Prevalence and penetrance of ZFPM2 mutations and deletions causing congenital diaphragmatic hernia

Zinc finger protein, FOG2 family member 2 (ZFPM2) (previously named FOG2) gene defects result in the highly morbid congenital diaphragmatic hernia (CDH) in humans and animal models. In a cohort of 275 CDH patient exomes, we estimated the prevalence of damaging ZFPM2 mutations to be almost 5%. Genetic analysis of a multigenerational family identified a heritable intragenic ZFPM2 deletion with an estimated penetrance of 37.5%, which has important implications for genetic counseling. Similarly, a low penetrance ZFPM2 frameshift mutation was observed in a second multiplex family. Isolated CDH was the predominant phenotype observed in our ZFPM2 mutation patients. Findings from the patients described herein indicate that ZFPM2 point mutations or deletions are a recurring cause of CDH.

Congenital diaphragmatic hernia interval on chromosome 8p23.1 characterized by genetics and protein interaction networks

Chromosome 8p23.1 is a common hotspot associated with major congenital malformations, including congenital diaphragmatic hernia (CDH) and cardiac defects. We present findings from high-resolution arrays in patients who carry a loss (n = 18) or a gain (n = 1) of sub-band 8p23.1. We confirm a region involved in both diaphragmatic and heart malformations. Results from a novel CNVConnect algorithm, prioritizing protein-protein interactions between products of genes in the 8p23.1 hotspot and products of previously known CDH causing genes, implicated GATA4, NEIL2, and SOX7 in diaphragmatic defects. Sequence analysis of these genes in 226 chromosomally normal CDH patients, as well as in a small number of deletion 8p23.1 patients, showed rare unreported variants in the coding region; these may be contributing to the diaphragmatic phenotype. We also demonstrated that two of these three genes were expressed in the E11.5-12.5 primordial mouse diaphragm, the developmental stage at which CDH is thought to occur. This combination of bioinformatics and expression studies can be applied to other chromosomal hotspots, as well as private microdeletions or microduplications, to identify causative genes and their interaction networks.

Donnai-Barrow syndrome (DBS/FOAR) in a child with a homozygous LRP2 mutation due to complete chromosome 2 paternal isodisomy

Donnai-Barrow syndrome [Faciooculoacousticorenal (FOAR) syndrome; DBS/FOAR] is a rare autosomal recessive disorder resulting from mutations in the LRP2 gene located on chromosome 2q31.1. We report a unique DBS/FOAR patient homozygous for a 4-bp LRP2 deletion secondary to paternal uniparental isodisomy for chromosome 2. The propositus inherited the mutation from his heterozygous carrier father, whereas the mother carried only wild-type LRP2 alleles. This is the first case of DBS/FOAR resulting from uniparental disomy (UPD) and the fourth published case of any paternal UPD 2 ascertained through unmasking of an autosomal recessive disorder. The absence of clinical symptoms above and beyond the classical phenotype in this and the other disorders suggests that paternal chromosome 2 is unlikely to contain imprinted genes notably affecting either growth or development. This report highlights the importance of parental genotyping in order to give accurate genetic counseling for autosomal recessive disorders.

Mutations in LRP2, which encodes the multiligand receptor megalin, cause Donnai-Barrow and facio-oculo-acoustico-renal syndromes

Donnai-Barrow syndrome is associated with agenesis of the corpus callosum, congenital diaphragmatic hernia, facial dysmorphology, ocular anomalies, sensorineural hearing loss and developmental delay. By studying multiplex families, we mapped this disorder to chromosome 2q23.3-31.1 and identified LRP2 mutations in six families with Donnai-Barrow syndrome and one family with facio-oculo-acoustico-renal syndrome. LRP2 encodes megalin, a multiligand uptake receptor that regulates levels of diverse circulating compounds. This work implicates a pathway with potential pharmacological therapeutic targets.

Bacterial diversity in necrotizing ulcerative periodontitis in HIV-positive subjects

BACKGROUND

Necrotizing ulcerative periodontitis (NUP) is a painful and potentially debilitating affliction that affects about 2% to 6% of HIV-positive subjects. NUP may be caused by specific microorganisms that are presently unknown or by microbial species not usually thought to cause periodontal infections. The purpose of this study was to define the bacterial species associated with NUP in HIV-positive patients.

