Pathogenic diversification of the gut commensal Providencia alcalifaciens via acquisition of a second type III secretion system.

Providencia alcalifaciens is a Gram-negative bacterium found in a wide variety of water and land environments and organisms. It has been isolated as part of the gut microbiome of animals and insects, as well as from stool samples of patients with diarrhea. Specific P. alcalifaciens strains encode gene homologs of virulence factors found in other pathogenic members of the same Enterobacterales order, such as Salmonella enterica serovar Typhimurium and Shigella flexneri. Whether these genes are also pathogenic determinants in P. alcalifaciens is not known. Here we have used P. alcalifaciens 205/92, a clinical isolate, with in vitro and in vivo infection models to investigate P. alcalifaciens -host interactions at the cellular level. Our particular focus was the role of two type III secretion systems (T3SS) belonging to the Inv-Mxi/Spa family. T3SS 1b is widespread in Providencia spp. and encoded on the chromosome. T3SS 1a is encoded on a large plasmid that is present in a subset of P. alcalifaciens strains, which are primarily isolates from diarrheal patients. Using a combination of electron and fluorescence microscopy and gentamicin protection assays we show that P. alcalifaciens 205/92 is internalized into eukaryotic cells, rapidly lyses its internalization vacuole and proliferates in the cytosol. This triggers caspase-4 dependent inflammasome responses in gut epithelial cells. The requirement for the T3SS 1a in entry, vacuole lysis and cytosolic proliferation is host-cell type specific, playing a more prominent role in human intestinal epithelial cells as compared to macrophages. In a bovine ligated intestinal loop model, P. alcalifaciens colonizes the intestinal mucosa, inducing mild epithelial damage with negligible fluid accumulation. No overt role for T3SS 1a or T3SS 1b was seen in the calf infection model. However, T3SS 1b was required for the rapid killing of Drosophila melanogaster . We propose that the acquisition of two T3SS by horizontal gene transfer has allowed P. alcalifaciens to diversify its host range, from a highly virulent pathogen of insects to an opportunistic gastrointestinal pathogen of animals.

Detection of SARS-CoV-2 BA.2.86 by lateral flow devices.

We evaluated the performance of 12 lateral flow devices by assessing their analytical sensitivity for SARS-CoV-2 variant BA.2.86. Kits from ACON, Orient Gene, Xiamen Biotime, Getein, and SureScreen detected variant BA.2.86 to sufficient sensitivity levels, comparable to those observed with previous Omicron variants. The stocks of lateral flow devices currently held by the UK government do not currently need changing for deployment for this variant.

Nusinersen by subcutaneous intrathecal catheter for symptomatic spinal muscular atrophy patients with complex spine anatomy.

INTRODUCTION/AIMS: Intrathecal administration of nusinersen is challenging in patients with spinal muscular atrophy (SMA) who have spine deformities or fusions. We prospectively studied the safety and efficacy of nusinersen administration via an indwelling subcutaneous intrathecal catheter (SIC) for SMA patients with advanced disease. METHODS: Seventeen participants commenced nusinersen therapy between 2.7 and 31.5 years of age and received 9 to 12 doses via SIC. Safety was assessed in all participants. A separate efficacy analysis comprised 11 nonambulatory, treatment-naive SMA patients (18.1 ± 6.8 years) with three SMN2 copies and complex spine anatomy. RESULTS: In the safety analysis, 14 treatment-related adverse events (AEs) occurred among 12 (71%) participants; all were related to the SIC and not nusinersen. Device-related AEs interfered with 2.5% of nusinersen doses. Four SICs (24%) required surgical revision due to mechanical malfunction with or without cerebrospinal fluid leak (n = 2), and one (6%) was removed due to Staphylococcus epidermidis meningitis. In the efficacy analysis, mean performance on the nine-hole peg test improved in dominant (15.9%, P = 0.012) and nondominant (19.0%, P = 0.008) hands and grip strength increased by 44.9% (P = 0.031). We observed no significant changes in motor scales, muscle force, pulmonary function, or SMA biomarkers. All participants in the efficacy cohort reported one or more subjective improvement(s) in endurance, purposeful hand use, arm strength, head control, and/or speech. DISCUSSION: For SMA patients with complex spine anatomy, the SIC allows for reliable outpatient administration of nusinersen that results in meaningful improvements in upper limb function, but introduces risks of technical malfunction and iatrogenic infection.

