Two De Novo Mutations in an Autistic Child Who Had Previously Undergone Transplantation for Dilated Cardiomyopathy: The Importance of Keeping an Open Mind.

We report the finding of 2 de novo mutations in an 8-year-old boy with developmental delay and autism who underwent heart transplantation at 1 year of age for idiopathic dilated cardiomyopathy. We identified a de novo microdeletion at chromosome 2p16.3 involving the neurexin-1 (NRXN1) gene and a de novo pathologic variant (Pro838Leu) in the myosin heavy chain 7 (MYH7) gene. This case emphasizes the importance of comprehensive genetic evaluation in patients with cardiomyopathy, particularly if they have extracardiac abnormalities, and the necessity of interpreting variants with attention to the phenotype. A complete genetic diagnosis may require multiple testing modalities.

An Algorithm Measuring Donor Cell-Free DNA in Plasma of Cellular and Solid Organ Transplant Recipients That Does Not Require Donor or Recipient Genotyping.

Cell-free DNA (cfDNA) has significant potential in the diagnosis and monitoring of clinical conditions. However, accurately and easily distinguishing the relative proportion of DNA molecules in a mixture derived from two different sources (i.e., donor and recipient tissues after transplantation) is challenging. In human cellular transplantation, there is currently no useable method to detect in vivo engraftment, and blood-based non-invasive tests for allograft rejection in solid organ transplantation are either non-specific or absent. Elevated levels of donor cfDNA have been shown to correlate with solid organ rejection, but complex methodology limits implementation of this promising biomarker. We describe a cost-effective method to quantify donor cfDNA in recipient plasma using a panel of high-frequency single nucleotide polymorphisms, next-generation (semiconductor) sequencing, and a novel mixture model algorithm. In vitro, our method accurately and rapidly determined donor:recipient DNA admixture. For in vivo testing, donor cfDNA was serially quantified in an infant with a urea cycle disorder after receiving six daily infusions of donor liver cells. Donor cfDNA isolated from 1 to 2 ml of recipient plasma was detected as late as 24 weeks after infusion suggesting engraftment. The percentage of circulating donor cfDNA was also assessed in pediatric and adult heart transplant recipients undergoing routine endomyocardial biopsy with levels observed to be stable over time and generally measuring <1% in cases without moderate or severe cellular rejection. Unlike existing non-invasive methods used to define the proportion of donor cfDNA in solid organ transplant patients, our assay does not require sex mismatch, donor genotyping, or whole-genome sequencing and potentially has broad application to detect cellular engraftment or allograft injury after transplantation.