Ochronosis of the aortic valve

Black aortic valve and coronary arteries in liver transplantation patient: case report

Background

Black pigmentation of the aortic valve and coronary arteries has been reported to be caused by alkaptonuria or minocycline. In patients with liver transplantation it has been described only once, after exposure to minocycline. We report a second case of such pigmentation in a liver transplantation patient, for whom none of the known causes are an adequate explanation for this pigmentation.

Case presentation

Our 56-year-old male patient showed a complex history of two liver transplantations and sleeve gastrectomy, and had neither alkaptonuria nor a history of minocycline intake. He underwent an urgent coronary bypass grafting and aortic valve replacement because of an acute coronary syndrome based on three-vessel disease and progressive aortic valve stenosis. During this procedure, the aortic valve and coronary arteries had black pigmentation.

Conclusions

There are causes – other than alkaptonuria and minocycline – that can induce a black pigmentation of the aortic valve and coronary arteries. In patients with a history of liver transplantation, alteration in (dys)functional liver parenchyma or administration of substances related to the procedure of liver transplantation are possible causes. Identifying these is important because they are potentially harmful as they may induce degenerative changes and functional impairment of the aortic valve and coronary arteries. Further research is needed, but proves to be difficult due to the rare nature of this condition.

A novel mutation in the homogentisate 1,2 dioxygenase gene identified in Chinese Hani pediatric patients with Alkaptonuria

BACKGROUND

Alkaptonuria (AKU) is a rare tyrosine metabolism disorder caused by homogentisate 1,2-dioxygenase (HGD) mutations and homogentisic acid (HGA) accumulation. In this study, we investigated the genotype-phenotype relationship in AKU patients with a novel HGD gene mutation from a Chinese Hani family.

METHODS

Routine clinical examination and laboratory evaluation were performed, urine alkalinization test and urinary gas chromatography-mass spectrometry were used to assess HGA. Gene sequencing was utilized to study the defining features of AKU. NetGene2-2.42 and BDGP software was used to predict protein structure online. Flow cytometry and RT-PCR were used to analyze HGD proteins and HGD mRNA, respectively.

RESULTS

Two pediatric patients fulfilled diagnostic criteria for AKU with eddish-brown or black diapers and urine HGA testing. Sequencing testing revealed that all members of this family had a novel samesense mutation c.15G>A at the edge of exon 1 of the HGD. By flow cytometry, the expression of HGD protein in the pediatric patients' peripheral blood mononuclear cells was barely expressed. NetGene2-2.42 and BDGP software showed that the mutation reduced the score of the 5' splice donor site and disrupted its normal splicing, and the RT-PCR product also demonstrated that the defect in the HGD protein was due to the lack of the first exon containing the start codon ATG after the mutation.

CONCLUSIONS

The novel mutation c.15G > A in HGD is associated with the AKU phenotype. It may affect the splicing of exon 1, leading to exon skipping, which impairs the structure and function of the protein.

Black Aortic Valve: Incidental Finding of Alkaptonuria

Background  Alkaptonuria is a rare autosomal recessive genetic disorder of tyrosine metabolism, which results in accumulation of homogentisic acid in various tissues, including the cardiovascular system. Case Description  We report on a 64-year-old man with mixed aortic valve disease who underwent conventional aortic valve replacement. Intraoperative aortotomy revealed black pigmentation of the intima of the ascending aorta and the aortic valve was observed with thickened and calcified dark black leaflets. Histopathological diagnosis of ochronosis of the aortic valve was made. Conclusion  Despite several previous signs and symptoms, the diagnosis of alkaptonuria was not established until aortic valve replacement.

A black heart: Aortic valve ochronosis secondary to alkaptonuria causing aortic stenosis

Alkaptonuria is a rare autosomal recessive genetic disorder where an accumulation of homogentisic acid in the tissues leads to ochronosis-a pathological dark pigmentation. It can affect various tissues and the weight bearing joints of the body, leading to degenerative arthropathy. On the rare occasion, it causes cardiac manifestations. We describe a case of aortic valve stenosis due to ochronosis secondary to alkaptonuria requiring aortic valve replacement.

Minimally invasive endoscopic aortic valve replacement for alkaptonuria-associated severe aortic stenosis: a case report and literature review

Alkaptonuria is an inherited metabolic disease caused by a genetic deficiency of homogentisate 1,2-dioxygenase and characterized by dark-brown connective tissue related to the deposition of oxidized homogentisic acid. Pigment deposition is also observed in the cardiovascular system, such as in the coronary arteries, cardiac valves, and aorta. Because aortic stenosis may develop secondary to pigment deposition-related calcification at the aortic valve, aortic valve replacement may be necessary for severe aortic valve disease. We report the case of a 75 year-old man with alkaptonuria-associated severe aortic stenosis who was successfully treated with minimally invasive endoscopic aortic valve replacement via right anterior minithoracotomy. The tricuspid aortic valve was severely calcified and both the valve and the aortic intima were ochronotic. No perioperative complications were observed and the postoperative course was uneventful.

Cardiovascular ochronosis

In this review, we summarize previously reported case reports (n=66) in which the presence of ochronotic pigment was found in one or more cardiovascular structures either at necropsy or after operative excision of a cardiac valve or portions of arteries or both. As illustration, we describe black pigment in operatively excised aortic valves and aorta in 2 patients, both probably examples of secondary ochronosis. Ochronosis appears to have fascinated a number of prominent historical figures in medicine, and this review also summarizes their important contributions to this topic.