A novel cardiovascular presentation of Alport Syndrome: spontaneous coronary artery dissection

Ascending aortic aneurysm and histopathology in Alport syndrome: a case report

BACKGROUND

Alport syndrome (AS) is caused by mutations in type IV collagen genes that typically target and compromise the integrity of basement membranes in kidney, ocular, and sensorineural cochlear tissues. Type IV and V collagens are also integral components of arterial walls, and whereas collagenopathies including AS are implicated in aortic disease, the incidence of aortic aneurysm in AS is unknown probably because of underreporting. Consequently, AS is not presently considered an independent risk factor for aortic aneurysm and more detailed case studies including histological evidence of basement membrane abnormalities are needed to determine such a possible linkage.

CASE PRESENTATION

Here, we present unique histopathological findings of an ascending aortic aneurysm collected at the time of surgery from an AS patient wherein hypertension was the only other known risk factor.

CONCLUSIONS

The studies reveal classical histological features of aortic aneurysm, including atheroma, lymphocytic infiltration, elastin disruption, and myxoid degeneration with probable AS association.

Vertebral and Basilar Artery Dissection in a Patient With Alport Syndrome

Basilar artery occlusion (BAO) is a rare cause of stroke associated with significant morbidity and mortality. It is most frequently thromboembolic in nature, but may be caused by vertebral artery dissection. We present a case of BAO in a 36-year-old woman with Alport syndrome. She was treated with emergent thrombectomy via the right vertebral artery with return to baseline neurological status. Her clinical status deteriorated later the same day and she was found to have re-occlusion. Repeat thrombectomy was complicated by persistent re-occlusion requiring 7 passes to achieve reperfusion. Unfortunately, her neurological exam remained poor and she was transitioned to comfort care, expiring on admission day 3. An autopsy demonstrated acute dissection of the left vertebral artery, basilar artery, and bilateral posterior cerebral arteries. Alport syndrome is a type IV collagenopathy most known for causing kidney disease. It may also be associated with vascular fragility as type IV collagen forms a significant component of the vascular basement membrane. There are reports of aortic, coronary, and cervical dissections, but few reports of intracranial dissections in patients with Alport syndrome. While iatrogenic dissection cannot be ruled out, the histological findings in this case are most consistent with spontaneous arterial dissection as the cause of her initial neurologic presentation. This highlights the need for further investigation into the relationship between Alport syndrome and vascular fragility and should alert clinicians to the possibility of intracranial dissection in patients with AS.

Exploring the Genetic Architecture of Spontaneous Coronary Artery Dissection Using Whole-Genome Sequencing

Background:

Spontaneous coronary artery dissection (SCAD) is a cause of acute coronary syndrome that predominantly affects women. Its pathophysiology remains unclear but connective tissue disorders (CTD) and other vasculopathies have been observed in many SCAD patients. A genetic component for SCAD is increasingly appreciated, although few genes have been robustly implicated. We sought to clarify the genetic cause of SCAD using targeted and genome-wide methods in a cohort of sporadic cases to identify both common and rare disease-associated variants.

Methods:

A cohort of 91 unrelated sporadic SCAD cases was investigated for rare, deleterious variants in genes associated with either SCAD or CTD, while new candidate genes were sought using rare variant collapsing analysis and identification of novel loss-of-function variants in genes intolerant to such variation. Finally, 2 SCAD polygenic risk scores were applied to assess the contribution of common variants.

Results:

We identified 10 cases with at least one rare, likely disease-causing variant in CTD-associated genes, although only one had a CTD phenotype. No genes were significantly associated with SCAD from genome-wide collapsing analysis, however, enrichment for TGF (transforming growth factor)-β signaling pathway genes was found with analysis of 24 genes harboring novel loss-of-function variants. Both polygenic risk scores demonstrated that sporadic SCAD cases have a significantly elevated genetic SCAD risk compared with controls.

Conclusions:

SCAD shares some genetic overlap with CTD, even in the absence of any major CTD phenotype. Consistent with a complex genetic architecture, SCAD patients also have a higher burden of common variants than controls.

Fibrillar Collagen Variants in Spontaneous Coronary Artery Dissection

IMPORTANCE

Spontaneous coronary artery dissection (SCAD) is an increasingly recognized nonatherosclerotic cause of acute myocardial infarction enriched among individuals with early-onset myocardial infarction but is of unclear etiology.

OBJECTIVE

To assess which genes contribute to the development of SCAD.

