Hypoplastic left heart syndrome (HLHS) is a severe congenital cardiovascular malformation characterized by hypoplasia of the left ventricle, aorta, and other structures on the left side of the heart. The pathologic definition includes atresia or stenosis of both the aortic and mitral valves. Despite considerable progress in clinical and surgical management of HLHS, mortality and morbidity remain concerns. One barrier to progress in HLHS management is poor understanding of its cause. Several lines of evidence point to genetic origins of HLHS. First, some HLHS cases have been associated with cytogenetic abnormalities (e.g., Turner syndrome). Second, studies of family clustering of HLHS and related cardiovascular malformations have determined HLHS is heritable. Third, genomic regions that encode genes influencing the inheritance of HLHS have been identified. Taken together, these diverse studies provide strong evidence for genetic origins of HLHS and related cardiac phenotypes. However, using simple Mendelian inheritance models, identification of single genetic variants that \"cause\" HLHS has remained elusive, and in most cases, the genetic cause remains unknown. These results suggest that HLHS inheritance is complex rather than simple. The implication of this conclusion is that researchers must move beyond the expectation that a single disease-causing variant can be found. Utilization of complex models to analyze high-throughput genetic data requires careful consideration of study design.

Integrated human genetics and molecular/developmental biology studies have revealed that truncus arteriosus is highly associated with 22q11.2 deletion syndrome. Other congenital malformation syndromes and variants in genes encoding TBX, GATA, and NKX transcription factors and some signaling proteins have also been reported as its etiology.

Tetralogy of Fallot (TOF) and double-outlet right ventricle (DORV) are conotruncal defects resulting from disturbances of the second heart field and the neural crest, which can occur as isolated malformations or as part of multiorgan syndromes. Their etiology is multifactorial and characterized by overlapping genetic causes. In this chapter, we present the different genetic alterations underlying the two diseases, which range from chromosomal abnormalities like aneuploidies and structural mutations to rare single nucleotide variations affecting distinct genes. For example, mutations in the cardiac transcription factors NKX2-5, GATA4, and HAND2 have been identified in isolated TOF cases, while mutations of TBX5 and 22q11 deletion, leading to haploinsufficiency of TBX1, cause Holt-Oram and DiGeorge syndrome, respectively. Moreover, genes involved in signaling pathways, laterality determination, and epigenetic mechanisms have also been found mutated in TOF and/or DORV patients. Finally, genome-wide association studies identified common single nucleotide polymorphisms associated with the risk for TOF.

Ventricular septal defects (VSDs) are recognized as one of the commonest congenital heart diseases (CHD), accounting for up to 40% of all cardiac malformations, and occur as isolated CHDs as well as together with other cardiac and extracardiac congenital malformations in individual patients and families. The genetic etiology of VSD is complex and extraordinarily heterogeneous. Chromosomal abnormalities such as aneuploidy and structural variations as well as rare point mutations in various genes have been reported to be associated with this cardiac defect. This includes both well-defined syndromes with known genetic cause (e.g., DiGeorge syndrome and Holt-Oram syndrome) and so far undefined syndromic forms characterized by unspecific symptoms. Mutations in genes encoding cardiac transcription factors (e.g., NKX2-5 and GATA4) and signaling molecules (e.g., CFC1) have been most frequently found in VSD cases. Moreover, new high-resolution methods such as comparative genomic hybridization enabled the discovery of a high number of different copy number variations, leading to gain or loss of chromosomal regions often containing multiple genes, in patients with VSD. In this chapter, we will describe the broad genetic heterogeneity observed in VSD patients considering recent advances in this field.

Although atrial septal defects (ASD) can be subdivided based on their anatomical location, an essential aspect of human genetics and genetic counseling is distinguishing between isolated and familiar cases without extracardiac features and syndromic cases with the co-occurrence of extracardiac abnormalities, such as developmental delay. Isolated or familial cases tend to show genetic alterations in genes related to important cardiac transcription factors and genes encoding for sarcomeric proteins. By contrast, the spectrum of genes with genetic alterations observed in syndromic cases is diverse. Currently, it points to different pathways and gene networks relevant to the dysregulation of cardiomyogenesis and ASD pathogenesis. Therefore, this chapter reflects the current knowledge and highlights stable associations observed in human genetics studies. It gives an overview of the different types of genetic alterations in these subtypes, including common associations based on genome-wide association studies (GWAS), and it highlights the most frequently observed syndromes associated with ASD pathogenesis.

