A rapid and non-invasive proteomic analysis using DBS and buccal swab for multiplexed second-tier screening of Pompe disease and Mucopolysaccharidosis type I

PURPOSE

Current newborn screening programs for Pompe disease (PD) and mucopolysaccharidosis type I (MPS I) suffer from a high false positive rate and long turnaround time for clinical follow up. This study aimed to develop a novel proteomics-based assay for rapid and accurate second-tier screening of PD and MPS I. A fast turnaround assay would enable the identification of severe cases who need immediate clinical follow up and treatment.

METHODS

We developed an immunocapture coupled with mass spectrometry-based proteomics (Immuno-SRM) assay to quantify GAA and IDUA proteins in dried blood spots (DBS) and buccal swabs. Sensitivity, linearity, reproducibility, and protein concentration range in healthy control samples were determined. Clinical performance was evaluated in known PD and MPS I patients as well as pseudodeficiency and carrier cases.

RESULTS

Using three 3.2 mm punches (~13.1 μL of blood) of DBS, the assay showed reproducible and sensitive quantification of GAA and IDUA. Both proteins can also be quantified in buccal swabs with high reproducibility and sensitivity. Infantile onset Pompe disease (IOPD) and severe MPS I cases are readily identifiable due to the absence of GAA and IDUA, respectively. In addition, late onset Pompe disease (LOPD) and attenuated MPS I patients showed much reduced levels of the target protein. By contrast, pseudodeficiency and carrier cases exhibited significant higher target protein levels compared to true patients.

CONCLUSION

Direct quantification of endogenous GAA and IDUA peptides in DBS by Immuno-SRM can be used for second-tier screening to rapidly identify severe PD and MPS I patients with a turnaround time of <1 week. Such patients could benefit from immediate clinical follow up and possibly earlier treatment.

"Doctors can read about it, they can know about it, but they've never lived with it": How parents use social media throughout the diagnostic odyssey

Parents of children with undiagnosed conditions struggle to obtain information about how to treat and support their children. It can be particularly challenging to find communities and other parents who share their experiences and can provide emotional and informational support. This study sought to characterize how parents use social media, both throughout the diagnostic odyssey and post-diagnosis, to meet their informational, social, and emotional support needs. We conducted qualitative semi-structured interviews with 14 parents from the Stanford site of the Undiagnosed Diseases Network (UDN), including five whose children had received a diagnosis through study participation. Interview recordings were analyzed using inductive, team-based coding and thematic analysis based in grounded theory using Dedoose qualitative analysis software. Through this process, we identified four key themes related to social media use. First, parents struggled to find the "right" community, often seeking out groups of similar patients based on symptoms or similar conditions. Second, though they found much valuable information through social media about caring for their child, they also struggled to interpret the relevance of the information to their own child's condition. Third, the social support and access to other patients' and families' lived experiences were described as both highly valued and emotionally challenging, particularly in the case of poor outcomes for similar families. Finally, parents expressed the need to balance concerns about their child's privacy with the value of transparency and data sharing for diagnosis. Our results suggest that the needs and experiences of undiagnosed patients and families differ from those with diagnosed diseases and highlight the need for support in best utilizing social media resources at different stages of the diagnostic odyssey.

Targeted long-read sequencing identifies missing disease-causing variation

Despite widespread clinical genetic testing, many individuals with suspected genetic conditions lack a precise diagnosis, limiting their opportunity to take advantage of state-of-the-art treatments. In some cases, testing reveals difficult-to-evaluate structural differences, candidate variants that do not fully explain the phenotype, single pathogenic variants in recessive disorders, or no variants in genes of interest. Thus, there is a need for better tools to identify a precise genetic diagnosis in individuals when conventional testing approaches have been exhausted. We performed targeted long-read sequencing (T-LRS) using adaptive sampling on the Oxford Nanopore platform on 40 individuals, 10 of whom lacked a complete molecular diagnosis. We computationally targeted up to 151 Mbp of sequence per individual and searched for pathogenic substitutions, structural variants, and methylation differences using a single data source. We detected all genomic aberrations-including single-nucleotide variants, copy number changes, repeat expansions, and methylation differences-identified by prior clinical testing. In 8/8 individuals with complex structural rearrangements, T-LRS enabled more precise resolution of the mutation, leading to changes in clinical management in one case. In ten individuals with suspected Mendelian conditions lacking a precise genetic diagnosis, T-LRS identified pathogenic or likely pathogenic variants in six and variants of uncertain significance in two others. T-LRS accurately identifies pathogenic structural variants, resolves complex rearrangements, and identifies Mendelian variants not detected by other technologies. T-LRS represents an efficient and cost-effective strategy to evaluate high-priority genes and regions or complex clinical testing results.

