Sengers syndrome and AGK-related disorders - Minireview of phenotypic variability and clinical outcomes in molecularly confirmed cases

Sengers syndrome (OMIM# 212350) is a rare autosomal recessive mitochondrial disease caused by biallelic pathogenic variants in the AGK gene, which encodes the acylglycerol kinase enzyme. The syndrome was originally defined as a "triad" of hypertrophic cardiomyopathy, cataracts, and lactic acidosis, with or without skeletal myopathy. The clinical manifestation of Sengers Syndrome exhibits substantial heterogeneity, with mild and severe/infantile forms reported. Further, biallelic AGK pathogenic variants have also been identified in a familial case of non-syndromic isolated cataract (OMIM# 614691), expanding our understanding of the gene's influence beyond the originally defined syndrome. In this study, we provide a systematic review of molecularly confirmed cases with biallelic AGK pathogenic variants (Supplementary Table 1). Our analysis demonstrates the variable expressivity and penetrance of the central features of Sengers syndrome, as follows: cataracts (98%), cardiomyopathy (88%), lactic acidosis (adjusted 88%), and skeletal myopathy (adjusted 74%) (Table 1). Furthermore, we investigate the associations between genotype, biochemical profiles, and clinical outcomes, with a particular focus on infantile mortality. Our findings reveal that patients carrying homozygous nonsense variants have a higher incidence of infant mortality and a lower median age of death (p = 0.005 and p = 0.02, Table 2a). However, the location of pathogenic variants within the AGK domains was not significantly associated with infantile death (p = 0.62, Table 2b). Additionally, we observe a borderline association between the absence of lactic acidosis and longer survival (p = 0.053, Table 2c). Overall, our systematic review sheds light on the diverse clinical manifestations of AGK-related disorders and highlights potential factors that influence its prognosis. These provide important implications for the diagnosis, treatment, and counseling of affected individuals and families.

Surgical management of pediatric renovascular hypertension and midaortic syndrome at a single-center multidisciplinary program

OBJECTIVE

To evaluate the outcomes of various surgical approaches in the treatment of renovascular hypertension and midaortic syndrome (MAS) in children.

METHODS

We performed a retrospective medical record review of patients who had undergone surgery for renovascular hypertension from 2010 to 2018 at our center under the care of a multidisciplinary team. The operative interventions included mesenteric artery growth improves circulation (MAGIC), tissue expander-stimulated lengthening of arteries (TESLA), aortic bypass using polytetrafluorethylene, renal artery reimplantation, and autotransplantation. The MAGIC procedure uses the meandering mesenteric artery as a free conduit for aortic bypass. The TESLA procedure is based on lengthening the normal distal aorta and iliac arteries by gradual filling of a retroaortic tissue expander for several weeks, followed by resection of the stenotic aorta and subsequent primary reconstruction.

RESULTS

A total of 39 patients were identified, 10 with isolated renal artery stenosis, 26 with MAS, and 3 with systemic inflammatory vasculitis. The median age at presentation and surgery was 6.4 years (range, 0-16.3 years) and 9.3 years (range, 0-9.2 years), respectively. The MAS-associated syndromes included neurofibromatosis type 1 (15.4%) and Williams syndrome (5.1%), although most cases were idiopathic. At surgery, 33.3% had had stage 1 hypertension (HTN), 53.8% stage 2 HTN, and 12.8% normal blood pressure with a median of three antihypertensive medications. Follow-up of 37 patients at a median of 2.5 years demonstrated normal blood pressure in 86.1%, stage 1 HTN in 8.3%, and stage 2 HTN in 5.6%, with a median of one antihypertensive medication for the entire cohort.

CONCLUSIONS

The patterns of vascular involvement leading to renovascular hypertension in children are variable and complex, requiring thoughtful multidisciplinary planning and surgical decision-making. The MAGIC and TESLA procedures provide feasible approaches for aortic bypass and reconstruction using autologous tissues and will result in normalization of blood pressure in 85% of children 2.5 years after surgery.

