscles) of legs and/or arms is noted in childhood. It results in:
- Abnormal gait
- Paresis (weak muscles)
- Spasticity (muscle stiffness and spasms).
- Children may have speech delay and intellectual impairment.
- Seizures (epilepsy) affect 40% of children with Sjögren-Larsson syndrome.
Other features of Sjögren-Larsson syndrome
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).
How is Sjögren-Larsson syndrome diagnosed?
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 of Sjögren-Larsson syndrome
Management of Sjögren-Larsson syndrome should be multidisciplinary with input from speech and language therapy, physiotherapy, occupational therapy, dermatology, neurology, ophthalmology and orthopaedic services.
Skin hydration is important; 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. New products specifically aimed at the treatment of Sjögren-Larsson syndrome are under investigation.
Severe ichthyosis is sometimes treated with oral retinoids such as acitretin or isotretinoin.