METHODS

16S rRNA bacterial genes of DNA isolated from subgingival plaque of 8 HIV-positive subjects with NUP were amplified by polymerase chain reaction (PCR) and cloned into Escherichia coli. The sequences of cloned inserts were used to determine species identity or closest relatives by comparison with known sequences. The microbial profiles in subgingival plaque of subjects with NUP, chronic periodontitis, and periodontal health were compared using a battery of over 200 oligonucleotide probes in a PCR-based, reverse-capture, checkerboard DNA-DNA hybridization assay.

RESULTS

Sequence analysis of over 400 clones revealed 108 species; 65 were "uncultivable" phylotypes, of which 26 were novel to NUP subjects. Species or phylotypes most commonly detected were Bulleidia extructa, Dialister, Fusobacterium, Selenomonas, Peptostreptococcus, Veillonella, and the phylum TM7. Based on sequence analysis and checkerboard analysis, NUP did not possess the classical periodontal pathogens such as Porphyromonas gingivalis. Otherwise, the microbial profiles of NUP and periodontitis had many similarities. The microbial profiles of subgingival plaque from periodontally healthy subjects were different and less complex in comparison to the profiles of both disease groups.

CONCLUSIONS

Certain species appear to be associated with health and periodontal diseases. The putative pathogens associated with periodontal disease in HIV-negative subjects are not associated with NUP in HIV-positive subjects.

The evaluation of a humidifying device for vitreoretinal surgery

AIM

To study the feasibility of humidifying air during vitreoretinal surgery and measure the water content of air before and after intraocular transit.

METHODS

The absolute water content of air was measured in a series of six eyes undergoing fluid-air exchange during macular hole surgery. Infrared absorption spectroscopy was used to determine the water content of the air infusing and exiting each eye. After baseline measurements for each eye were recorded, a second fluid-air exchange was performed and the effect of humidifying the air infusion was documented. The humidifying device used in this study was a prototype adapted from a commercially available respiratory humidifier and enables humidified air to be delivered at a controlled temperature.

RESULTS

The water content of air increased following intraocular transit, implying dehydration occurs from the intraocular surfaces. For a standard airline infusion the mean increase in water content of air egressing from an eye was 13.4 mg/l. Humidifying the air reduced the rate of water loss by nearly 90%.

CONCLUSIONS

Significant water losses can occur from eyes undergoing fluid-air exchange. Humidifying the infused air can substantially reduce the dehydrating effect during an air exchange. This outcome may have a beneficial effect in reducing cataract formation and visual field defects associated with macular hole surgery.

Endoscopic placement of jejunal feeding catheters in critically ill patients by a "push" technique

BACKGROUND

Enteral nutrition is less expensive and often preferred to parenteral nutrition in the critically ill or injured patient. Gastric feedings are poorly tolerated in some patients, however, and postpyloric access is frequently difficult to obtain. In this report, we describe our experience with a new technique for bedside endoscopic placement of small intestinal feeding tubes.

METHODS

Using both prospective and retrospective analysis, we studied our results with endoscopically placed postpyloric feeding tubes in intensive care unit (ICU) patients. In this method, a 7F nasobiliary tube is passed via an endoscope into the proximal small bowel by a "push" technique. We recorded the demographic data of the patients, the feeding regimens subsequently used for these patients, and the overall feasibility and complications of the procedures themselves.

RESULTS

The technique was performed on 71 occasions in 61 ICU patients. The entire procedure averaged 29 minutes in a prospectively evaluated subset of patients. Small intestinal cannulation was successful in every case, including cases in which fluoroscopic attempts had failed. No complications developed from placement of the feeding tubes.

CONCLUSION

This report demonstrates that our bedside method of endoscopic placement of proximal small-bowel feeding tubes may be safely and expediently performed in ICU patients. Although not yet formally compared with other techniques, this procedure may have some advantages over traditional methods of small-bowel feeding tube placement.

Malabsorption associated with surgical procedures and its treatment

Signs and symptoms of malabsorption after surgical procedures can be subtle and recognized late. This article reviews some of the more common surgical procedures potentially associated with malabsorption and suggests techniques of nutrition intervention. Early recognition, and preferably preventative care, should result in improved patient outcome.