XYLT2

Spondyloocular Syndrome

Clinical Characteristics
Ocular Features: 

Cataracts have been noted in several patients in the first and second decades of life.  Nystagmus and ‘amblyopia’ have also been reported.  Several individuals have had retinal detachments.

Systemic Features: 

Only a small number of families have been reported.  Poor bone mineralization with frequent fractures in long bones and vertebral compression seem to be consistent features often noted in the first and second decades of life.  Moderate osteoporosis and advanced bone age with platyspondyly may be present.  The vertebral fractures lead to abnormal spinal curvature and may result in shortened stature. 

Some sensorineural hearing loss is sometimes detected in the first decade.  The ears have been described as low-set and posteriorly rotated.  A variety of cardiac defects have been reported including mitral valve prolapse, septal defects, and anomalies of the aortic valve. 

Genetics

This is an autosomal recessive disorder secondary to homozygous mutations in the XYLT2 gene located at 17q21.33. 

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Pamidronate given intravenously seems to have little therapeutic value.  Hearing aids can be beneficial.  Lensectomy may be of benefit although no reports of cataract surgery have been reported.  Fractures need immediate attention.  Patient may become wheelchair-bound by the second decade.  Special education may be helpful for those with learning difficulties.

References
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