High-Sensitivity Dry Rehydratable Film Method for Enumeration of Coliforms in Dairy Products: Collaborative Study

A dry-film coliform count plate that is inoculated with 5 mL sample was compared with the Violet Red Bile Agar plate method in a collaborative study by 18 laboratories. Products analyzed were 2% milk, chocolate milk, cream, vanilla ice cream, cottage cheese, and cheese. Collaborators tested blind duplicate uninoculated samples and samples inoculated at low, medium, and high level. Significantly (P< 0.05) higher numbers of coliforms were recovered by the dry-film method from 2% milk samples at the 3 inoculum levels, the chocolate milk at the low- and high-inoculum levels, and the cream at the high-inoculum level. Significantly higher counts were obtained by the agar method for cottage cheese samples at the low-inoculum level. The repeatability standard deviation for the dry-film method was significantly higher for the high-inoculum level chocolate milk sample and the medium-inoculum level cottage cheese. The same statistic was significantly higher for the agar method at all 3 inoculum levels in the 2% milk and the medium-inoculum level cream. The high-sensitivity dry rehydratable film method for enumeration of coliforms in dairy products has been adopted first action by AOAC INTERNATIONAL.

Relative Effectiveness of Selenite Cystine Broth, Tetrathionate Broth, and Rappaport-Vassiliadis Medium for Recovery of Salmonella spp. from Raw Flesh, Highly Contaminated Foods, and Poultry Feed: Collaborative Study

A collaborative study was performed in 18 laboratories to validate use of Rappaport-Vassiliadis (RV) medium in the standard culture method for recovery of Salmonella spp. from raw, highly contaminated foods and poultry feed. RV medium made from its individual ingredients and incubated at 42�C was compared with selenite cystine (SC) broth incubated at 35�C and tetrathionate (TT) broth incubated at 35� and 43�C for effectiveness in recovery of Salmonella spp. Four artificially contaminated foods (oysters, frog legs, mushrooms, and shrimp) and poultry feed and one naturally contaminated food (chicken) were analyzed. The artificially contaminated foods were inoculated with single serovars of Salmonella at target levels of 0.04 colony-forming units (CFU)/g for the low level and 0.4 CFU/g for the high level. For analysis of 1125 test portions, RV medium (42�C) recovered Salmonellairom 409 test portions; TT (43�C), from 368 test portions; TT (35�C), from 310 test portions; and SC (35�C), from 334 test portions. Overall, RV medium was comparable with or better than other selective enrichments for recovery of Salmonella from the foods in this study, except mushrooms. From mushrooms, SC broth (35�C) recovered more positive test portions than did RV medium (42�C) and TT broth (43�C). The method for detection of Salmonella in raw, highly contaminated foods and

Cardiac Abnormalities in Patients With Hutchinson-Gilford Progeria Syndrome

Importance

Hutchinson-Gilford progeria syndrome (HGPS) is an ultrarare disorder associated with premature death due to cardiovascular events during the second decade of life. However, because of its rarity (107 identified living patients), the natural history of cardiac disease remains uncharacterized. Therefore, meaningful cardiac end points for clinical trials have been difficult to establish.

Objective

To examine the course of appearance of cardiac abnormalities in patients with HGPS to identify meaningful cardiac end points for use in future clinical trials.

Design, Setting, and Participants

In this prospective, cross-sectional, observational study, 27 consecutive patients with clinically and genetically confirmed classic HGPS were evaluated at a single center for 1 visit from July 1, 2014, through February 29, 2016, before initiation of treatment.

Exposure

Classic HGPS.

Main Outcomes and Measures

Echocardiography was used to assess ventricular and valve function using standard techniques. Diastolic left ventricular (LV) function was assessed using tissue Doppler imaging. Previously published normative data were used to adjust findings to age and body size.

