OMIM ID:
Sulfite Oxidase Deficiency
Alternate Names
Defective Genes
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
Inheritance
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.
Pedigree
Autosomal recessive
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.