Unusual genotypic and phenotypic presentation in a patient with nail‐patella syndrome

Abstract

AbstractPurpose: Nail‐Patella syndrome (NPS) is an autosomal dominant hereditary disease. It is characterized by a mutation in the gene that codes for the transcription factor LMX1B located on chromosome 9q34, essential for proper development of the musculoskeletal, renal, nervous and ocular systems. At the ophthalmological level, alterations of the anterior segment, ocular hypertension and its possible progression to glaucoma stand out.Methods: 21‐year‐old male who presents from birth short stature, reduced muscle mass, hypoplastic patella, involvement of fingernails and toenails, and progressive kidney failure. His genetic study shows an homozygous mutation in the LMX1B gene with c.376G > A (p.Glu126Lys) variant. Ophthalmologically, there are no symptoms. On examination, visual acuity is 0.9 in both eyes. Biomicroscopy shows a wide anterior chamber, bilateral gerontoxon and the presence of frayed iris. Gonioscopy shows an open angle without alterations in its structures. The intraocular pressure (IOP) measured by Goldmann tonometer is 3 mmHg in the right eye and 4 mmHg in the left eye, which is maintained in subsequent visits. The ocular fundus reveals a physiological papilla in both eyes and no signs of glaucomatous involvement. The visual field, macular, papillary and anterior segment optical coherence tomography are compatible with normality.Conclusions: the patient presents a typical NPS but with ocular hypotension that is not clinically significant and the mutation is homozygous. The usual ocular alterations occur in the drainage structures of the aqueous humour that cause an increase in IOP to a variable degree. Although ciliary body hypoplasia with atrophy of the ciliary processes has been described in animal models, which would produce an absence or decrease in the production of aqueous humour, no human case with ocular hypotony has been described in the current literature.