Results

This study included 27 patients (median age, 5.6 years; age range, 2-17 years; 15 [56%] male). Among echocardiographic indicators, LV diastolic dysfunction, defined as a tissue Doppler septal or lateral early velocity z score less than -2, was the most prevalent abnormality, seen in 16 patients (59%). Diastolic dysfunction was seen in all age groups, and its prevalence increased with age, mirroring findings seen during normal aging. Indicators of LV diastolic function were more abnormal in older patients. The z scores for lateral and septal early velocities were lower (r = -0.77, P < .001; and r = -0.66, P < .001, respectively), whereas those for the ratio of early mitral inflow velocity to early diastolic tissue Doppler myocardial velocity were higher (r = 0.80, P < .001; and r = 0.72, P < .001, respectively) in older patients. Other echocardiographic findings, including LV hypertrophy, LV systolic dysfunction, and valve disease, were less prevalent in the first decade and were seen more frequently in the second decade.

Conclusions and Relevance

In this largest-to-date cohort of patients with HGPS, LV diastolic dysfunction was the most prevalent echocardiographic abnormality and its prevalence increased with aging. Echocardiographic indicators of LV diastolic function may be useful end points in future clinical trials in this patient population.

Integrin β3 inhibition is a therapeutic strategy for supravalvular aortic stenosis

Misra et al. elucidate the origin of smooth muscle cells involved in supravalvular aortic stenosis and identify the integrin β3 pathway as a therapeutic target in this disease.

The aorta is the largest artery in the body, yet processes underlying aortic pathology are poorly understood. The arterial media consists of circumferential layers of elastic lamellae and smooth muscle cells (SMCs), and many arterial diseases are characterized by defective lamellae and excess SMCs; however, a mechanism linking these pathological features is lacking. In this study, we use lineage and genetic analysis, pharmacological inhibition, explant cultures, and induced pluripotent stem cells (iPSCs) to investigate supravalvular aortic stenosis (SVAS) patients and/or elastin mutant mice that model SVAS. These experiments demonstrate that multiple preexisting SMCs give rise to excess aortic SMCs in elastin mutants, and these SMCs are hyperproliferative and dedifferentiated. In addition, SVAS iPSC-derived SMCs and the aortic media of elastin mutant mice and SVAS patients have enhanced integrin β3 levels, activation, and downstream signaling, resulting in SMC misalignment and hyperproliferation. Reduced β3 gene dosage in elastin-null mice mitigates pathological aortic muscularization, SMC misorientation, and lumen loss and extends survival, which is unprecedented. Finally, pharmacological β3 inhibition in elastin mutant mice and explants attenuates aortic hypermuscularization and stenosis. Thus, integrin β3–mediated signaling in SMCs links elastin deficiency and pathological stenosis, and inhibiting this pathway is an attractive therapeutic strategy for SVAS.

Outcomes After Primary Transcatheter Therapy in Infants and Young Children With Severe Bilateral Peripheral Pulmonary Artery Stenosis

Background—

Angioplasty and stent implantation have become accepted therapies for isolated peripheral pulmonary stenosis, and have been shown to increase vessel diameter and reduce right ventricular (RV) pressure acutely in patients with pulmonary artery (PA) stenosis. The purpose of this study was to assess long-term outcomes after primary transcatheter therapy for peripheral pulmonary stenosis.

Methods and Results—

We studied 69 patients who underwent primary transcatheter intervention for severe isolated peripheral pulmonary stenosis at ≤5 years of age. Genetic/syndromic diagnoses included Williams syndrome (n=23), non-Williams familial arteriopathy (n=12), and Alagille syndrome (n=3). At the initial PA intervention, median RV:aortic pressure ratio decreased from 1.00 to 0.88 (median decrease, 0.18; P <0.001). Patients with a higher preintervention RV:aortic pressure ratio had a greater reduction ( P <0.001). During follow-up (median, 8.5 years), 10 patients died, 5 from complications of PA catheterization (all before 1998). Thirteen patients underwent surgical PA intervention, most within 1 year and along with repair of supravalvar aortic stenosis. Freedom from any PA reintervention was 38±6% at 1 year and 22±6% at 5 years. The median RV:aortic pressure ratio decreased from 1.0 at baseline to 0.53 at the most recent catheterization ( P <0.001), and 82% of patients with available clinical follow-up were asymptomatic.

