Indian Journal of Human Genetics Medknow Publications on behalf of Indian Society of Human Genetics ISSN: 0971-6866 EISSN: 1998-362x Vol. 12, Num. 2, 2006, pp. 99-99

Indian Journal of Human Genetics, Vol. 12, No. 2, May-August, 2006, pp. 99

Letter To Editor

Ocular abnormalities in nail patella syndrome

Raja Vignesh, Sandanshiv Pravin, Neugebauer Mark, Sweeney Elizabeth, McIntosh Iain

The School of Clinical Sciences, The University of Liverpool, Liverpool
Correspondence Address:The School of Clinical Sciences, The University of Liverpool, 69 Daulby Street, Liverpool L69 3GA, Email: drvigneshraja@gmail.com

Code Number: hg06018

Sir,

Nail patella syndrome (NPS; OMIM #161200) is a pleiotropic condition, with a classical clinical tetrad of involvement of the nails, knees, elbows and the presence of iliac horns. Kidney disease and glaucoma are now recognized as part of the syndrome.[1] We would like to report on the spectrum of ocular manifestations in patients with nail patella syndrome that have not been reported earlier.

In an observational case series study, we studied the eyes of seven patients with genetically confirmed nail patella syndrome. Examination included estimation of visual acuity, anterior segment examination using slit lamp, fundus examination with slit lamp biomicroscopy, applanation tonometry and gonioscopy.

In this initial study, all our patients were noted to have anterior chamber angle abnormalities, which comprised of prominent strands of iris tissue processes attached to the trabecular meshwork, with open angles, leading us to suspect a variant of Axenfeld's type of anomaly in patients with nail patella syndrome. Lester sign, which is a zone of darker pigmentation of cloverleaf or flower shape pattern in the central iris, was observed bilaterally in three patients. Four of the seven patients were known glaucomatous patients and were already on topical medication.

The findings of our study prompt us to wonder whether the ocular features of nail patella syndrome belong to the spectrum of anterior chamber cleavage syndromes, as a variation of Axenfeld's type of anomaly has clearly been demonstrated in the anterior chamber angle. Lester sign in the iris, though not pathognomonic, occurs more frequently in patients with NPS, as described in a study of 123 British patients.[2] Our study also highlights the increased incidence of glaucoma in patients with nail patella syndrome. This study emphasizes the need for regular screening of patients with nail patella syndrome for glaucoma.
Genetic analysis of these patients showed an abnormality in the LMX1B gene on chromosome 9q34. LMX1B is also expressed in the anterior chamber of the developing eye and in the kidney throughout life, explaining the findings of glaucoma and kidney disease in NPS patients.[1] The variation in symptoms among people with NPS is not believed to be associated with the different mutations found in LMX1B but may be the result of variation in the genes with which LMX1B interacts. Further studies with a larger group of patients with nail patella syndrome are needed to prove whether the angle abnormalities as demonstrated in our study actually contribute to the development of glaucoma.

References

Copyright 2006 - Indian Journal of Human Genetics