Sponastrime dysplasia

Sponastrime dysplasia is a rare condition characterised by facial and skeletal abnormalities.

Sponastrime dysplasia
This condition is inherited in an autosomal recessive manner.
Specialty	Medical genetics
Causes	Mutations in the TONSL gene

Signs and symptoms

The main features of this condition are evident in skeleton and face.

Facial features:

• Macrocephaly
• Frontal bossing
• Midface hypoplasia
• Depressed nasal root
• Small upturned nose
• Prognathism

Skeletal features:

• Shortened limbs (more pronounced in lower limbs)
• Short stature
• Progressive coxa vara

On X ray:

• Abnormal vertebral bodies (particularly in the lumbar region)
• Avascular necrosis of the capital femoral epiphyses
• Striated metaphyses
• Generalized mild osteoporosis
• Delayed ossification of the carpal bones

Other associated conditions:

These are variably present

• Cataracts
• Hypogammaglobulinemia
• Intellectual disability
• Short dental roots
• Subglottic stenosis
• Tracheobronchomalacia

Genetics

This condition has been associated with mutations in the Tonsoku-like, DNA repair protein (TONSL) gene. This gene is located on the long arm of chromosome 8 (8q24.3). This gene is also known as NFKBIL2.

Pathopysiology

This is not understood. It appears that the TONSL gene product is involved in genome repair.

Diagnosis

This can be suspected when the usual facial and skeletal features are present. It is confirmed by sequencing the TONSL gene.

Differential diagnosis

Short limbed dwarfism syndrome in association with immunodeficiency.

Treatment

There is no specific treatment for this condition. Management is supportive.

Epidemiology

This condition is considered to be rare with less than 100 cases reported in the literature.

History

This condition was first described in 1983.