Sterile Compounding Knowledge, Skills, and Confidence Among Graduating Doctor of Pharmacy Students.

Objective. To determine whether the exposure to sterile compounding in the pharmacy curriculum produces Doctor of Pharmacy graduates who are both competent and confident in the area of sterile compounding, and to identify additional variables that may predict student performance.Methods. Participants were recruited from the fourth-year pharmacy class of 2018 at one university. The students were asked to complete a questionnaire assessing the following domains: demographics, confidence in compounding performance, prior experience, and theoretical knowledge. A written assessment was followed by a faculty-evaluated practicum in which the students were required to prepare two sterile products using a standardized rubric. Results were analyzed with a Student t test and linear regression to determine differences in performance based upon prior experience, confidence, and theoretical knowledge.Results. Overall, the 158 students performed well on the knowledge and skill examination, achieving an average total score of 89.8%. Of the 158 total participants, the 122 survey respondents had an overall mean confidence score of 2.9 on a four-point Likert scale, with 40.2% of students scoring in the confident or very confident range of the survey. In our analysis, we found that neither prior compounding experience or self-rated confidence were predictive of students' total score.Conclusion. The results of this study suggest that the inclusion of sterile compounding education and training in all four years of the pharmacy curriculum produces PharmD graduates who are competent, with varying levels of confidence in the area of sterile compounding.

Glutaric acidemia type 1: Treatment and outcome of 168 patients over three decades.

Glutaric acidemia type 1 (GA1) is a disorder of cerebral organic acid metabolism resulting from biallelic mutations of GCDH. Without treatment, GA1 causes striatal degeneration in >80% of affected children before two years of age. We analyzed clinical, biochemical, and developmental outcomes for 168 genotypically diverse GA1 patients managed at a single center over 31 years, here separated into three treatment cohorts: children in Cohort I (n = 60; DOB 2006-2019) were identified by newborn screening (NBS) and treated prospectively using a standardized protocol that included a lysine-free, arginine-enriched metabolic formula, enteral l-carnitine (100 mg/kg•day), and emergency intravenous (IV) infusions of dextrose, saline, and l-carnitine during illnesses; children in Cohort II (n = 57; DOB 1989-2018) were identified by NBS and treated with natural protein restriction (1.0-1.3 g/kg•day) and emergency IV infusions; children in Cohort III (n = 51; DOB 1973-2016) did not receive NBS or special diet. The incidence of striatal degeneration in Cohorts I, II, and III was 7%, 47%, and 90%, respectively (p < .0001). No neurologic injuries occurred after 19 months of age. Among uninjured children followed prospectively from birth (Cohort I), measures of growth, nutritional sufficiency, motor development, and cognitive function were normal. Adherence to metabolic formula and l-carnitine supplementation in Cohort I declined to 12% and 32%, respectively, by age 7 years. Cessation of strict dietary therapy altered plasma amino acid and carnitine concentrations but resulted in no serious adverse outcomes. In conclusion, neonatal diagnosis of GA1 coupled to management with lysine-free, arginine-enriched metabolic formula and emergency IV infusions during the first two years of life is safe and effective, preventing more than 90% of striatal injuries while supporting normal growth and psychomotor development. The need for dietary interventions and emergency IV therapies beyond early childhood is uncertain.

Branched-chain α-ketoacid dehydrogenase deficiency (maple syrup urine disease): Treatment, biomarkers, and outcomes.

Over the past three decades, we studied 184 individuals with 174 different molecular variants of branched-chain α-ketoacid dehydrogenase activity, and here delineate essential clinical and biochemical aspects of the maple syrup urine disease (MSUD) phenotype. We collected data about treatment, survival, hospitalization, metabolic control, and liver transplantation from patients with classic (i.e., severe; n = 176), intermediate (n = 6) and intermittent (n = 2) forms of MSUD. A total of 13,589 amino acid profiles were used to analyze leucine tolerance, amino acid homeostasis, estimated cerebral amino acid uptake, quantitative responses to anabolic therapy, and metabolic control after liver transplantation. Standard instruments were used to measure neuropsychiatric outcomes. Despite advances in clinical care, classic MSUD remains a morbid and potentially fatal disorder. Stringent dietary therapy maintains metabolic variables within acceptable limits but is challenging to implement, fails to restore appropriate concentration relationships among circulating amino acids, and does not fully prevent cognitive and psychiatric disabilities. Liver transplantation eliminates the need for a prescription diet and safeguards patients from life-threatening metabolic crises, but is associated with predictable morbidities and does not reverse pre-existing neurological sequelae. There is a critical unmet need for safe and effective disease-modifying therapies for MSUD which can be implemented early in life. The biochemistry and physiology of MSUD and its response to liver transplantation afford key insights into the design of new therapies based on gene replacement or editing.

