Derek A. Wong

Over the last few years, advances in next-generation sequencing technologies have decreased the cost of sequencing per base pair about 10-fold, improved accuracy, and greatly increased the speed of generating sequence data. Exome sequencing, which sequences the protein-coding region of the genome, has been rapidly applied to variant discovery in research settings and recent increases in accuracy have enabled development of clinical exome sequencing (CES) for mutation identification in patients with suspected genetic diseases.

Cutaneous granulomas with prominent caseating necrosis are a rare manifestation of immunodeficiency. Extensive and recalcitrant cutaneous viral infections can also be seen. We present a case of an 18-year-old white man with an early onset poorly characterized combined immunodeficiency syndrome who, over the past 5 years, developed enlarging tender red-purple plaques on his extremities and pink near-confluent macules on his chest and back. Previous biopsies of the red-purple plaques showed features of granuloma annulare. Histopathological examination of old and new biopsies revealed both sarcoidal and palisading necrobiotic granulomas with perforating features and elastophagocytosis. Stains and tissue cultures were negative for bacterial and fungal organisms. In addition, biopsy of a macule on the back demonstrated verruca plana with characteristics of epidermodysplasia verruciformis. As an infant, the patient had failure to thrive and a combined immunodeficiency, but was lost to follow-up for 15 years. He currently continues to have severe hypogammaglobinemia and cellular immunodeficiency. Intravenous immunoglobulin and prednisone were initiated and his plaques improved rapidly. Topical imiquimod was ineffective for the verruca plana. The patient and his parents are currently undergoing whole exome sequencing including evaluation for epidermodysplasia verruciformis 1 and 2 gene mutations. This case highlights the importance of including genetic immunodeficiency disorders in the clinical and histopathological differential diagnosis for cutaneous sarcoidal or palisading necrobiotic granulomas and for extensive cutaneous viral infection.

Deletions of the long arm of chromosome 18 have been previously reported in many patients. Most cases involve the more distal regions of the long arm (18q21.1‐>qter). However, proximal interstitial deletions involving 18q11.2 are extremely rare. Here we report on a 14‐month‐old female with a 4.7 Mb (19,667,062–24,401,876 hg19) de novo interstitial deletion within chromosomal band 18q11.2, which includes GATA6 and 24 other RefSeq genes. The clinical features of our patient include complex congenital heart defects, a double outlet right ventricle, a subaortic ventricular septal defect, D‐malposed great arteries, an atrial septal defect, a dysplastic aortic valve and patent ductus arteriosus. In addition, she had renal anomalies—a duplicated collecting system on the left and mild right hydronephrosis. These heart and renal defects are not reported in other patients with 18q proximal interstitial deletions. Heterozygous point mutations in GATA6, encoding for a zinc finger transcription factor, have been shown to cause congenital heart defects. Given the well‐established biological role of GATA6 in cardiac development, a deletion of GATA6 is very likely responsible for our patient's complex congenital heart defects. This is the smallest and most proximal 18q11.2 deletion involving GATA6 that is associated with complex congenital heart disease and renal anomalies.