ADAMTSL4

Ectopia lentis, Isolated AR

Clinical Characteristics
Ocular Features: 

Most dislocated lenses of non-traumatic origin are associated with syndromes, particularly those with defective connective tissue.  However, a few families with dislocated lenses have been reported in which no evidence of defective collagen is present.  The lens is most commonly displaced temporally, often creating myopic astigmatism.  The mean age of discovery of the dislocated lenses is about 2 years of age.  The eye is otherwise normally formed, intraocular pressure is normal, and the axial length is in the normal range.  The cornea, pupil, and iris are normal unlike that found in many patients with ectopia lentis et pupillae (225200).

Systemic Features: 

None by definition.

Genetics

Homozygous nonsense mutations in ADAMTSL4 (1q21.3) are responsible for this autosomal recessive condition.  The same gene is mutated in ectopia lentis et pupillae (225200).  A patient has been reported with craniosynostosis and ectopia lentis in which there was a homozygous 20 bp deletion in this gene.

An autosomal dominant condition of isolated dislocated lenses (129600) secondary to a mutation in FBN1 has also been reported.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Lens removal may be indicated when vision cannot otherwise be corrected.

References
Article Title: 

Ectopia Lentis et Pupillae

Clinical Characteristics
Ocular Features: 

This disorder is generally considered to consist of simple displacement of the pupil and dislocation of the lens (usually in opposite directions).  However, other abnormalities are often present such as persistent pupillary membrane (87%), iridohyaloid adhesions, increased corneal thickness, enlarged corneal diameters, and axial myopia.  The iris may transilluminate (67%) and the pupils dilate poorly.  Iridodenesis is common (85%).  The lens is often malformed and in some cases frankly microspherophakic.  The lens displacement can progress and cataracts seem to form at a relatively young age.  Visual acuity is highly variable, ranging from 20/20 to light perception depending upon the density of cataracts which often develop at a relatively young age. Prominent iris processes into the anterior chamber angle have been reported and glaucoma, both acute and chronic, is sometimes seen.  Retinal detachment is a risk.

Studies in families with ectopia lentis et papillae have revealed that as many as 50% of individuals with dislocated lenses do not have ectopic pupils.

Systemic Features: 

None reported

Genetics

This disorder is usually inherited in an autosomal recessive pattern.  Multiple affected sibs have been born to consanquineous matings.  However, other families in which detailed ophthalmological examinations were done have suggested dominant inheritance based upon the presence of more subtle ocular signs in relatives.  This is likely a more clinically heterogeneous disorder than has been appreciated.

In five Norwegian families a homozygous 20 bp deletion has been found in the gene ADAMTSL4 on chromosome 1 (c.767_786del20) (1q21.3) producing a frameshift and the introduction of a stop codon leading to truncation of the protein product.  Mutations in the same gene have also been found in the autosomal recessive form of isolated ectopia lentis (225100).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Glaucoma, retinal detachments, and cataracts may require surgery.

References
Article Title: 
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