Recessive GM3 synthase deficiency: Natural history, biochemistry, and therapeutic frontier.

GM3 synthase, encoded by ST3GAL5, initiates synthesis of all downstream cerebral gangliosides. Here, we present biochemical, functional, and natural history data from 50 individuals homozygous for a pathogenic ST3GAL5 c.862C>T founder allele (median age 8.1, range 0.7-30.5 years). GM3 and its derivatives were undetectable in plasma. Weight and head circumference were normal at birth and mean Apgar scores were 7.7 ±â€¯2.0 (1 min) and 8.9 ±â€¯0.5 (5 min). Somatic growth failure, progressive microcephaly, global developmental delay, visual inattentiveness, and dyskinetic movements developed within a few months of life. Infantile-onset epileptic encephalopathy was characterized by a slow, disorganized, high-voltage background, poor state transitions, absent posterior rhythm, and spike trains from multiple independent cortical foci; >90% of electrographic seizures were clinically silent. Hearing loss affected cochlea and central auditory pathways and 76% of children tested failed the newborn hearing screen. Development stagnated early in life; only 13 (26%) patients sat independently (median age 30 months), three (6%) learned to crawl, and none achieved reciprocal communication. Incessant irritability, often accompanied by insomnia, began during infancy and contributed to high parental stress. Despite catastrophic neurological dysfunction, neuroimaging showed only subtle or no destructive changes into late childhood and hospitalizations were surprisingly rare (0.2 per patient per year). Median survival was 23.5 years. Our observations corroborate findings from transgenic mice which indicate that gangliosides might have a limited role in embryonic neurodevelopment but become vital for postnatal brain growth and function. These results have critical implications for the design and implementation of ganglioside restitution therapies.

Preliminary Safety and Tolerability of a Novel Subcutaneous Intrathecal Catheter System for Repeated Outpatient Dosing of Nusinersen to Children and Adults With Spinal Muscular Atrophy.

BACKGROUND: Many patients with spinal muscular atrophy (SMA) who might benefit from intrathecal antisense oligonucleotide (nusinersen) therapy have scoliosis or spinal fusion that precludes safe drug delivery. To circumvent spinal pathology, we designed a novel subcutaneous intrathecal catheter (SIC) system by connecting an intrathecal catheter to an implantable infusion port. METHODS: Device safety and tolerability were tested in 10 SMA patients (age, 5.4 to 30.5 y; 80% with 3 copies of SMN2); each received 3 sequential doses of nusinersen (n=30 doses). Pretreatment disease burden was evaluated using the Revised Hammersmith Scale, dynamometry, National Institutes of Health pegboard, pulmonary function testing, electromyography, and 2 health-related quality of life tools. RESULTS: Device implantation took ≤2 hours and was well tolerated. All outpatient nusinersen doses were successfully administered via SIC within 20 minutes on the first attempt, and required no regional or systemic analgesia, cognitive distraction, ultrasound guidance, respiratory precautions, or sedation. Cerebrospinal fluid withdrawn from the SIC had normal levels of glucose and protein; cerebrospinal fluid white blood cells were slightly elevated in 2 (22%) of 9 specimens (median, 1 cell/µL; range, 0 to 12 cells/µL) and red blood cells were detected in 7 (78%) specimens (median, 4; range, 0 to 2930 cells/µL). DISCUSSION: Preliminary observations reveal the SIC to be relatively safe and well tolerated in SMA patients with advanced disease and spinal fusion. The SIC warrants further study and, if proven effective in larger trials of longer duration, could double the number of patients able to receive nusinersen worldwide while reducing administration costs 5- to 10-fold.

Genomic diagnostics within a medically underserved population: efficacy and implications.