Conclusions—

Transcatheter therapy for infants with severe peripheral pulmonary stenosis has become safer, regardless of genetic condition. Coupled with reintervention and surgical relief in selected cases, RV:aortic pressure ratios decrease substantially and most patients are asymptomatic at late follow-up.

Patterns of care at end of life in children with advanced heart disease

OBJECTIVE

To describe patterns of care for pediatric patients with advanced heart disease who experience in-hospital death.

DESIGN

Retrospective single-institution medical record review.

SETTING

A tertiary care pediatric hospital.

PARTICIPANTS

All patients younger than 21 years who died in the inpatient setting between January 1, 2007, and December 31, 2009, with primary cardiac diagnoses or who had ever received a cardiology consult (N=468). After excluding patients with significant noncardiac primary diagnoses, 111 children formed the analytic sample.

MAIN OUTCOME MEASURE

In-hospital deaths of children with heart disease during a 3-year period.

RESULTS

Median age at death was 4.8 months (age range,1 day to 20.5 years), with 84 deaths (75.7%) occurring before age 1 year. Median length of terminal hospital stay was 22 days (range, 1-199 days). Diagnoses included 84 patients (75.7%) with congenital heart disease, 10 (9.0%)with cardiomyopathy/myocarditis, 9 (8.1%) with pulmonary hypertension, and 8 (7.2%) with heart transplants.Sixty-two patients (55.9%) had received cardio-pulmonary resuscitation during their last hospital admission. At the end of life, 21 children (18.9%) had gastrostomy tubes and 26 (23.4%) had peritoneal drains.Most patients (91.9%) received ventilation, with half also receiving mechanical circulatory support. Eighty-three patients (74.8%) experienced additional end-organ failure. Classified by mode of death, 76 patients (68.5%) had disease-directed support withdrawn, 28 (25.2%) died during resuscitation, and 7 (6.3%) died while receiving comfort care after birth. Eighty-three percent of parents were present at the time of death.

CONCLUSION

Infants and children who die of advanced heart disease frequently succumb in the intensive care setting with multisystem organ failure and exposure to highly technical care.

Cardiovascular pathology in Hutchinson-Gilford progeria: correlation with the vascular pathology of aging

OBJECTIVE

Children with Hutchinson-Gilford progeria syndrome (HGPS) exhibit dramatically accelerated cardiovascular disease (CVD), causing death from myocardial infarction or stroke between the ages of 7 and 20 years. We undertook the first histological comparative evaluation between genetically confirmed HGPS and the CVD of aging.

METHODS AND RESULTS

We present structural and immunohistological analysis of cardiovascular tissues from 2 children with HGPS who died of myocardial infarction. Both had features classically associated with the atherosclerosis of aging, as well as arteriolosclerosis of small vessels. In addition, vessels exhibited prominent adventitial fibrosis, a previously undescribed feature of HGPS. Importantly, although progerin was detected at higher rates in the HGPS coronary arteries, it was also present in non-HGPS individuals. Between the ages of 1 month and 97 years, progerin staining increased an average of 3.34% per year (P<0.0001) in coronary arteries.

CONCLUSIONS

We find concordance among many aspects of cardiovascular pathology in both HGPS and geriatric patients. HGPS generates a more prominent adventitial fibrosis than typical CVD. Vascular progerin generation in young non-HGPS individuals, which significantly increases throughout life, strongly suggests that progerin has a role in cardiovascular aging of the general population.

Male-to-male transmission of Costello syndrome: G12S HRAS germline mutation inherited from a father with somatic mosaicism

Costello syndrome is a rare congenital anomaly syndrome associated with mental retardation and predisposition to benign and malignant tumors, caused by heterozygous missense mutations in the HRAS oncogene. Previously, all molecularly analyzed mutations appeared de novo, and most arose in the paternal germline. A single patient with somatic mosaicism for a Costello syndrome causing HRAS mutation has been reported. Here we describe the first documented transmission of an HRAS mutation from a parent with somatic mosaicism to a child with typical Costello syndrome. Prior to the identification of the underlying gene mutation in Costello syndrome, this family had been identified clinically. The proband was subsequently found to carry a G12S HRAS germline mutation. Testing of the parents for parental origin identified his father as mosaic for the same HRAS mutation. The mother was found not to carry an HRAS mutation. The causative familial mutation is identified as a c.34G > A, which is the most common mutation in the HRAS gene in patients with Costello syndrome. The father carries the mutation in 7-8% of his alleles. This is the second case of mosaicism observed in Costello syndrome and the first direct molecular evidence of father-to-son transmission of the disease-causing mutation. Our observation underlines the importance of parental evaluation, and may have implications for genetic counseling and clinical practice.