Evaluation of methods for calculating maximum allowable standing height in amputees competing in Paralympic athletics

The International Paralympic Committee has a maximum allowable standing height (MASH) rule that limits stature to a pre-trauma estimation. The MASH rule reduces the probability that bilateral lower limb amputees use disproportionately long prostheses in competition. Although there are several methods for estimating stature, the validity of these methods has not been compared. To identify the most appropriate method for the MASH rule, this study aimed to compare the criterion validity of estimations resulting from the current method, the Contini method, and four Canda methods (Canda-1, Canda-2, Canda-3, and Canda-4). Stature, ulna length, demispan, sitting height, thigh length, upper arm length, and forearm length measurements in 31 males and 30 females were used to calculate the respective estimation for each method. Results showed that Canda-1 (based on four anthropometric variables) produced the smallest error and best fitted the data in males and females. The current method was associated with the largest error of those tests because it increasingly overestimated height in people with smaller stature. The results suggest that the set of Canda equations provide a more valid MASH estimation in people with a range of upper limb and bilateral lower limb amputations compared with the current method.

Effects of BG9719 (CVT-124), an A1-adenosine receptor antagonist, and furosemide on glomerular filtration rate and natriuresis in patients with congestive heart failure

OBJECTIVES

To determine the effects of furosemide and the selective A1 adenosine receptor BG9719 on renal function in patients with congestive heart failure (CHF).

BACKGROUND

Studies suggest that adenosine may affect renal function by various mechanisms, but the effects of blockade of this system in humans is unknown. In addition, the effects of a therapeutic dose of furosemide on glomerular filtration rate (GFR) and renal plasma flow (RPF) in heart failure patients are controversial.

METHODS

On different days, 12 patients received placebo, BG9719 and furosemide. Glomerular filtration rate, RPF and sodium and water excretion were assessed immediately following drug administration.

RESULTS

Glomerular filtration rate was 84 +/- 23 ml/min/1.73m2 after receiving placebo, 82 +/- 24 following BG9719 administration and a decreased (p < 0.005) 63 +/- 18 following furosemide. Renal plasma flow was unchanged at 293 +/- 124 ml/min/1.73m2 on placebo, 334 +/- 155 after receiving BG9719 and 374 +/- 231 after receiving furosemide. Sodium excretion increased from 8 +/- 8 mEq following placebo administration to 37 +/- 26 mEq following BG9719 administration. In the six patients in whom it was measured, sodium excretion was 104 +/- 78 mEq following furosemide administration.

CONCLUSIONS

Natriuresis is effectively induced by both furosemide and the adenosine A1 antagonist BG9719 in patients with CHF. Doses of the two drugs used in this study did not cause equivalent sodium and water excretion but only furosemide decreased GFR. These data suggest that adenosine is an important determinant of renal function in patients with heart failure.

Structure of keyhole limpet hemocyanin type 1 (KLH1) at 15 A resolution by electron cryomicroscopy and angular reconstitution