PurposeWe integrated whole-exome sequencing (WES) and chromosomal microarray analysis (CMA) into a clinical workflow to serve an endogamous, uninsured, agrarian community.MethodsSeventy-nine probands (newborn to 49.8 years) who presented between 1998 and 2015 remained undiagnosed after biochemical and molecular investigations. We generated WES data for probands and family members and vetted variants through rephenotyping, segregation analyses, and population studies.ResultsThe most common presentation was neurological disease (64%). Seven (9%) probands were diagnosed by CMA. Family WES data were informative for 37 (51%) of the 72 remaining individuals, yielding a specific genetic diagnosis (n = 32) or revealing a novel molecular etiology (n = 5). For five (7%) additional subjects, negative WES decreased the likelihood of genetic disease. Compared to trio analysis, "family" WES (average seven exomes per proband) reduced filtered candidate variants from 22 ± 6 to 5 ± 3 per proband. Nineteen (51%) alleles were de novo and 17 (46%) inherited; the latter added to a population-based diagnostic panel. We found actionable secondary variants in 21 (4.2%) of 502 subjects, all of whom opted to be informed.ConclusionCMA and family-based WES streamline and economize diagnosis of rare genetic disorders, accelerate novel gene discovery, and create new opportunities for community-based screening and prevention in underserved populations.

Management of Congenital Heart Disease Associated with Ellis-van Creveld Short-rib Thoracic Dysplasia.

OBJECTIVE: To evaluate clinical outcome of patients with Ellis-van Creveld syndrome (EVC) in whom congenital heart disease (CHD) repair was delayed intentionally to reduce the risk of postoperative respiratory morbidity and mortality. STUDY DESIGN: This retrospective review of 51 EVC c.1886+5G>T homozygotes born between 2005 and 2014 focused on 18 subjects who underwent surgery for CHD, subdivided into early (mean, 1.3 months) vs delayed (mean, 50.1 months) repair. RESULTS: Growth trajectories differed between control subjects and patients with EVC, and CHD was associated with slower weight gain. Relative to controls, infants with EVC had a 40%-75% higher respiratory rates (independent of CHD) accompanied by signs of compensated respiratory acidosis. Blood gases and respiratory rates approached normal values by age 4 years. Hemodynamically significant CHD was present in 23 children, 18 (78%) of whom underwent surgical repair. Surgery was performed at 1.3 ± 1.3 months for children born between 2005 and 2009 (n = 9) and 50.1 ± 40.2 months (P = .009) for children born between 2010 and 2014 (n = 9). The latter had shorter postoperative mechanical ventilation (1.1 ± 2.4 days vs 49.6 ± 57.1 days; P = .075), shorter intensive care duration of stay (16 ± 24 days vs 48.6 ± 44.2 days; P = .155), and no postoperative tracheostomies (vs 60%; P = .028) or deaths (vs 44%; P = .082). CONCLUSION: Among children with EVC and possibly other short-rib thoracic dysplasias, delayed surgical repair of CHD reduces postoperative morbidity and improves survival. Respiratory rate serves as a simple indicator for optimal timing of surgical repair.

Severe Salt-Losing 3ß-Hydroxysteroid Dehydrogenase Deficiency: Treatment and Outcomes of HSD3B2 c.35G>A Homozygotes.

CONTEXT: 3-ß-hydroxysteroid dehydrogenase (HSD3B2) deficiency accounts for less than 5% of congenital adrenal hyperplasia worldwide, but is relatively common among the Old Order Amish of North America due to a HSD3B2 c.35G>A founder mutation. OBJECTIVE: We review clinical presentation, disease course, treatment, and outcomes of a genetically homogenous population of HSD3B2-deficient patients. DESIGN AND PARTICIPANTS: This was a retrospective case series: anthropometric, biochemical, and clinical data from 16 (six male) affected subjects (age, 7.2 ± 6.4 y) were compared to reference data from 12 age-matched unaffected siblings. SETTING: The setting was the Clinic for Special Children, a nonprofit rural community health center in Lancaster, Pennsylvania. MAIN OUTCOME MEASURES: The main outcome measures were growth, skeletal maturation, sexual development, blood pressure, glucocorticoid dose, pituitary-adrenal homeostasis, and long-term morbidity. RESULTS: Exogenous glucocorticoid requirement was dichotomous: a standard-dose group (n = 9) required 15.4 ± 4.9 mg/m(2)/d hydrocortisone equivalent, whereas a high-dose group required much larger and more variable doses (hydrocortisone equivalent, 37.8 ± 15.4 mg/m(2)/d) (P < .0001). Despite glucocorticoid doses 2-fold higher than the standard-dose group, high-dose patients: 1) had ACTH, 17-hydroxypregnenolone, and dehydroepiandrosterone levels that were 10-fold, 20-fold, and 20-fold higher, respectively; 2) were exclusively affected by signs of sex steroid excess; and 3) tended to have more iatrogenic complications. CONCLUSIONS: Patients with HSD3B2 deficiency and 21-hydroxylase deficiency suffer similar morbid complications from under- and overtreatment, but HSD3B2 deficiency is associated with a distinctive pattern of sex steroid dysmetabolism. Disease- and treatment-related morbidities are almost exclusively observed among subjects who have a high exogenous glucocorticoid requirement.

