Cellaca® PLX image cytometer as an alternative for immunophenotyping, GFP/RFP transfection efficiencies, and apoptosis analysis.

Cell and gene therapy is a fast-growing field for cancer therapeutics requiring reliable instrumentation and technologies. Key parameters essential for satisfying Chemistry Manufacturing and Controls criteria standards are routinely performed using flow cytometry. Recently, image cytometry was developed for cell characterization and cell-based assays but had not yet demonstrated sufficient sensitivity for surface marker detection. We developed the Cellaca® PLX image cytometry system and the respective methodologies required for immunophenotyping, GFP and RFP transfection/transduction efficiencies, and cell health analyses for routine cell characterization. All samples tested were compared directly to results from the CytoFLEX flow cytometer. PBMCs were stained with T-cell surface markers for immunophenotyping, and results show highly comparable CD3, CD4, and CD8 populations (within 5 %). GFP- or RFP-expressing cell lines were analyzed for transfection/transduction efficiencies, and the percentage positive cells and respective viabilities were equivalent on both systems. Staurosporine-treated Jurkat cells were stained for apoptotic markers, where annexin V and caspase-3 positive cells were within 5 % comparing both instruments. The proposed system may provide a complementary tool for performing routine cell-based experiments with improved efficiency and sensitivity compared to prior image cytometers, which may be significantly valuable to the cell and gene therapy field.

Effects of mutant lamins on nucleo-cytoskeletal coupling in Drosophila models of LMNA muscular dystrophy.

The nuclei of multinucleated skeletal muscles experience substantial external force during development and muscle contraction. Protection from such forces is partly provided by lamins, intermediate filaments that form a scaffold lining the inner nuclear membrane. Lamins play a myriad of roles, including maintenance of nuclear shape and stability, mediation of nuclear mechanoresponses, and nucleo-cytoskeletal coupling. Herein, we investigate how disease-causing mutant lamins alter myonuclear properties in response to mechanical force. This was accomplished via a novel application of a micropipette harpooning assay applied to larval body wall muscles of Drosophila models of lamin-associated muscular dystrophy. The assay enables the measurement of both nuclear deformability and intracellular force transmission between the cytoskeleton and nuclear interior in intact muscle fibers. Our studies revealed that specific mutant lamins increase nuclear deformability while other mutant lamins cause nucleo-cytoskeletal coupling defects, which were associated with loss of microtubular nuclear caging. We found that microtubule caging of the nucleus depended on Msp300, a KASH domain protein that is a component of the linker of nucleoskeleton and cytoskeleton (LINC) complex. Taken together, these findings identified residues in lamins required for connecting the nucleus to the cytoskeleton and suggest that not all muscle disease-causing mutant lamins produce similar defects in subcellular mechanics.

Olig2 defines a subset of neural stem cells that produce specific olfactory bulb interneuron subtypes in the subventricular zone of adult mice.

Distinct neural stem cells (NSCs) reside in different regions of the subventricular zone (SVZ) and generate multiple olfactory bulb (OB) interneuron subtypes in the adult brain. However, the molecular mechanisms underlying such NSC heterogeneity remain largely unknown. Here, we show that the basic helix-loop-helix transcription factor Olig2 defines a subset of NSCs in the early postnatal and adult SVZ. Olig2-expressing NSCs exist broadly but are most enriched in the ventral SVZ along the dorsoventral axis complementary to dorsally enriched Gsx2-expressing NSCs. Comparisons of Olig2-expressing NSCs from early embryonic to adult stages using single cell transcriptomics reveal stepwise developmental changes in their cell cycle and metabolic properties. Genetic studies further show that cross-repression contributes to the mutually exclusive expression of Olig2 and Gsx2 in NSCs/progenitors during embryogenesis, but that their expression is regulated independently from each other in adult NSCs. Finally, lineage-tracing and conditional inactivation studies demonstrate that Olig2 plays an important role in the specification of OB interneuron subtypes. Altogether, our study demonstrates that Olig2 defines a unique subset of adult NSCs enriched in the ventral aspect of the adult SVZ.

Clinical characteristics and treatment requirements of children with autosomal recessive pseudohypoaldosteronism.

INTRODUCTION: Autosomal recessive forms of pseudohypoaldosteronism are caused by genetic defects in the epithelial sodium channel. Little is known about the long-term outcome and medication needs during childhood and adolescence. OBJECTIVE: This study reports a single-centre experience of children affected with this ultra-rare condition over a 37-year period. METHODS: We report the clinical presentation, growth, neuro-development, associated conditions, mortality and medication dosing and administration for 12 affected children from eight families. RESULTS: All children were presented within the first 2 weeks of life with life-threatening, severe hyperkalaemia and hyponatraemia. All parents were consanguineous and of South Asian, Middle Eastern or African ethnic origin. Eight children had homozygous mutations in the SCNN1A and SCNN1G genes, encoding the epithelial sodium channel subunits alpha and gamma, respectively, including one novel mutation. Three children died (25%) and two (16%) had severe neurological impairment post-cardiac arrest secondary to hyperkalaemia. One affected female had a successful pregnancy at the age of 28 years. CONCLUSION: Despite high mortality and morbidity in this condition, survival with normal physical and neurological outcome is possible, justifying intensive management to prevent electrolyte imbalance.

Peer Review of Paediatric Endocrine Services in the UK: A Template for Quality and Service Improvement.

