Case Reports

Delayed diagnosis of homocystinuria presenting as bilateral congenital lens subluxation

Case Report Details

First Author: M.Jelic Vukovic CROATIA

Co Author(s):    S. Matić   D. Biuk   J. Barač   I. Pivić Kovačević           

Abstract Details

Purpose:

Homocystinuria is an autosomal recessively inherited defect in methatione metabolism leading to hyperhomocysteinemia. It is associated with mental retardation, seizures, marfanoid habitus and ocular manifestations, mainly myopia and ectopia lentis. It has an estimated incidence of 1:50 000 – 200 000, sufficiently high to consider it for screening in newborns. After the condition is suspected based on physical findings, personal and family history, workup is done for confirmation, including measuring homocysteine levels in blood and urine. Neonatal screening tests used for testing other similar metabolic disorders lack sensitivity in detecting homocystinuria.

Setting:

A 26-year old Caucasian male was referred to the Department of vitreoretinal surgery. Reason of referral was need of surgical treatment of a subluxated lens that had caused secondary glaucoma. At the age of two he underwent a left nephrectomy and subsequent chemotherapy due to Wilms tumor.

Report of Case:

The patient was referred to an internal medicine specialist. He underwent a physical examination and a complete ophthalmologic examination. Routine laboratory tests were ordered, including plasma homocysteine measurement. Homocysteine level was 15 μmol/L. Systemic signs and elevated and elevated homocysteine levels suggested homocysteinema as the most probable underlying condition. Blood dyscrasias, Fabry disease and acidemias were ruled out, since there was no history of thromboembolic events and coagulation studies were normal. He was administered timolol/dorzolamide, brimonidine and latanoprost in order to relieve elevated intraocular pressure. Since secondary bilateral glaucoma was unresponsive to treatment, a bilateral pars plana lensectomy and vitrectomy followed by a sulcus fixation of the intraocular lens (ALCON MA60 Acrysof IOL) were performed. As well, a therapeutic regimen was established consisting of folic acid (5 mg/day), cobalamine (1 mg /week), pyridoxine (900 mg/day), and a methionine restricted diet. Three months upon the initiation of therapy, homocysteine levels were reduced to 10 μmol/L. Ophthalmologic examination showed cIOL 0.1 LogMAR in the right eye, cIOL 0.3 LogMAR in the left eye, and normal values of IOP.

Conclusion/Take Home Message:

Early detection are of paramount importance in homocystinuria patients. Timely interventions can reduce number of complications. Abnormaly high and progressive myopia at young age combined with systemic complications are signs of suspected homocystinuria. Nevertheless, significant delays in diagnosis occur, as was the case with our patient. EL occurs in around 80% of patients and it is the most common involvement in homocystinuria (7,8). About 70% of patients will develop EL by 8 years of age, and 82% by the age of 10 (9). Even though EL is one of the most prominent symptoms of homocystinuria, and 5% of all lens dislocations may be attributed to this metabolic condition, homocystinuria is often neglected in the differential diagnosis of EL which leads to a delay in, or lack of, correct diagnosis and treatment. Every EL requires a broad differential diagnostic approach since it is often a presentation of systemic disease.

Financial Disclosure:

None