Online virtual-patient cases versus traditional problem-based learning in advanced pharmacy practice experiences.

OBJECTIVE: To evaluate the efficacy of faculty-led problem-based learning (PBL) vs online simulated-patient case in fourth-year (P4) pharmacy students. DESIGN: Fourth-year pharmacy students were randomly assigned to participate in either online branched-case learning using a virtual simulation platform or a small-group discussion. Preexperience and postexperience student assessments and a survey instrument were completed. EVALUATION: While there were no significant differences in the preexperience test scores between the groups, there was a significant increase in scores in both the virtual-patient group and the PBL group between the preexperience and postexperience tests. The PBL group had higher postexperience test scores (74.8±11.7) than did the virtual-patient group (66.5±13.6) (p=0.001). CONCLUSION: The PBL method demonstrated significantly greater improvement in postexperience test scores than did the virtual-patient method. Both were successful learning methods, suggesting that a diverse approach to simulated patient cases may reach more student learning styles.

Initial experience with a dual-balloon catheter for the management of postpartum hemorrhage.

OBJECTIVE: When uterotonics fail to cause sustained uterine contractions and satisfactory control of hemorrhage after delivery, tamponade of the uterus can be effective in decreasing hemorrhage secondary to uterine atony. STUDY DESIGN: These data are from a postmarketing surveillance study of a novel dual-balloon catheter tamponade device, the Belfort-Dildy Obstetrical Tamponade System (ebb). RESULTS: A total of 57 women were enrolled: 55 women had the diagnosis of postpartum hemorrhage, and 51 women had uterine balloon placement within the uterine cavity. This study reports the outcomes in the 51 women who had uterine balloon placement within the uterine cavity for treatment of postpartum hemorrhage, as defined by the "Instructions for Use." We further assessed 4 subgroups: uterine atony only (n = 28 women), placentation abnormalities (n = 8 women), both uterine atony and placentation abnormalities (n = 9 women), and neither uterine atony nor placentation abnormalities (n = 6 women). The median (range) time interval between delivery and balloon placement was 2.2 hours (0.3-210 hours) for the entire cohort (n = 51 women) and 1.3 hours (0.5-7.0 hours) for the uterine atony only group (n = 28 women). Bleeding decreased in 22/51 of cases (43%), stopped in 28/51 of cases (55%), thus decreased or stopped in 50/51 of the cases (98%) after balloon placement. Nearly one-half (23/51) of all women required uterine balloon volumes of >500 mL to control bleeding. CONCLUSION: We conclude that uterine/vaginal balloon tamponade is very useful in the management of postpartum hemorrhage because of uterine atony and abnormal placentation.

Safety, efficacy and physiological actions of a lysine-free, arginine-rich formula to treat glutaryl-CoA dehydrogenase deficiency: focus on cerebral amino acid influx.

Striatal degeneration from glutaryl-CoA dehydrogenase deficiency (glutaric aciduria type 1, GA1) is associated with cerebral formation and entrapment of glutaryl-CoA and its derivatives that depend on cerebral lysine influx. In 2006 we designed a lysine-free study formula enriched with arginine to selectively block lysine transport across cerebral endothelia and thereby limit glutaryl-CoA production by brain. Between 2006 and present, we treated twelve consecutive children with study formula (LYSx group) while holding all other treatment practices constant. Clinical and biochemical outcomes were compared to 25 GA1 patients (PROx group) treated between 1995 and 2005 with natural protein restriction (dietary lysine/arginine ratio of 1.7±0.3 mg:mg). We used published kinetic parameters of the y+and LAT1 blood-brain barrier transporters to model the influx of amino acids into the brain. Arginine fortification to achieve a mean dietary lysine/arginine ratio of 0.7±0.2 mg:mg was neuroprotective. All 12 LYSx patients are physically and neurologically healthy after 28 aggregate patient-years of follow up (current ages 28±21 months) and there were no adverse events related to formula use. This represents a 36% reduction of neurological risk (95% confidence interval 14-52%, p=0.018) that we can directly attribute to altered amino acid intake. During the first year of life, 20% lower lysine intake and two-fold higher arginine intake by LYSx patients were associated with 50% lower plasma lysine, 3-fold lower plasma lysine/arginine concentration ratio, 42% lower mean calculated cerebral lysine influx, 54% higher calculated cerebral arginine influx, 15-26% higher calculated cerebral influx of several anaplerotic precursors (isoleucine, threonine, methionine, and leucine), 50% less 3-hydroxyglutarate excretion, and a 3-fold lower hospitalization rate (0.8 versus 2.3 hospitalizations per patient per year). The relationship between arginine fortification and plasma lysine indicates that transport competition exists at both cerebrovascular and gastrointestinal barriers, suggesting their co-administration is key to efficacy. Monitoring the ratio between lysine and arginine in diet and plasma may prove a useful strategy for treating children with GA1.

