variation seen in ventricular morphology It is not clear why isomerism of the right appendages should more frequently be associated with a univentricular atrioventricular connection or with either pulmonary atresia or stenosis Genetics The precise genetics of isomerism are still being delineated What is interesting to note is that studies in mice demonstrate that knockout of the same gene will lead to a similar result in atrial appendage morphology, whereas splenic morphology can vary This further implies that describing this clinical entity as isomerism segregated by atrial appendage morphology is more appropriate and helpful than describing this clinical entity as heterotaxy segregated by splenic morphology Several genes have been implicated in being associated with isomerism At least 20% to 30% of patients will have a mutation in one of these genes Isomerism has been described to have X-linked inheritance, autosomal dominant inheritance with reduced penetrance, and autosomal recessive inheritance.129 To date, more than 100 genes have been implicated in mice with isomerism, although only a proportion of these are also implicated in humans Studies in humans have been limited to smaller studies that are often case reports Therefore more data are needed over time to make conclusions regarding the genetic mechanisms of isomerism in humans.130 Genes that have been repeatedly noted to be affected in humans with isomerism include Nodal, Shh, ZIC3, PITX2, Lefty A, and Lefty B Genes in the ACVR, CCDC, CFC, DNAAF, DNAH, DANI, FOXH1, and NKX families have also been implicated.131–143 Recent data have demonstrated that certain genes being affected may lead to similar phenotypes in patients Some genes are more likely to be affected in those with right isomerism, whereas others are more likely to be affected in those with left isomerism The clinical course also appears to differ with different affected genes, likely due to underlying severity of disease.144 Clinical Considerations Through education and advocacy, clinicians are able properly to prepare patients and families of the nuances commonly associated with isomerism As mentioned previously, both left and right isomerism involve varying types of cardiac defects that will require surgical intervention during the early stages of life Depending on the severity, children may have multiorgan system involvement with potential to be critically ill Children may require prolonged hospitalizations, specifically in an intensive care unit, which can involve a variety of specialties such as gastroenterology, pulmonology, and cardiology Along with the initial diagnosis of isomerism, the inpatient and outpatient experiences patients and families will endure are likely to create feelings of stress, fear, anxiety, and helplessness Clinical considerations for this patient population should focus primarily on family education, patient outcomes, and patient advocacy Children with isomerism who undergo multiple surgical interventions and extended hospitalizations are at an increased risk for long-term complications such as pulmonary hypertension, arrhythmias, neurodevelopmental delays, and most importantly bacteremia Family education is the utmost important consideration because it promotes early identification, immediate management, and best patient outcomes Families should be counseled on what may occur during the inpatient hospitalization as well on what may occur in the outpatient setting Symptoms that should prompt medical evaluation as an outpatient must specifically be reviewed with patients and their families For example, to reduce the incidence of bacteremia, parents and families should understand the importance of good handwashing techniques, diligent oral hygiene, including daily care and regular dental visits, and the need to avoid ill persons It is crucial for parents to adhere to the administration of daily antibiotic prophylaxis and vaccinations A medical management plan should be developed and followed diligently among family members and school personnel if applicable Schoolaged children should wear a medical bracelet at all times The clinician should highlight that these infection risks are lifelong and continue into adulthood If complications occur and hospitalization is required, it is not uncommon for families to experience both physical and emotional difficulties Clinicians must be skilled in assessing the family's understanding of the status, treatment plan, and prognosis for the child They should assist with coordination of care and facilitate establishment of reasonable goals and expectations for both the family ... in an intensive care unit, which can involve a variety of specialties such as gastroenterology, pulmonology, and cardiology Along with the initial diagnosis of isomerism, the inpatient and outpatient experiences patients and families will