This chapter discusses the role of cardiac neural crest cells in the formation of the septum that divides the cardiac arterial pole into separate systemic and pulmonary arteries. Further, cardiac neural crest cells directly support the normal development and patterning of derivatives of the caudal pharyngeal arches, including the great arteries, thymus, thyroid, and parathyroids. Recently, cardiac neural crest cells have also been shown to indirectly influence the development of the secondary heart field, another derivative of the caudal pharynx, by modulating signaling in the pharynx. The contribution and function of the cardiac neural crest cells has been learned in avian models; most of the genes associated with cardiac neural crest function have been identified using mouse models. Together these studies show that the neural crest cells may not only critical for normal cardiovascular development but also may be involved secondarily because they represent a major component in the complex tissue interactions in the caudal pharynx and outflow tract. Cardiac neural crest cells span from the caudal pharynx into the outflow tract, and therefore may be susceptible to any perturbation in or by other cells in these regions. Thus, understanding congenital cardiac outflow malformations in human sequences of malformations resulting from genetic and/or environmental insults necessarily requires better understanding the role of cardiac neural crest cells in cardiac development.

Choanal atresia is an uncommon condition with an incidence of 1:5,000-8,000 live births, affecting females more frequently and often associated with other malformations. This case report presents a 42-year-old female patient who was born with bilateral choanal atresia and intervened surgically for the first time at birth. However, the formed orifice was reobstructed a few months afterward, necessitating reoperation in adulthood. The purpose of this case report is to describe bilateral choanal atresia in detail, including its clinical presentation, epidemiology, diagnosis, pathogenesis, and therapeutic approach. It aims to enhance understanding of this rare but significant condition.

BACKGROUND: The present study aimed to test the hypothesis stating that the cognitive potential of individuals with deafblindness is equal to those without a deafblind condition, an assumption that until now has been empirically unsubstantiated within the field of deafblindness.
METHODS: To explore the assumption, 15 children and adolescents with CHARGE underwent cognitive assessment with WISC-V using a sequential two-level assessment design. The 1st level involved standardized test conditions. The 2nd level was designed as a continuation of the performances obtained from the 1st level and involved accommodations to compensate for sensory motor impairment. Statistical procedures involved the sample as a whole and when divided into two subgroups: (i) participants with CHARGE without deafblindness; (ii) participants with CHARGE and deafblindness using the 1st level scores as base line.
RESULTS: Although results showed significantly lower scores in the deafblind subgroup with standardized procedures, they approximated the others after accommodating for their sensory deficits. This positive increase proved significant.
CONCLUSIONS: Findings supported the assumption of equal cognitive potential of individuals with and without deafblindness. Results indicated that the children and adolescents with deafblindness had most effect of the accommodations, enabling them to approximate the results of the subgroup without deafblindness. These gains were attributed enhanced accessibility endorsed by the accommodations and represented the participants latent cognitive dispositions only realized under certain circumstances.

CHARGE syndrome, characterized by a distinct set of clinical features, has been linked primarily to mutations in the CHD7 gene. Initially defined by specific clinical criteria, including coloboma, heart defects, choanal atresia, delayed growth, and ear anomalies, CHARGE syndrome\'s diagnostic spectrum has broadened since the identification of CHD7. Variants in this gene exhibit considerable phenotypic variability, leading to the adoption of the term \"CHD7 disorder\" to encompass a wider range of associated symptoms. Recent research has identified CHD7 variants in individuals with isolated features such as autism spectrum disorder or gonadotropin-releasing hormone deficiency. In this study, we present three cases from two different families exhibiting audiovestibular impairment as the primary manifestation of a CHD7 variant. We discuss the expanding phenotypic variability observed in CHD7-related disorders, highlighting the importance of considering CHD7 in nonsyndromic hearing loss cases, especially when accompanied by inner ear malformations on MRI. Additionally, we underscore the necessity of genetic counseling and comprehensive clinical evaluation for individuals with CHD7 variants to ensure appropriate management of associated health concerns.

OBJECTIVE: To examine the clinical characteristics and auditory performance of patients with CHARGE syndrome following cochlear implantation (CI), as well as the prognostic factors affecting auditory outcomes.
METHODS: Retrospective cohort.
METHODS: Tertiary academic center.
METHODS: A retrospective chart review was performed in patients with CHARGE syndrome who underwent CI from 2007 to 2022. The category of auditory performance (CAP) score was used to assess the CI outcomes, and factors that may affect the speech outcomes were also evaluated.
RESULTS: In 14 children with CHARGE syndrome, 22 CIs were performed, 6 unilaterally and 8 bilaterally. The mean age at CI was 25.9 months (range: 10-62). All patients had ear abnormalities and developmental delays, and cochlear nerve deficiency (CND) was present in all ears. At the last follow-up (mean: 49.6 months), the mean CAP score improved significantly compared to the preoperative measure (from 0.36 ± 0.81 to 3.21 ± 1.70, P = .001), with 6 patients (42.9%) achieving a CAP score of 4 points or higher. However, between the unilateral and bilateral CI groups, the final CAP score or change in CAP score was similar. Factors including age, coloboma, and CND did not significantly affect speech outcomes (all P > .05).
CONCLUSIONS: Even though CHARGE syndrome features challenging anomalies, CI can be conducted safely and can offer effective contribution to significant speech improvement. Patients with CHARGE syndrome should be given the opportunity to undergo CI to maximize their audiological progress.