Erythrocyte pyruvate kinase deficiency in an old-order Amish cohort: longitudinal risk and disease management.

Pyruvate kinase deficiency is a chronic illness with age specific consequences. Newborns suffer life-threatening hemolytic crisis and hyperbilirubinemia. Adults are at risk for infections because of asplenia, pregnancy-related morbidity, and may suffer organ damage because of systemic iron overload. We describe 27 Old Order Amish patients (ages 8 months-52 years) homozygous for c.1436G>A mutations in PKLR. Each subject had a predictable neonatal course requiring packed red blood cell transfusions (30 ± 5 mL/kg) to control hemolytic disease and intensive phototherapy to prevent kernicterus. Hemochromatosis affected 29% (n = 4) of adult patients, who had inappropriately normal serum hepcidin (34.5 ± 12.7 ng/mL) and GDF-15 (595 ± 335pg/mL) relative to hyperferritinemia (769 ± 595 mg/dL). A high prevalence of HFE gene mutations exists in this population and may contribute to iron-related morbidity. Based on our observations, we present a strategy for long-term management of pyruvate kinase deficiency.

Identification of a sporozoite-specific antigen from Toxoplasma gondii.

Reduction of risk for human and food animal infection with Toxoplasma gondii is hampered by the lack of epidemiological data documenting the predominant routes of infection (oocyst vs. tissue cyst consumption) in horizontally transmitted toxoplasmosis. Existing serological assays can determine previous exposure to the parasite, but not the route of infection. We have used difference gel electrophoresis, in combination with tandem mass spectroscopy and Western blot, to identify a sporozoite-specific protein (T. gondii embryogenesis-related protein [TgERP]), which elicited antibody and differentiated oocyst- versus tissue cyst-induced infection in pigs and mice. The recombinant protein was selected from a cDNA library constructed from T. gondii sporozoites; this protein was used in Western blots and probed with sera from T. gondii -infected humans. Serum antibody to TgERP was detected in humans within 6-8 mo of initial oocyst-acquired infection. Of 163 individuals in the acute stage of infection (anti- T. gondii IgM detected in sera, or < 30 in the IgG avidity test), 103 (63.2%) had detectable antibodies that reacted with TgERP. Of 176 individuals with unknown infection route and in the chronic stage of infection (no anti- T. gondii IgM detected in sera, or > 30 in the IgG avidity test), antibody to TgERP was detected in 31 (17.6%). None of the 132 uninfected individuals tested had detectable antibody to TgERP. These data suggest that TgERP may be useful in detecting exposure to sporozoites in early T. gondii infection and implicates oocysts as the agent of infection.

Classical maple syrup urine disease and brain development: principles of management and formula design.

