Genome-first approach for the characterization of a complex phenotype with combined NBAS and CUL4B deficiency.

Biallelic variants in neuroblastoma-amplified sequence (NBAS) cause an extremely broad spectrum of phenotypes. Clinical features range from isolated recurrent episodes of liver failure to multisystemic syndrome including short stature, skeletal osteopenia and dysplasia, optic atrophy, and a variable immunological, cutaneous, muscular, and neurological abnormalities. Hemizygous variants in CUL4B cause syndromic X-linked intellectual disability characterized by limitations in intellectual functions, developmental delays in gait, cognitive, and speech functioning, and other features including short stature, dysmorphism, and cerebral malformations. In this study, we report on a 4.5-month-old preterm infant with a complex phenotype mainly characterized by placental-related severe intrauterine growth restriction, post-natal growth failure with spontaneous bone fractures, which led to a suspicion of osteogenesis imperfecta, and lethal bronchopulmonary dysplasia with pulmonary hypertension. Whole exome sequencing identified compound heterozygosity for a known frameshift and a novel missense variant in NBAS and hemizygosity for a known CUL4B nonsense mutation. In vitro functional studies on the novel NBAS missense substitution demonstrated altered Golgi-to-endoplasmic reticulum retrograde vesicular trafficking and reduced collagen secretion, likely explaining part of the patient's phenotype. We also provided a comprehensive overview of the phenotypic features of NBAS and CUL4B deficiency, thus updating the recently emerging NBAS genotype-phenotype correlations. Our findings highlight the power of a genome-first approach for an early diagnosis of complex phenotypes.

Red blood cell transfusion in preterm infants: restrictive versus liberal policy.

Preterm neonates represent a category of patients with high transfusion needs. Ideally, red blood cells (RBC) transfusion should be tailored to the individual requirements of the single infant. However, despite the progress in neonatal transfusion medicine, many controversies still remain, and the decision on whether to transfuse or not is often made on empirical basis, with large variation in transfusion practices among neonatologists. Recently, a few clinical trials have been performed with the aim to compare the risk/benefit ratio of restrictive versus liberal transfusion criteria. Most of the studies failed to demonstrate significant differences in short-term outcomes, suggesting that the restrictive criteria may reduce the need for transfusion and the related side effects. Neurodevelopmental long-term outcome seemed more favorable in the liberal group at a first evaluation, especially for boys, and significantly better in the restrictive group at a later clinical investigation. Magnetic resonance imaging scans, performed at an average age of 12 years, showed that intracranial volume was substantially smaller in the liberal group compared with controls. When sex effects were evaluated, the girls in the liberal group had the most significant abnormalities. In conclusion, when preventive measures, as favoring cord clamping delay or cord milking, ensuring optimal nutrition, and minimizing phlebotomy losses, fail to avoid the need for transfusion, it is preferable to adopt restrictive criteria.