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OBJECTIVE: Because the survival rate has increased for extremely low birth weight neonates, many have raised the concern that the rate of developmental disability among survivors will also increase. To address this concern, we analyzed changes over time in survival and major neurosensory impairment in a sample of extremely low birth weight infants born between July 1, 1979, and June 30, 1994. METHODS: The study sample included 513 infants with birth weights of 501 to 800 g who were cared for in either of the two neonatal intensive care units that serve a 17-county region in northwest North Carolina and who were born to mothers residing in that region. At 1 year of age (corrected for gestation), survivors were examined by a pediatrician and were tested using the Bayley Scales of Infant Development. Major neurosensory impairment was defined as cerebral palsy, a Bayley Mental Developmental Index <68, or blindness. A total of 209/216 (97%) of survivors were examined at 1 year of age. Epoch of birth was defined as follows: epoch 1, July 1, 1979 to June 30, 1984; epoch 2, July 1, 1984 to June 30, 1989; and epoch 3, July 1, 1989 to June 30, 1994. RESULTS: Survival rates for epochs 1, 2, and 3 were, respectively, 24/120 (20%), 63/175 (36%), and 129/218 (59%). In contrast, the proportions with a major neurosensory impairment did not increase over time; rates for successive epochs were 6/24 (25%), 17/61 (28%), and 26/124 (21%). Rates of cerebral palsy were 3/24 (13%), 12/61 (20%), and 9/124 (7%); rates of delayed mental development were 4/24 (17%), 12/61 (20%), and 17/124 (14%); and rates of blindness were 2/24 (8%), 0/62, and 5/124 (4%), respectively. CONCLUSIONS: This analysis suggests that the increasing survival of extremely low birth weight neonates since the late 1970s has not resulted in an increased rate of major developmental problems identifiable at 1 year of age. 相似文献
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Joana I. Meier Patricio A. Salazar Marek Ku
ka Robert William Davies Andreea Drau Ismael Alds Olivia Box Power Nicola J. Nadeau Jon R. Bridle Campbell Rolian Nicholas H. Barton W. Owen McMillan Chris D. Jiggins Yingguang Frank Chan 《Proceedings of the National Academy of Sciences of the United States of America》2021,118(25)
Genetic variation segregates as linked sets of variants or haplotypes. Haplotypes and linkage are central to genetics and underpin virtually all genetic and selection analysis. Yet, genomic data often omit haplotype information due to constraints in sequencing technologies. Here, we present “haplotagging,” a simple, low-cost linked-read sequencing technique that allows sequencing of hundreds of individuals while retaining linkage information. We apply haplotagging to construct megabase-size haplotypes for over 600 individual butterflies (Heliconius erato and H. melpomene), which form overlapping hybrid zones across an elevational gradient in Ecuador. Haplotagging identifies loci controlling distinctive high- and lowland wing color patterns. Divergent haplotypes are found at the same major loci in both species, while chromosome rearrangements show no parallelism. Remarkably, in both species, the geographic clines for the major wing-pattern loci are displaced by 18 km, leading to the rise of a novel hybrid morph in the center of the hybrid zone. We propose that shared warning signaling (Müllerian mimicry) may couple the cline shifts seen in both species and facilitate the parallel coemergence of a novel hybrid morph in both comimetic species. Our results show the power of efficient haplotyping methods when combined with large-scale sequencing data from natural populations.Understanding how changes in DNA sequence affect traits and shape the evolution of populations and species has been a defining goal in genetics and evolution (1–3). DNA is naturally organized in the genome as long molecules consisting of linked chromosome segments. Linkage is a core concept in genetics: in genetic mapping, geneticists map causal variants not by tracking the actual mutation but through many otherwise neutral and unremarkable linked variants. Likewise, the detection of selection relies on observing hitchhiking of linked variants rather than seeing the mutation itself. This recognition makes it all the more paradoxical that haplotype information is routinely omitted from most genomic studies as a technical compromise. Lacking haplotype information not only complicates analysis and ancestry reconstruction but also precludes detection of allele-specific expression (4) and chromosome rearrangements and reduces power to detect selective sweeps, even entirely missing them when multiple haplotypes sweep together (5). Instead of sequencing genomes as haplotypes, short-read sequencing produces 150-bp reads. Until long-read platforms become sufficiently accurate and affordable, this lack of haplotype context will continue to impact mapping and genomic studies, particularly those in nonmodel organisms.One way to simplify haplotype reconstruction and inference from sequencing data is to avoid discarding haplotype information in the first place. A promising emerging technique is linked-read (LR) sequencing (6–9), which preserves long-range information via molecular barcoding of long DNA molecules before sequencing. Individual short reads can then be linked via a shared barcode to reconstruct the original haplotype. However, existing options all suffer from high cost, poor scalability, and/or require custom sequencing primers or settings that have thus far prevented them from being applied as the default sequencing platform (SI Appendix, Tables S1 and S2). If LR sequencing could become scalable and affordable, it would significantly advance genetics by enabling the “haplotyping” of entire populations (i.e., the sequencing and systematic discovery of genomic variants as haplotypes in hundreds or even thousands of samples in model and nonmodel organisms alike).Here, we describe a solution called “haplotagging,” a simple and rapid protocol for LR sequencing. Importantly, haplotagging maintains full compatibility with standard Illumina sequencing and can easily scale to large populations with no extra costs. We demonstrate this in three steps. First, we show that direct haplotyping using haplotagging is robust in single human and mouse samples with known haplotypes (“phases”). Next, we show the feasibility of population haplotyping in 245 mice, even with very low-coverage LR sequencing. Finally, we apply haplotagging to investigate the emergence of a hybrid morph in a hybrid zone system in Ecuador featuring 670 individuals of two species of Heliconius butterflies. 相似文献
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Dror Y; Gallagher R; Wara DW; Colombe BW; Merino A; Benkerrou M; Cowan MJ 《Blood》1993,81(8):2021-2030
We describe our 9-year experience with lectin-treated T-cell-depleted haplocompatible parental bone marrow transplantation (BMT) for 24 patients with severe combined immunodeficiency disease (SCID). Nineteen of 21 evaluable patients had T-cell engraftment; 2 of 11 patients tested had B-cell and monocyte engraftment. Fourteen of 24 (58%) patients are alive 7 months to 9.8 years post-BMT. Seventeen of 24 patients received pretransplant conditioning with chemotherapy and/or total body irradiation, and 8 of 24 received more than one transplant. Patients who received conditioning had a survival rate of 61% versus 57% for those who received no conditioning. None received graft-versus- host disease (GVHD) prophylaxis and no patient had acute or chronic GVHD greater than grade I. Kinetics and follow-up of immune recovery were analyzed in 14 patients who are greater than 1 year from transplant. Half of the patients showed evidence of T-cell function by 3 months and normal T-cell function by 4 to 7 months post-BMT. On average, T-cell numbers and subsets became normal 10 to 12 months posttransplant. Recovery of B-cell function was more delayed, although in most patients B-cell numbers and IgM levels were normal by 12 months post-BMT. B-cell function, as determined by isohemagglutinin titers or specific antibodies to pneumococcal polysaccharide, keyhole limpet hemocyanin, or tetanus toxoid, became normal in 10 of 14 patients 2 to 8 years post-BMT. Seven of the 14 are off gammaglobulin therapy. Production of isohemagglutinins tended to predict recovery of antibody response to pneumococcal polysaccharide (P < .064). Based on these results, we believe that haplocompatible BMT is an effective, curative treatment for patients with SCID who lack an HLA-matched related donor. 相似文献
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