Chinese researchers have produced an overview of Alport syndrome that looks at the genetic disease’s primary symptoms — from kidney disease to hearing problems and eye abnormalities — and current treatments.
Their report, “Renal, auricular, and ocular outcomes of Alport syndrome and their current management,” was published in the journal Pediatric Nephrology.
Kidney problems are a man feature of Alport, which is caused by mutations of genes that encode a protein called type IV collagen. Kidney disease is found in all men with Alport and 95 percent of women. Because of this, common markers of the disease are red blood cells and excess protein in urine.
Many patients will progress to end-stage kidney disease, the study reported. The age of the disease’s onset varies, depending on people’s genetic alterations.
An article titled “Clinical practice recommendations for the treatment of Alport syndrome” says the first-line therapy for the kidney problems stemming from Alport syndrome should be angiotensin-converting enzyme inhibitors, or ACEis. It says second-line therapies should be angiotensin receptor blockers, or ARBs, and aldosterone inhibitors. Such therapies are aimed at reducing that excess protein the kidneys send to the urine and at delaying kidney damage.
A transplant is the only cure for patients with end-stage kidney disease. Recent studies find that 70.2 percent of patients survive for at least 20 years after a transplant. This indicates that a transplant is a viable option for Alport patients with end-stage kidney disease.
Hearing loss and eye abnormalities and also associated with Alport, and can lead in rare cases to leiomyomatosis, or the development of benign smooth muscle tumors.
Hearing loss is a frequent symptom of the disease, found in about 73 percent of all patients, while eye abnormalities are detected in about 57 percent.
As with kidney symptoms, the age when hearing loss occurs depends on patients’ genetic mutations. But symptoms become evident, on average, in patients between 30 and 40 years old. Some researchers believe there is an association between hearing loss and kidney problems, with hearing loss considered a risk factor for kidney failure.
Alport-related eye problems include dot-and-fleck retinopathy, anterior lenticonus, and corneal dystrophy.
A hallmark of fleck retinopathy, which occurs in about 85 percent of patients, is small, yellowish dots in the retina that do not affect sight. In contrast, anterior lenticonus, or a deformed eye lens, and corneal dystrophy, a build-up of material on the cornea, can lead to visual impairment.
No therapies are available to manage the hearing or vision symptoms of Alport, the study noted. Hearing aids can help those with moderate hearing loss, while eye pads, antibiotics applied directly to the eyes, and pain relief medicines can help with optical symptoms. In severe cases, a corneal transplant or intraocular lens implant may be necessary.
“Progress in basic research is raising hopes of defining new targets for the treatment of Alport syndrome. Many potential treatment approaches in Alport syndrome have been revealed by animal models,” the researchers wrote.
Progress in stem cell and gene therapy are raising hopes of Alport treatments. So far, success at slowing or reversing Alport symptoms has occurred only in mice and pig models of the disease, however. These treatments are not ready for patients, the researchers said.
Several molecular studies have identified potential targets for therapies to prevent kidney fibrosis and inflammation. Targeting them has improved kidney function in mice.
But much work remains to be done, and more support for research is needed, the study concluded.
“To carry out clinical trials for Alport syndrome, multilateral collaborations are needed that include physicians, patient families, researchers, the pharmaceutical industry, and funding organizations,” the researchers wrote.