DESIGN, SETTING, AND PARTICIPANTS

To prioritize genes influencing risk for SCAD, whole-exome sequencing was performed among individuals with SCAD in the discovery and replication cohorts from a tertiary care hospital outpatient specialty clinic, and gene set enrichment analyses were also performed for disruptive coding variants. All patients were sequentially enrolled beginning July 2013. Aggregate prevalence of rare disruptive variants for prioritized gene sets was compared between individuals with SCAD with population-based controls comprising 46 468 UK Biobank participants with whole-exome sequencing. Complementary mice models were used for in vivo validation. Analysis took place between June 2020 and January 2021.

MAIN OUTCOMES AND MEASURES

The frequency and identity of rare genetic variants in individuals with SCAD.

RESULTS

Of 130 patients, 109 (83.8%) were female (26 of 32 [81.2%] in the discovery cohort and 83 of 98 [84.7%] in the replication cohort) with mean (SD) age at first SCAD event of 48.41 (8.76) years in the discovery cohort and 47.74 (10.09) years in the replication cohort. Across all patients with SCAD, rare disruptive variants were found within 10 collagen genes (COL3A1, COL5A1, COL4A1, COL6A1, COL5A2, COL12A1, COL4A5, COL1A1, COL1A2, and COL27A1) were 17-fold (P = 1.5 × 10-9) enriched among individuals with SCAD compared with a background of 2506 constrained genes expressed in coronary artery. Furthermore, compared with individuals from the UK Biobank, individuals with SCAD were 1.75-fold (P = .04) more likely to carry disruptive rare variants within fibrillar collagen genes. Complementary mice models haploinsufficient for Col3a1 or Col5a1, the 2 most common collagen gene variants identified in SCAD cases, demonstrated increased risk of arterial dissection and increased size of arterial diameters especially in female mice, with resulting changes in collagen fibril organization and diameter.

CONCLUSIONS AND RELEVANCE

Unbiased gene discovery in patients with SCAD with independent human and murine validation highlights the role of the extracellular matrix dysfunction in SCAD.

Corneal endothelial cell abnormalities in X-linked Alport syndrome

Background: X-linked Alport syndrome results from the effect of COL4A5 mutations on basement membranes in the kidney, ear and eye. This study investigated individuals with X-linked Alport syndrome for corneal abnormalities.Patients and Methods: Six men and four women from 8 families with genetically-diagnosed X-linked Alport syndrome underwent ophthalmological examination including slit lamp examination and corneal endothelial specular microscopy. Results for corneal microscopy for men and women with X-linked disease were compared separately with the mean values for age- matched normals using the student's t test.Results: Five of the 6 men had end-stage kidney failure, all 6 had a hearing loss, three had lenticonus, and three had a central fleck retinopathy. Two men had a history of recurrent corneal erosions but no evidence of posterior polymorphous corneal dystrophy. None of the four women had kidney failure, but two had a hearing loss, and two had a central fleck retinopathy. One woman, whose son had recurrent corneal erosions, also had erosions, but no features of a posterior polymorphous corneal dystrophy.Corneal specular microscopy demonstrated abnormalities in affected men and women, with larger endothelial cells (p = .0001 in men, p = .004 in women) fewer 6-sided cells (p = .0001, p = .001 respectively) and reduced cell density (p = .03, p = .02 respectively) than normal.Conclusions: Recurrent corneal erosions are common in men and women with X-linked Alport syndrome, but posterior polymorphous corneal dystrophy is rare. The abnormal corneal endothelial cells in affected men and women are consistent with an abnormal Descemet membrane, and the reduced cell density resembles the reduced podocyte numbers found in the Alport glomerulus.

Spontaneous Coronary Artery Dissection: A Rare Manifestation of Alport Syndrome

Alport syndrome (AS) is a genetic disorder due to inheritance of genetic mutations which lead to production of abnormal type IV collagen. AS has been associated with renal, auditory, and ocular diseases due to the presence of abnormal alpha chains of type IV collagen in the glomerulus, cochlea, cornea, lens, and retina. The resulting disorder includes hereditary nephritis, corneal opacities, anterior lenticonus, fleck retinopathy, temporal retinal thinning, and sensorineural deafness. Aortic and aortic valve pathologies have been described as extrarenal manifestations of AS in multiple case reports. One case report described intramural hematoma of the coronary artery. We report the first case of true spontaneous coronary artery dissection (SCAD) with an intimal flap as a very rare manifestation of AS. The patient is a 36-year-old female with history of AS with chronic kidney disease, hypertension, and obesity who presented to the emergency room with acute onset of substernal chest pain radiating to her neck and arms. Troponin was elevated, and ECG showed transient 1 mm ST-segment elevation in the inferior leads. Subsequent coronary angiography revealed localized dissection of the left circumflex artery. Percutaneous coronary angioplasty was performed and her symptoms improved. This case illustrates that SCAD may be a manifestation of AS patients with chest pain.