A three-dimensional reconstruction of keyhole limpet hemocyanin type 1 (KLH1) has been obtained using electron cryomicroscopy at liquid helium temperatures and single particle image processing. The use of a high-contrast embedding medium, 1% (w/v) glucose and 2% (w/v) ammonium molybdate (pH 7.0), enables high-resolution electron micrographs to be recorded close to focus, i.e. with excellent transfer of high-resolution information, while maintaining enough image contrast to localise the individual macromolecules in the images. When low-pass filtered to approximately 45 A resolution, the new 15 A resolution reconstruction is very similar to the earlier reconstructions of gastropodan hemocyanins of specimens embedded in vitreous ice. The map shows much detail and reveals many new symmetry elements in this very large cylindrical molluscan hemocyanin. The full KLH1 didecamer has D5 pointgroup symmetry, yet within the KLH1 decameric half-molecules local 2-fold axes have emerged that make the wall of the KLH1 decamer, in spite of its having an exact C5 symmetry only, resemble the D5-symmetric wall of the decameric cephalopod hemocyanins. In fact, the outside of each tier of this six-tiered gastropodan hemocyanin was found to have an approximate D5 symmetry. Local 2-fold axes also relate the "functional units" within the dimeric "morphological units" of the wall and the collar areas of the 8 MDa KLH1 molecule. Certain local-symmetry-related surface motifs may be present up to 60 times on the outside wall of this highly symmetric cylindrical hemocyanin. Keyhole limpet hemocyanin is used clinically as an immunostimulant. The very strong immune reaction elicited by this hemocyanin may be associated with its intricate hierarchy of local-symmetry components.

Predictability of magnetic resonance imaging in differentiation of orbital lymphoma from orbital inflammatory syndrome

Twenty-two patients with clinical presentations of either orbital lymphoma or orbital inflammatory syndrome (OIS) involving 25 orbits were examined by magnetic resonance imaging (MRI) before biopsy. To determine whether MRI adds specificity to radiographic diagnosis, the MRI signal characteristics of all tumors were examined. Attention was focused on the signal intensity of each tumor on T1- and T2-weighted images. In nine of 12 (75%) orbital lymphomas, the tumors appeared hyperintense to fat on T2-weighted images and became brighter relative to their appearance on T1-weighted images. In 11 of 13 (85%) orbital infiltrates with OIS, the tumors appeared isointense to fat on T2-weighted images and became slightly darker or unchanged relative to their appearance on T1-weighted images. Tumor density and homogeneity were fairly similar in all 25 lesions and were therefore not useful for further differentiation. Similarly, the presence of moderate enhancement with gadopentetate dimeglumine was seen in all but one tumor, and it was therefore not useful for further differentiation.

Prevalence of scoliosis in neurofibromatosis

Experience in a comprehensive, multispecialty neurofibromatosis clinic leads the authors to suggest that the association of spinal deformity with neurofibromatosis is less frequent than usually assumed. Previously reported statistics may be partly attributed to preselection of patients seen by spinal surgeons, and to the predominant referral of patients having severe manifestations of neurofibromatosis. A diagnosis of neurofibromatosis 1, based on National Institutes of Health criteria, is confirmed for two hundred twenty patients at the clinic. Twenty-three of these patients have structural scoliosis. Nine patients have idiopathic type curves, eight have dystrophic scoliosis, four have dystrophic kyphoscoliosis, and two have dystrophic lordoscoliosis. The authors believe that 10% is representative of the true prevalence of spinal deformity in an otherwise unselected cross section of neurofibromatosis patients.

Clinical, morphologic, and cytogenetic characteristics of patients with lymphoid malignancies characterized by both t(14;18)(q32;q21) and t(8;14)(q24;q32) or t(8;22)(q24;q11)

Six patients with an aggressive leukemia/lymphoma disorder had a t(14;18) as well as either a t(8;14) (three patients) or a t(8;22) (three patients). Leukemia cells from all three patients with the t(8;22) had a mature B cell phenotype (Smlg + and TdT-), whereas two of three patients with the t(8;14) had a pre-B phenotype and were Smlg-. None of the patients with the t(8;22) had a prior history of follicular lymphoma, whereas two of the three patients with the t(8;14) had had a follicular lymphoma. The clinical, cytogenetic, and morphologic characteristics of these six patients along with eight previously reported cases with both the t(14;18) and the t(8;14), the t(8;22) or the t(2;8) are discussed.

Images of purple membrane at 2.8 A resolution obtained by cryo-electron microscopy

Improvements in technique have produced electron micrographs of purple membrane that provide, after computer analysis, reproducibly measurable diffraction peaks extending to 2.8 A (1 A = 0.1 nm). The improvements include better specimen preparation, a more stable cryo-electron microscope with better alignment and the addition of an image-processing step, which gives weights to local areas of the image according to the local strength of the periodic component of the image. These improvements have enabled the calculation of a directly phased projection map at 2.8 A resolution.