The longitudinal course of cardiomyopathy in Friedreich's ataxia during childhood

BACKGROUND

Clinical heart disease was recognized in the first descriptions of Friedreich's ataxia (FA). Cardiac manifestations reported for this progressive neurologic disease include hypertrophic cardiomyopathy, dilated cardiomyopathy, and electrophysiologic disturbances. Longitudinal data for childhood cases are limited. This study aimed to define the longitudinal course of the cardiac abnormalities with FA diagnosed during childhood and to correlate the presence of cardiomyopathy with clinical and genetic factors.

METHODS

A retrospective chart review was conducted, with prospective, blinded interpretation of echocardiograms and electrocardiograms. All the patients with a diagnosis of FA referred to the cardiology department of a single institution from 1974 to 2004 were included in the study.

RESULTS

This study investigated a total of 113 echocardiograms for 28 patients. Overall, the group had left ventricular hypertrophy and normal systolic function, with a median mass z-score of 2.48 (range, -3.8 to 35.6) and a median ejection fraction (EF) of 61% (range, 23-81%). Of the 28 patients, 23 (82%) had two or more echocardiograms. The median follow-up time to the most recent echocardiogram was 5.1 years (range, 0.4-16.5 years). Many in this longitudinal follow-up cohort (57%) showed hypertrophic cardiomyopathy on at least one echocardiogram, with the last follow-up assessment showing systolic dysfunction for 38% of these patients. There was a slow nonlinear decline in systolic function over time, with the mean EF decreasing more rapidly as age increased (p = 0.02) and maintenance of EF in the normal range until the age of 22 years. Of the 12 patients with systolic dysfunction and follow-up echocardiograms, 10 showed improvement to the normal EF range on at least one echocardiogram, and 5 remained normal through the last study. None of the trends in cardiac function and morphology correlated with frataxin GAA repeat length (the primary genetic defect in FA) or ambulatory status. One patient required an implantable defibrillator. There were no deaths or heart transplantations.

CONCLUSIONS

Overall, patients with FA have preserved cardiac function with increased mass throughout childhood. Because many patients who experience depressed systolic function show improvement in subsequent studies, evaluation for potentially reversible causes of heart failure should be conducted. Relative clinical stability during childhood and maintenance of normal systolic function into the second decade may be helpful for parent and patient education.

Acquired immune cytopenias post-cardiac transplantation respond to rituximab

Hematologic abnormalities following solid organ transplantation are infrequently autoimmune in origin. We present a series of autoimmune cytopenias developing as a late complication of pediatric cardiac transplantation. Autoimmune cytopenias represented include autoimmune hemolytic anemia, acquired Glanzmann thrombasthenia, and idiopathic thrombocytopenic purpura. Standard therapies were used in each patient without sustainable results. Eventually, each patient was treated with and responded to rituximab. In this report, we review these cases, propose potential mechanisms for development of autoimmune cytopenias, and discuss our experience with rituximab in managing refractory autoimmune cytopenias.

