Sulfite Oxidase Deficiency

Clinical Characteristics
Ocular Features: 

Dislocated lenses are the only significant ocular features of this disorder.  In one patient the lenses were said to be in normal position at 5.5 months of age but mild nasal subluxation of both lenses was present at 11 months.  In a series of 22 patients, 10 had dislocated lenses and one had spherophakia.  Lens dislocations occur early and maybe even congenitally in some cases as the diagnosis has been made in seven children before one year of age.  On the other hand it is not a consistent sign since the lenses were not dislocated in seven individuals who were examined specifically for this sign.

Systemic Features: 

Outside of the eye, the main features of this disorder are secondary to neurological damage.  Symptoms of irritability, poor feeding, ataxia, and language development may be seen in the first year or two of life.  Respiratory distress can be a feature in neonates.  Hypotonia, dystonia and choreoathetosis may be seen as well.  Seizures (sometimes with opisthotonus) often occur in the first days or weeks of life.  Later, generalized hypertonia and hyperactive reflexes are present.  Global developmental delays occur in nearly 80% of patients.  However, some patients also have a later onset with a milder course indicating that the full range of clinical expression remains to be determined.

Genetics

A number of mutations in the SUOX gene on chromosome 12 (12q13.13) cause this rare autosomal recessive disorder.  Less than 50 cases have been reported worldwide.

Treatment
Treatment Options: 

Not enough patients have been evaluated for long enough to determine the optimum treatment but low protein diets and restriction of sulfur containing amino acids have been tried with mixed results.

References
Article Title: 

References

Johnson JL, Coyne KE, Garrett RM, Zabot MT, Dorche C, Kisker C, Rajagopalan KV. Isolated sulfite oxidase deficiency: identification of 12 novel SUOX mutations in 10 patients. Hum Mutat. 2002 Jul;20(1):74.

PubMedID: 12112661

Shih VE, Abroms IF, Johnson JL, Carney M, Mandell R, Robb RM, Cloherty JP, Rajagopalan KV. Sulfite oxidase deficiency. Biochemical and clinical investigations of a hereditary metabolic disorder in sulfur metabolism. N Engl J Med. 1977 Nov 10;297(19):1022-8.

PubMedID: 302914

Tan WH, Eichler FS, Hoda S, Lee MS, Baris H, Hanley CA, Grant PE, Krishnamoorthy KS, Shih VE. Isolated sulfite oxidase deficiency: a case report with a novel mutation and review of the literature. Pediatrics. 2005 Sep;116(3):757-66. Review. Erratum in: Pediatrics. 2005 Dec;116(6):1615.

PubMedID: 16140720