Branched-chain ketoacid dehydrogenase deficiency results in complex and volatile metabolic derangements that threaten brain development. Treatment for classical maple syrup urine disease (MSUD) should address this underlying physiology while also protecting children from nutrient deficiencies. Based on a 20-year experience managing 79 patients, we designed a study formula to (1) optimize transport of seven amino acids (Tyr, Trp, His, Met, Thr, Gln, Phe) that compete with branched-chain amino acids (BCAAs) for entry into the brain via a common transporter (LAT1), (2) compensate for episodic depletions of glutamine, glutamate, and alanine caused by reverse transamination, and (3) correct deficiencies of omega-3 essential fatty acids, zinc, and selenium widespread among MSUD patients. The formula was enriched with LAT1 amino acid substrates, glutamine, alanine, zinc, selenium, and alpha-linolenic acid (18:3n-3). Fifteen Old Order Mennonite children were started on study formula between birth and 34 months of age and seen at least monthly in the office. Amino acid levels were checked once weekly and more often during illnesses. All children grew and developed normally over a period of 14-33 months. Energy demand, leucine tolerance, and protein accretion were tightly linked during periods of normal growth. Rapid shifts to net protein degradation occurred during illnesses. At baseline, most LAT1 substrates varied inversely with plasma leucine, and their calculated rates of brain uptake were 20-68% below normal. Treatment with study formula increased plasma concentrations of LAT1 substrates and normalized their calculated uptakes into the nervous system. Red cell membrane omega-3 polyunsaturated fatty acids and serum zinc and selenium levels increased on study formula. However, selenium and docosahexaenoic acid (22:6n-3) levels remained below normal. During the study period, hospitalizations decreased from 0.35 to 0.14 per patient per year. There were 28 hospitalizations managed with MSUD hyperalimentation solution; 86% were precipitated by common infections, especially vomiting and gastroenteritis. The large majority of catabolic illnesses were managed successfully at home using 'sick-day' formula and frequent amino acid monitoring. We conclude that the study formula is safe and effective for the treatment of classical MSUD. In principle, dietary enrichment protects the brain against deficiency of amino acids used for protein accretion, neurotransmitter synthesis, and methyl group transfer. Although the pathophysiology of MSUD can be addressed through rational formula design, this does not replace the need for vigilant clinical monitoring, frequent measurement of the complete amino acid profile, and ongoing dietary adjustments that match nutritional intake to the metabolic demands of growth and illness.

Immunologic and clinical features of 25 Amish patients with RMRP 70 A-->G cartilage hair hypoplasia.

Cartilage-hair hypoplasia is a short limbed skeletal dysplasia associated with impairments in host-defense. To better understand the clinical heterogeneity of this disorder, we studied 25 Amish patients with homozygous mutations in RMRP (RMRP 70 A>G). Despite mutation homogeneity, eight (32%) patients had severe or recurrent infections, two (8%) of these children underwent bone-marrow transplantation for combined immunodeficiency, and the remainder were healthy. Features distinguishing patients who underwent bone marrow transplantation from others were shorter birth length, and lower serum IgG, undetectable serum IgA, and elevated circulating NK cells before 2 years of age. Irrespective of clinical phenotype, most patients had lymphopenia and reduced lymphocyte proliferation to mitogens in vitro. Our cohort analysis suggests that many patients with cartilage-hair hypoplasia are at risk for infection susceptibility particularly during the first 2 years of life. Gauging this risk is difficult, and thus careful monitoring of all patients with cartilage-hair hypoplasia is warranted.

Polyhydramnios, megalencephaly and symptomatic epilepsy caused by a homozygous 7-kilobase deletion in LYK5.

We used single nucleotide polymorphism (SNP) microarrays to investigate the cause of a symptomatic epilepsy syndrome in a group of seven distantly related Old Order Mennonite children. Autozygosity mapping was inconclusive, but closer inspection of the data followed by formal SNP copy number analyses showed that all affected patients had homozygous deletions of a single SNP (rs721575) and their parents were hemizygous for this marker. The deleted SNP marked a larger deletion encompassing exons 9-13 of LYK5, which encodes STE20-related adaptor protein, a pseudokinase necessary for proper localization and function of serine/threonine kinase 11 (a.k.a. LKB1). Homozygous LYK5 deletions were associated with polyhydramnios, preterm labour and distinctive craniofacial features. Affected children had large heads, infantile-onset intractable multifocal seizures and severe psychomotor retardation. We designated this condition PMSE syndrome (polyhydramnios, megalencephaly and symptomatic epilepsy). Thirty-eight percent (N = 16) of affected children died during childhood (ages 7 months to 6 years) from medical complications of the disorder, which included status epilepticus, congestive heart failure due to atrial septal defect and hypernatremic dehydration due to diabetes insipidus. A single post-mortem neuropathological study revealed megalencephaly, ventriculomegaly, cytomegaly and extensive vacuolization and astrocytosis of white matter. There was abundant anti-phospho-ribosomal S6 labelling of large cells within the frontal cortex, basal ganglia, hippocampus and spinal cord, consistent with constitutive activation of the mammalian target of rapamycin (mTOR) signalling pathway in brain.