Further delineation of cardiac abnormalities in Costello syndrome

We review the cardiac abnormalities in 94 patients (27 new, 67 literature) with Costello syndrome, an increasingly recognized syndrome consisting of increased birth weight, postnatal growth retardation, and distinctive facial, skin, and musculoskeletal features (MIM 218040). A cardiac abnormality was found in 59 (63%) patients, with each of three categories occurring in approximately one-third of patients. A cardiovascular malformation (CVM) was noted in 30%, typically pulmonic stenosis (46% of those with a CVM). Cardiac hypertrophy was reported in 34%, which involved the left ventricle in 50% and was usually consistent with classic hypertrophic cardiomyopathy (HCM). A variety of rhythm disturbances were reported in 33%. Most (74%) were atrial tachycardia that was reported as supraventricular, chaotic, multifocal, or ectopic. Of 31 patients with a rhythm abnormality, 22 (68%) had an additional abnormality, i.e., CVM (4), cardiac hypertrophy (12), or both (6). Nine patients had isolated dysrhythmia, five (56%) of whom died. All of the 12 (13%) patients who died had a cardiac abnormality. One patient died of embryonal rhabdomyosarcoma, but in the remainder, a cardiac cause of death could not be disproved. All patients with Costello syndrome need a baseline cardiology evaluation with echocardiography and Holter monitoring. Additional prospective evaluations, even in patients without apparent cardiac abnormalities, would be prudent, although data are insufficient to propose a specific schedule.

Mutations in sarcomere protein genes as a cause of dilated cardiomyopathy

BACKGROUND

The molecular basis of idiopathic dilated cardiomyopathy, a primary myocardial disorder that results in reduced contractile function, is largely unknown. Some cases of familial dilated cardiomyopathy are caused by mutations in cardiac cytoskeletal proteins; this finding implicates defects in contractile-force transmission as one mechanism underlying this disorder. To elucidate this important cause of heart failure, we investigated other genetic causes of dilated cardiomyopathy.

METHODS

Clinical evaluations were performed in 21 kindreds with familial dilated cardiomyopathy. A genome-wide linkage study prompted a search of the genes encoding beta-myosin heavy chain, troponin T, troponin I, and alpha-tropomyosin for disease-causing mutations.

RESULTS

A genetic locus for mutations associated with dilated cardiomyopathy was identified at chromosome 14q11.2-13 (maximal lod score, 5.11; theta=0), where the gene for cardiac beta-myosin heavy chain is encoded. Analyses of this and other genes for sarcomere proteins identified disease-causing dominant mutations in four kindreds. Cardiac beta-myosin heavy-chain missense mutations (Ser532Pro and Phe764Leu) and a deletion in cardiac troponin T (deltaLys210) caused early-onset ventricular dilatation (average age at diagnosis, 24 years) and diminished contractile function and frequently resulted in heart failure. Affected persons had neither antecedent cardiac hypertrophy (average maximal left-ventricular-wall thickness, 8.5 mm) nor histopathological findings characteristic of hypertrophy.

CONCLUSION

Mutations in sarcomere protein genes account for approximately 10 percent of cases of familial dilated cardiomyopathy and are particularly prevalent in families with early-onset ventricular dilatation and dysfunction. Because distinct mutations in sarcomere proteins cause either dilated or hypertrophic cardiomyopathy, the effects of mutant sarcomere proteins on muscle mechanics must trigger two different series of events that remodel the heart.

Elastin: mutational spectrum in supravalvular aortic stenosis

Supravalvular aortic stenosis (SVAS) is a congenital narrowing of the ascending aorta which can occur sporadically, as an autosomal dominant condition, or as one component of Williams syndrome. SVAS is caused by translocations, gross deletions and point mutations that disrupt the elastin gene (ELN) on 7q11.23. Functional hemizygosity for elastin is known to be the cause of SVAS in patients with gross chromosomal abnormalities involving ELN. However, the pathogenic mechanisms of point mutations are less clear. One hundred patients with diagnosed SVAS and normal karyotypes were screened for mutations in the elastin gene to further elucidate the molecular pathology of the disorder. Mutations associated with the vascular disease were detected in 35 patients, and included nonsense, frameshift, translation initiation and splice site mutations. The four missense mutations identified are the first of this type to be associated with SVAS. Here we describe the spectrum of mutations occurring in familial and sporadic SVAS and attempt to define the mutational mechanisms involved in SVAS. SVAS shows variable penetrance within families but the progressive nature of the disorder in some cases, makes identification of the molecular lesions important for future preventative treatments.