Renal-Coloboma Syndrome

At a glance

A rare familial syndrome combining optic nerve colobomas, vesicoureteral reflux, and renal dysplasia.

Synonyms

Papillorenal Syndrome; Optic Nerve Coloboma with Renal Disease; Optic Coloboma, Vesicoureteral Reflux, Renal Anomalies Syndrome; Coloboma-Ureteral-Renal Syndrome.

History

First described by American ophthalmologist R. G. Weaver in 1988.

Incidence

Rare.

Genetic inheritance

Autosomal dominant. Less than 200 patients in 90 different families have been reported.

Pathophysiology

Mutations in the PAX2 gene (a transcription factor known to play a critical role in embryogenesis and to be expressed in the developing eye, ear, kidney, ureteric bud, and midbrain/hindbrain) located on 10q24.3-q25.1 lead to colobomatous eye defects.

Clinical aspects

Ophthalmic and renal anomalies of this syndrome are most often bilateral, but highly variable. Developmental abnormalities of the optic fissure result in a group of defects including orbital cysts, microphthalmia, optic disc dysplasia, and colobomas of the optic nerve (sometimes referred to as “Morning Glory Disc Anomaly”) and retina at the posterior pole of the globe. (Iris colobomas have not been observed in patients with mutations in PAX2). Optic nerve colobomas involve the optic nerve head or optic papilla, and also result in thinning of the surrounding retinal epithelium, causing congenital blindness or loss of visual acuity, although not all patients with optic nerve colobomas have visual defects. Progressive deterioration of visual acuity over several decades has been described. The kidneys often appear small. The degree of renal disease is very variable, but the disease is usually progressive and often requires dialysis and/or renal transplant (although the age at end-stage renal disease is very variable). Patients with basically normal renal function have also been described. Renal biopsies may demonstrate mesangial fibrosis, glomerulosclerosis, glomerular hyalinization, hyperplastic glomeruli, tubular atrophy, and an overall rarefaction of glomeruli. Pathological examination of kidneys may find cortical thinning, hypoplastic papillae, a decreased number of glomeruli in the cortex and collecting ducts in the papilla, consistent with renal hypoplasia. Vesicoureteral reflux (VUR) is common in these children; however, it is not known to which extent VUR is responsible for the kidney changes described above. Some of these patients may also suffer from high-frequency hearing loss, central nervous system anomalies (seizure disorder, ☞Arnold Chiari Syndrome Type I), joint laxity, and genital anomalies (cryptorchidism).

Anesthetic considerations

Preoperative laboratory investigations should include a full blood count (FBC) (renal anemia), serum electrolytes, serum albumin (proteinuria), creatinine, and blood urea nitrogen. In case of end-stage renal disease, ask about the date of the last hemodialysis, residual urine production, and the daily maximal allowable amount to drink. Avoid potassium-containing intravenous solutions in these patients. Chronic antiepileptic treatment may interfere with the metabolism and elimination ...