Spondylometaphyseal Dysplasia, Axial

Clinical Characteristics
Ocular Features: 

Due to the small number of individuals reported, the ocular phenotype is variable and likely incompletely described.  Optic atrophy and pigmentary retinopathy are the most consistent findings.  The most completely studied individual had evidence of slight bilateral optic nerve atrophy on cerebral MRI imaging as well.  There may be extensive RPE atrophy but the fundus pigmentation is usually described as resembling retinitis pigmentosa.  The ERG in several patients during the second decade of life already shows severe dysfunction of the photoreceptors, with cones the most severely impacted.  In spite of this Goldmann visual fields have been reported to be normal.  The macula and OCT have been reported as normal.  Telecanthus, nystagmus, hypertelorism, proptosis, and photophobia have been reported.  Early onset and progressive visual impairment are characteristic.

Systemic Features: 

Only 5 patients with this condition have been reported most of whom were short in stature.  There may be frontal bossing and the chest is narrow and flattened.  Moderate platyspondyly has been described with enlarged but shortened ribs and an irregular iliac crest.  Rhizomelic shortening of the limbs is common.  The femoral metaphyses are abnormal with their necks shortened and enlarged.  The ribs are enlarged but shortened as well and are flared at the ends.  Mental development and function are normal.

Genetics

This is an autosomal recessive condition due to homozygous or compound heterozygous mutations in C21orf2.

Treatment
Treatment Options: 

No effective treatment is known.

References
Article Title: 

Axial Spondylometaphyseal Dysplasia Is Caused by C21orf2 Mutations

Wang Z, Iida A, Miyake N, Nishiguchi KM, Fujita K, Nakazawa T, Alswaid A, Albalwi MA, Kim OH, Cho TJ, Lim GY, Isidor B, David A, Rustad CF, Merckoll E, Westvik J, Stattin EL, Grigelioniene G, Kou I, Nakajima M, Ohashi H, Smithson S, Matsumoto N, Nishimura G, Ikegawa S. Axial Spondylometaphyseal Dysplasia Is Caused by C21orf2 Mutations. PLoS One. 2016 Mar 14;11(13).

PubMed ID: 
26974433

Axial spondylometaphysealdysplasia

Ehara S, Kim OH, Maisawa S, Takasago Y, Nishimura G. Axial spondylometaphysealdysplasia. Eur J Pediatr. 1997 Aug;156(8):627-30.

PubMed ID: 
9266195

References

Wang Z, Iida A, Miyake N, Nishiguchi KM, Fujita K, Nakazawa T, Alswaid A, Albalwi MA, Kim OH, Cho TJ, Lim GY, Isidor B, David A, Rustad CF, Merckoll E, Westvik J, Stattin EL, Grigelioniene G, Kou I, Nakajima M, Ohashi H, Smithson S, Matsumoto N, Nishimura G, Ikegawa S. Axial Spondylometaphyseal Dysplasia Is Caused by C21orf2 Mutations. PLoS One. 2016 Mar 14;11(13).

PubMedID: 26974433

Isidor B, Baron S, Khau van Kien P, Bertrand AM, David A, Le Merrer M. Axial spondylometaphyseal dysplasia: Confirmation and further delineation of a new SMD with retinal dystrophy. Am J Med Genet A. 2010 Jun;152A(6):1550-4.

PubMedID: 20503334

Ehara S, Kim OH, Maisawa S, Takasago Y, Nishimura G. Axial spondylometaphysealdysplasia. Eur J Pediatr. 1997 Aug;156(8):627-30.

PubMedID: 9266195