Xpter-q13.1 locus

Cataracts, Ataxia, Short Stature, and Mental Retardation

Clinical Characteristics
Ocular Features: 

Cataracts are present in both sexes but the opacification is more extensive in males and only partial in females.  The cataracts are congenital in males but apparently develop later in females who complain of blurred vision from early childhood or during teenage years.  The lenses in females have punctate and pulverulent opacities as well as posterior subcapsular sclerosis.  Vision has been estimated as hand motion from early childhood in boys and about 20/40 in females in the first two decades of life.

Systemic Features: 

Males have mild to moderate mental retardation, muscle hypotonia and weakness with postural tremor.  Their standing position is broad-based and they are unable to sit or stand otherwise without some support.  They are usually unable to walk unassisted.  Speech is dysarthric and its development is delayed.  Females are neurologically normal.

Genetics

A locus containing the disease allele at Xpter-q13.1 cosegregates with the cataract phenotype in both sexes.  The gene mutation has not been identified.  This can be called an X-linked recessive disorder with partial expression in heterozygous females.

Pedigree: 
X-linked recessive, carrier mother
X-linked recessive, father affected
Treatment
Treatment Options: 

Cataract surgery may be indicated in young females and may be beneficial in infant boys.

References
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