Renal diagnosis without renal biopsy. Nephritis and sensorineural deafness

Defining renal phenotype in Alström syndrome

BACKGROUND

Alström syndrome (AS) is a rare autosomal recessive ciliopathy with a wide spectrum of clinical features, including cone-rod retinal dystrophy, neuronal deafness, severe insulin resistance and major organ failure. The characteristics of renal disease in the syndrome have not been systematically described. The aim of this study is to define the onset and progression of renal disease in AS.

METHOD

Prospective observational cohort study.

SETTING AND PARTICIPANTS

Thirty-two adult subjects from a national specialist clinic in UK and 86 subjects from an international AS registry were studied.

OUTCOMES

First, an international registry cross-sectional study across all age groups to determine change in kidney function was performed. Secondly, a detailed assessment was carried out of adult AS patients with serial follow-up to determine incidence, aetiology and progression of renal disease.

ANALYTICAL APPROACH

Generalized estimating equations were used to evaluate the relationship between age and estimated glomerular filtration rate (eGFR). Associations between patient factors and eGFR levels were then assessed in the adult AS cohort.

RESULTS

The international registry study of the renal function of 118 subjects with AS (median age 21 years) showed a rapid decline with age, at an average of -16.7 and -10.9 mL/min/1.73 m2 per decade in males and females, respectively. In a UK national cohort of 32 patients with AS (median age 22 years), 20/32 (63%) had chronic kidney disease (CKD) Stage 3 or above based on eGFR <60 mL/min/1.73 m2 or evidence of albuminuria. Hyperuricaemia was noted in 25/32 (79%). Structural abnormalities such as nephrocalcinosis without hypercalcaemia and cysts were observed in 20/32 (63%) subjects. Lower urinary tract symptoms were frequent in 17/19 (70%) of AS patients. Histological evidence showed mixed tubulo-interstitial and glomerular disease.

CONCLUSIONS

This is the first study to demonstrate that renal disease is the hallmark of AS, which starts early and progresses with age, leading to a high prevalence of advanced CKD at young age. AS should be considered in the differential diagnosis of rare genetic renal diseases.

Alström syndrome: genetics and clinical overview

Alström syndrome is a rare autosomal recessive genetic disorder characterized by cone-rod dystrophy, hearing loss, childhood truncal obesity, insulin resistance and hyperinsulinemia, type 2 diabetes, hypertriglyceridemia, short stature in adulthood, cardiomyopathy, and progressive pulmonary, hepatic, and renal dysfunction. Symptoms first appear in infancy and progressive development of multi-organ pathology leads to a reduced life expectancy. Variability in age of onset and severity of clinical symptoms, even within families, is likely due to genetic background.Alström syndrome is caused by mutations in ALMS1, a large gene comprised of 23 exons and coding for a protein of 4,169 amino acids. In general, ALMS1 gene defects include insertions, deletions, and nonsense mutations leading to protein truncations and found primarily in exons 8, 10 and 16. Multiple alternate splice forms exist. ALMS1 protein is found in centrosomes, basal bodies, and cytosol of all tissues affected by the disease. The identification of ALMS1 as a ciliary protein explains the range of observed phenotypes and their similarity to those of other ciliopathies such as Bardet-Biedl syndrome.Studies involving murine and cellular models of Alström syndrome have provided insight into the pathogenic mechanisms underlying obesity and type 2 diabetes, and other clinical problems. Ultimately, research into the pathogenesis of Alström syndrome should lead to better management and treatments for individuals, and have potentially important ramifications for other rare ciliopathies, as well as more common causes of obesity and diabetes, and other conditions common in the general population.

Alport syndrome: significance of gingival biopsy in the initial diagnosis and periodontal evaluation after renal transplantation

Alport Syndrome (AS) is an important hereditary disorder affecting the glomerular basement membrane. Diagnosis of AS is based on the presence of hematuric nephropathy, renal failure, hearing loss, ocular abnormalities and changes in the glomerular basement membrane of the lamina densa. The aims of this case report were to show the changes in the gingival tissues in a patient with AS under therapy with cyclosporin-A after renal transplantation and to discuss the possible role of type IV collagen in gingival basal lamina as an alternative approach for the diagnosis of AS. A 20-year-old male patient with AS underwent periodontal therapy including a series of gingivectomy surgeries. Gingival samples obtained during the second surgery were examined histopathologically and by transmission electron microscopy for further pathological examination. Gingivectomy procedures have been performed every 6 months over the last 4 years. The excessive and fibrous gingival enlargements resulted in migration of the anterior teeth, but no alveolar bone loss occurred. This is the first report to demonstrate the possible changes in the gingival tissues caused by AS. It is suggested that gingival biopsy can be an initial diagnostic tool instead of renal or skin biopsies. Proper dental and periodontal care and regular visits to the dentist could provide limited gingival hyperplasia to patients with AS.

A mild form of Alstrom disease associated with metabolic syndrome and very high fasting serum free fatty acids: two cases diagnosed in adult age

Alstrom syndrome (ALMS) is a very rare genetic autosomal recessive disease, characterized by early-onset severe abdominal obesity, impaired glucose tolerance or type 2 diabetes with insulin resistance, acanthosis nigricans, hyperlipidemia, childhood progressive retinal degeneration or retinitis pigmentosa and neurosensory hearing loss or deafness, cardiomyopathy, and other endocrine disorders. Genetic studies locate the ALMS gene on chromosome 2p12-13. The aim of this paper is to describe and discuss two unrelated cases of a mild ALMS form diagnosed after the age of 40 and 60, respectively, in adult fertile female patients. These cases showed several features of the disease plus other alterations characteristic of the classic "metabolic syndrome," including hypertension, hyperfibrinogenemia, and thrombotic states. Moreover, the patients had very high fasting serum free fatty acid (FFA) levels (2150 and 1919 micromol/L, respectively), which proved to be sensitive to inhibition by oral glucose tolerance test (OGTT)-induced hyperinsulinemia as well as to caloric restriction. ALMS may have an adverse prognosis and is often underdiagnosed. Its mild form, which allows a long survival, may also be associated with the late complications of the metabolic syndrome, leading to increased vascular risk.