OMIM ID:
Kahrizi Syndrome
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
In an Iranian family with 3 affected sibs, cataracts (not further characterized) were noted in late adolescence. Iris colobomas, unilateral in one sib and bilateral in another, were present.
Systemic Features
Children have severe psychomotor delays from birth and have severe mental retardation. Speech and normal motor function never develop fully. Thoracic kyphosis begins in late childhood and contractures develop in the elbows and knees. A CAT scan in one patient revealed only normal findings. Facial features have been described as ‘coarse’ with prominent lips, broad nasal bridge, and a bulbous nose. Some individuals with this condition have lived into the 5th decade. Ataxia is usually present although the cerebellum may be normal on MRI.
Genetics
Inheritance
This is an autosomal recessive condition resulting from homozygous mutations in the SRD5A3 gene (4q12).
Kahrizi syndrome is allelic to CDG1Q, or congenital disorder of glycosylation type Iq (612379), an autosomal recessive disorder with mutations in the same gene and a partially overlapping ocular phenotype.
At least 10 families have been reported with mutations in this gene considered important to glycosylation.
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.