Holt-Oram syndrome is an autosomal dominant condition marked by heart and upper limb defects. Holt and Oram were the first to narrate this in 1960. Holt-Oram syndrome is the prototype of heart-hand syndromes and has recently been mapped to the long arm of chromosome 12 (12q2). This syndrome was described in 1960 by Dr Mary Holt and Dr Samuel Oram. It is an autosomal dominant condition resulting from a mutation in TBX5 located on chromosome 12q24.1, which regulates cardiac and limb morphogenesis. It must be differentiated from heart-hand syndrome type II (Tobatznik's syndrome) and heart-hand syndrome type III (MIM No. 140450), which are phenotypically similar. The latter do not map to 12q2, and atrial septal defects do not occur in these conditions. This syndrome is distinguished by heart problems as well as thumb aplasia or hypoplasia. It is sometimes referred to as atriodigital syndrome, upper limb-cardiovascular syndrome, heart-hand syndrome, cardiomelic syndrome, or cardiac limb syndrome. Other upper-limb anomalies include aplasia or hypoplasia of the radius, arm length variation, atypical forearm pronation and supination, uncommon thumb resistance, sloping shoulders, and restricted shoulder movement. All those who are affected have an aberrant carpal bone, which might be the only sign of the illness. Seventy-five percent of those with Holt-Oram syndrome have a congenital cardiac defect, which most frequently affects the septum. In this case, we report a girl who is 4 years and 6 months old and is a known case of Holt-Oram syndrome with an atrial septal defect. She underwent device closure and had come to the pediatric op with fever and cough. Holt-Oram syndrome also referred to as the heart-hand syndrome, is an autosomal dominant disorder that is characterized by upper limb abnormalities in association with congenital heart lesions. First described in 1960 by Holt and Oram, the syndrome was identified when thumb anomalies and atrial septal defects (ASD) were observed in family members across four generations. Since then, the identification of more cases and advances in technology has allowed for a greater understanding of the syndrome. However, there is still a significant proportion of individuals who are being born with the disorder in both industrialized and underdeveloped countries.

The literature on laminopathy with ventricular phenotype is extensive. However, the pathogenicity of LMNA variations in atrial lesions still lacks research. The purpose of this study was to characterize the atrial phenotypes and possible mechanisms in a large Chinese family with heart-hand syndrome carrying a LMNA missense variant in rod 2B domain (c.1003C>T p.R335W). Clinical characteristics were collected on the basis of the pedigree investigation. Comprehensive functional analyses, including molecular dynamic (MD) simulation, cellular, and animal functional assays, determined the pathogenicity in atrial myopathy. In the pedigree investigation, 6 of 13 of the mutation carriers showed heterogeneous cardiac phenotypes and 8 carriers also had brachydactyly. In silico molecular dynamics simulations predicted increased binding energy of the R335W mutant lamin A. Atrial cardiomyocytes (HL-1, human induced pluripotent stem cell-derived atrial cardiomyocytes) expressing R335W showed abnormal nuclear morphology, compromised DNA repair, and dysfunctional contraction. Adult zebrafish expressing mutant lamin A showed increased P wave duration in the electrocardiogram, decreased peak A wave velocity in echocardiography, and atrial lesions under the transmission electron microscope. LMNA p.R335W mutation leads to familial heart-hand syndrome characterized by an overlapping phenotype of prominent atrial lesions and brachydactyly. The unstable lamin dimerization and impaired DNA repair are possible mechanisms underlying cardiac phenotypes. Our findings consolidated the genetic role in the course of atrial arrhythmias and cardiac aging, which is helpful in the diagnosis and treatment of cardiac laminopathy.

Purpose: This study aims to identify genetic lesions in patients with congenital heart disease (CHD) with or without other phenotypes. In this study, over 400 patients were recruited and several novel variants in known causative genes were identified. A Chinese patient clinically diagnosed with HHS (patent ductus arteriosus, persistent left superior vena cava, and congenital absence of left arm radius) was included in the study cohort. Methods: Targeted, whole exome, and Sanger sequencing were performed to identify genetic lesions. The effects of the variant on ACTL6A RNA and protein were assessed using bioinformatics analysis. Results: At the start of the study, no mutations in known and candidate causative genes associated with CHD were identified. Seven years later, we noticed craniofacial deformities and identified a de novo heterozygous deletion variant in ACTL6A (NM_004301, c.478_478delT; p.F160Lfs*9). Intellectual disability and short stature were identified by a follow-up visit 10 years later. This variant leads to frameshift sequences and a premature termination codon and may affect the features of proteins. According to the nonsense-mediated mRNA decay theory, this variant may induce the decay of ACTL6A mRNA in patients. Conclusion: Our study reported the first ACTL6A variant in a Chinese individual, providing further evidence that ACTL6A is involved in heart and upper limb skeletal and intellectual development, thereby expanding the spectrum of ACTL6A variants. Thus, mutation analysis of the ACTL6A gene should be considered in patients with BAF-opathies or heart-hand syndromes due to potential misdiagnosis. Craniofacial dysmorphisms and intellectual disability are key to distinguishing these two diseases clinically, and attention to developmental delay/intellectual disability and craniofacial deformities will contribute to the diagnosis of BAF-opathies.

Holt-Oram syndrome (HOS) is a rare, autosomal dominant heart-hand syndrome caused by mutations in the TBX5 gene. A wide spectrum of TBX5 mutations have been reported previously, most resulting in a null allele leading to haploinsufficiency. TBX5 gene duplications have been previously reported in association with typical and atypical HOS phenotypes. Ulnar-Mammary syndrome (UMS) is a distinct rare, autosomal dominant condition caused by mutations in the TBX3 gene. TBX5 and TBX3 are physically linked in cis on human chromosome 12 and contiguous chromosome 12q24 deletions comprising both TBX5 and TBX3 genes have been previously reported but to our knowledge, duplications have never been described. We report on a large German family with at least 17 affected individuals over 6 generations bearing a duplication at 12q24.21 identified on array-CGH comprising both TBX5 and TBX3 genes. Affected patients are presenting with HOS and UMS symptoms, consisting of variable limb anomalies involving the radial and the ulnar rays and cardiac findings such as congenital heart defects, persistent arterial duct or aortic stenosis, and non-classical symptoms, such as supernumerary nipples and cardiomyopathy. Fluorescence in situ hybridisation confirmed a tandem duplication at the 12q24.21 locus. This is the first report of a contiguous TBX3/TBX5 duplication associated with HOS/UMS phenotype.