CASE RECORDS of the Massachusetts General Hospital; case 43511

Lenticonus anterior and Alport's syndrome

Six patients, from five families, five males and one female, suffering from lenticonus anterior are presented. Furthermore, all suffered from chronic nephritis and nerve deafness and must be considered cases of Alport's syndrome. As all cases with lenticonus anterior which have been published within the last 13 years likewise were affected with nerve deafness and/or chronic nephritis, the assumption is submitted that lenticonus anterior exists exclusively as a part of Alport's syndrome. It is pointed out that four patients had a weakened bilateral macula reflex with changes in pigmentation. Attention is drawn to the fact that patients with lenticonus anterior often have a cornea astigmatism of 2-3 D. A complete table of all reported patients with anterior lenticonus is presented.

Alport syndrome. A review of the ocular manifestations

Alport syndrome has a prevalence of 1/5000, and 85% of patients have the X-linked form, where affected males develop renal failure and usually have a high-tone sensorineural deafness by the age of 20. The typical ocular associations are a dot-and-fleck retinopathy which occurs in about 85% of affected adult males, anterior lenticonus which occurs in about 25%, and the rare posterior polymorphous corneal dystrophy. The retinopathy and anterior lenticonus are not usually demonstrated in childhood but worsen with time so that the retinal lesion is often present at the onset of renal failure, and the anterior lenticonus, later. The demonstration of a dot-and-fleck retinopathy in any individual with a family history of Alport syndrome or with end-stage renal disease is diagnostic of Alport syndrome. The presence of anterior lenticonus or posterior polymorphous corneal dystrophy in any individual is highly suggestive of the diagnosis of Alport syndrome. Additional ocular features described in X-linked Alport syndrome include other corneal dystrophies, microcornea, arcus, iris atrophy, cataracts, spontaneous lens rupture, spherophakia, posterior lenticonus, a poor macular reflex, fluorescein angiogram hyperfluorescence, electrooculogram and electroretinogram abnormalities, and retinal pigmentation. All mutations demonstrated to date in X-linked Alport syndrome have affected the COL4A5 gene which encodes the alpha 5 chain of type IV collagen. This protein is probably common to the basement membranes of the glomerulus, cochlea, retina, lens capsule, and cornea. However, the alpha 3(IV) and 4(IV) as well as the alpha 5(IV) collagen chains are usually absent from the affected basement membranes, because the abnormal alpha 5(IV) molecule interferes with the stability of all three. The loss of these collagen molecules from the affected basement membranes results in an abnormal ultrastructural appearance. The ocular and other clinical features of autosomal recessive Alport syndrome are identical to those seen in X-linked disease, while retinopathy and cataracts are the only ocular abnormalities described in the rare autosomal dominant form of Alport syndrome. There are no ocular associations of thin basement membrane disease which is a common disease that probably represents the heterozygous expression of X-linked or autosomal recessive Alport syndrome.

Macular flecks in a 5-year-old boy with Alport's syndrome

We examined a Japanese family with Alport's syndrome; four members of family showed hematuria or renal failure and two had a hearing disturbance. The proband was a 5-year-old boy who had hematuria but normal renal function and yellow-white flecks in the perimacular region of both eyes.

Ocular manifestations of Alport's syndrome: a hereditary disorder of basement membranes?

The ocular manifestations in 16 patients with Alport's syndrome were lenticonus and retinal flecks in the macula and mid periphery. These 3 features appear to be specific for this syndrome and are a considerable aid to diagnosis. Lens opacities are common, and other ocular abnormalities occur sporadically. The present evidence indicates that this is a hereditary, widespread disorder of basement membrane, and it is suggested that ophthalmologists may contribute to the further understanding of it by directing attention towards analysis of the lens capsule after cataract extraction. The similarity of the retinopathy to that of fundus albipunctatus is noted, and it is suggested that the latter condition should not be diagnosed in the absence of renal investigation and audiometry.