LINE- and Alu-containing genomic instability hotspot at 16q24.1 associated with recurrent and nonrecurrent CNV deletions causative for ACDMPV.

Transposable elements modify human genome by inserting into new loci or by mediating homology-, microhomology-, or homeology-driven DNA recombination or repair, resulting in genomic structural variation. Alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV) is a rare lethal neonatal developmental lung disorder caused by point mutations or copy-number variant (CNV) deletions of FOXF1 or its distant tissue-specific enhancer. Eighty-five percent of 45 ACDMPV-causative CNV deletions, of which junctions have been sequenced, had at least one of their two breakpoints located in a retrotransposon, with more than half of them being Alu elements. We describe a novel ∼35 kb-large genomic instability hotspot at 16q24.1, involving two evolutionarily young LINE-1 (L1) elements, L1PA2 and L1PA3, flanking AluY, two AluSx, AluSx1, and AluJr elements. The occurrence of L1s at this location coincided with the branching out of the Homo-Pan-Gorilla clade, and was preceded by the insertion of AluSx, AluSx1, and AluJr. Our data show that, in addition to mediating recurrent CNVs, L1 and Alu retrotransposons can predispose the human genome to formation of variably sized CNVs, both of clinical and evolutionary relevance. Nonetheless, epigenetic or other genomic features of this locus might also contribute to its increased instability.

Pathogenetics of alveolar capillary dysplasia with misalignment of pulmonary veins.

Alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV) is a lethal lung developmental disorder caused by heterozygous point mutations or genomic deletion copy-number variants (CNVs) of FOXF1 or its upstream enhancer involving fetal lung-expressed long noncoding RNA genes LINC01081 and LINC01082. Using custom-designed array comparative genomic hybridization, Sanger sequencing, whole exome sequencing (WES), and bioinformatic analyses, we studied 22 new unrelated families (20 postnatal and two prenatal) with clinically diagnosed ACDMPV. We describe novel deletion CNVs at the FOXF1 locus in 13 unrelated ACDMPV patients. Together with the previously reported cases, all 31 genomic deletions in 16q24.1, pathogenic for ACDMPV, for which parental origin was determined, arose de novo with 30 of them occurring on the maternally inherited chromosome 16, strongly implicating genomic imprinting of the FOXF1 locus in human lungs. Surprisingly, we have also identified four ACDMPV families with the pathogenic variants in the FOXF1 locus that arose on paternal chromosome 16. Interestingly, a combination of the severe cardiac defects, including hypoplastic left heart, and single umbilical artery were observed only in children with deletion CNVs involving FOXF1 and its upstream enhancer. Our data demonstrate that genomic imprinting at 16q24.1 plays an important role in variable ACDMPV manifestation likely through long-range regulation of FOXF1 expression, and may be also responsible for key phenotypic features of maternal uniparental disomy 16. Moreover, in one family, WES revealed a de novo missense variant in ESRP1, potentially implicating FGF signaling in the etiology of ACDMPV.

Necrotizing Fasciitis of the Right Lower Extremity from Ruptured Appendicitis: Case Report.

CASE: The patient is a 16-year-old girl with history of dermatomyositis in remission for several years who presented with complaints of right thigh pain and elevated inflammatory markers. She presented to the Emergency Room (ER) on separate occasions and was diagnosed with right lower extremity necrotizing fasciitis secondary to ruptured appendix. She underwent 11 surgical procedures and extended hospital stay. CONCLUSION: This case is a unique presentation of ruptured appendicitis without abdominal pain that presented as right lower extremity necrotizing fasciitis and posed a diagnostic challenge. This case illustrates the importance of diligent evaluation and aggressive surgical management in musculoskeletal infections.

Coexistent Chorangioma and Hepatic Adenoma in One Twin Placenta: A Case Report and Review of the Literature.

Primary nontrophoblastic tumors of a placenta are very uncommon, with the majority being of vascular origin, such as chorangiomas and chorangiomatosis. Rare examples of tumor-like collections of liver tissue, morphologically consistent with hepatocellular adenomas, have been reported. We report the co-occurrence of a chorangioma and hepatic adenoma as a grossly single lesion on the fetal surface of a diamniotic dichorionic twin placenta.

Anemia and hepatosplenomegaly as presenting features in a child with rickets and secondary myelofibrosis.

Anemia and hepatosplenomegaly are common reasons for referring a child to a pediatric hematologist or oncologist. Among the many causes for these findings is severe rickets, which has been shown to be associated with secondary myelofibrosis and myeloid metaplasia. The authors present the case of an infant with severe rickets and secondary myelofibrosis and review the differential diagnosis of hepatosplenomegaly from the viewpoint of the pediatric hematologist/oncologist.