BACKGROUND: Independent peer review of healthcare services can complement existing internal-, institutional-, and national-level regulatory mechanisms aimed at improving quality of healthcare. However, this has not been reported for paediatric endocrinology services in the UK. We aimed to test feasibility and acceptability through a first cycle of a national peer review of paediatric endocrine services. METHODS: Tertiary centres in paediatric endocrinology across the UK were assessed against 54 quality standards, developed by the British Society for Paediatric Endocrinology and Diabetes (BSPED) in five domains of healthcare by a team comprising paediatric endocrinologists and specialist nurses. The evaluation was supported by a self-assessment. A post-peer-review questionnaire was used as feedback. RESULTS: All 22 centres in the UK underwent independent peer review between 2011 and 2017. Each served a median population of 2.6 million (range 1-8 million) and offered 1,872 (range 779-6,738) outpatient consultations annually. A total of 43 (range 30-49) standards were met in combined evaluation of all centres. Variance of adherence for essential standards ranged from 52 to 97% at individual centres with 90% adherence demonstrated by 32% of centres. Post-review feedback showed 20/22 (95%) validating the utility of the peer review. CONCLUSIONS: The BSPED peer review of all UK centres providing paediatric endocrine services is shown to be feasible and provides a quality benchmark for replication by national services.

Exploring the Burden of X-Linked Hypophosphataemia: An Opportunistic Qualitative Study of Patient Statements Generated During a Technology Appraisal.

INTRODUCTION: Capturing the patient experience of living with a rare disease such as X-linked hypophosphataemia (XLH) is critical for a holistic understanding of the burden of a disease. The complexity of the disease coupled with the limited population makes elicitation of the patient burden methodologically challenging. This study used qualitative information direct from patient and caregiver statements to assess the burden of XLH. METHODS: A thematic analysis was conducted on statements received during a National Institute for Health and Care Excellence (NICE) online public open consultation from 15 June to 6 July 2018. Researchers and clinical experts generated themes and codes based on expected aspects of XLH burden. Statements were independently coded by two reviewers, adding additional codes as required, and analysed by frequency and co-reporting across age groups. RESULTS: The majority of responses were submitted from UK-based patients with some from the USA and Australia, and the statements related to children, adolescents and adults. The findings suggest that the greatest burden experienced by children is associated with conventional therapy, co-reported with dosing regimen, adherence, distress and pain. During adolescence, the burden becomes increasingly complex and multi-factorial, with an increasing psychological burden. In adults, conventional therapy co-reported with bone deformity and orthopaedic surgery, as well as pain, mobility, fatigue and dental problems, featured highly. DISCUSSION: Whilst our study was opportunistic in nature, it has highlighted the clear and distinctive evolution of the burden of XLH, transitioning from being therapy-oriented in childhood to multi-factorial in adolescence, and finally to adulthood with its high impact on need for other interventions, function and mobility. This qualitative thematic analysis enhances the understanding of the symptom and treatment burden of XLH.

Causes, patterns and severity of androgen excess in 487 consecutively recruited pre- and post-pubertal children.

Objective Androgen excess in childhood is a common presentation and may signify sinister underlying pathology. Data describing its patterns and severity are scarce, limiting the information available for clinical decision processes. Here, we examined the differential diagnostic value of serum DHEAS, androstenedione (A4) and testosterone in childhood androgen excess. Design Retrospective review of all children undergoing serum androgen measurement at a single center over 5 years. Methods Serum A4 and testosterone were measured by tandem mass spectrometry and DHEAS by immunoassay. Patients with at least one increased androgen underwent phenotyping by clinical notes review. Results In 487 children with simultaneous DHEAS, A4 and testosterone measurements, we identified 199 with androgen excess (140 pre- and 59 post-pubertal). Premature adrenarche (PA) was the most common pre-pubertal diagnosis (61%), characterized by DHEAS excess in 85%, while A4 and testosterone were only increased in 26 and 9% respectively. PCOS was diagnosed in 40% of post-pubertal subjects, presenting equally frequent with isolated excess of DHEAS (29%) or testosterone (25%) or increases in both A4 and testosterone (25%). CAH patients (6%) predominantly had A4 excess (86%); testosterone and DHEAS were increased in 50 and 33% respectively. Concentrations increased above the two-fold upper limit of normal were mostly observed in PA for serum DHEAS (>20-fold in the single case of adrenocortical carcinoma) and in CAH for serum androstenedione. Conclusions Patterns and severity of childhood androgen excess provide pointers to the underlying diagnosis and can be used to guide further investigations.

Bile acid metabolism is altered in those with insulin resistance after gestational diabetes mellitus.

BACKGROUND: Bile acids (BAs) are known mediators of glucose metabolism that are altered in type 2 diabetes mellitus (T2DM) and gestational diabetes mellitus (GDM). We hypothesised that post-prandial BA fractions are changed in women with Insulin resistance (IR) after recovery from GDM using homeostatic model assessment (HOMA-IR). METHODS: 45 women median age 44(31-47) with previous GDM, including 20 with HOMA-IR >2.8 and 25 age-matched controls with HOMA-IR ≤ 2.8 were studied. After an overnight fast, all underwent an oral glucose tolerance test. Blood samples were collected at baseline and every 30 min for 120 min and analysed for glucose on automated platform and for total BAs, their conjugates and fractions using liquid-chromatography tandem mass-spectrometry. Baseline samples were analysed for insulin on automated platform. Delta (Δ) change (difference between baseline and maximal post-prandial response) were calculated. Data is presented as median (IQR). RESULTS: Fasting primary and unconjugated BAs were higher in women with HOMA-IR >2.8 vs. those with HOMA-IR ≤ 2.8 [0.24 (0.16-0.33) vs 0.06(0.04-0.22) µmol/L and 0.91(0.56-1.84) µmol/L vs. 0.69(0.32-0.89) µmol/L respectively. ∆ taurine-conjugated BAs was higher in women with HOMA-IR ≤ 2.8 than those with HOMA-IR > 2.8 [0.33(0.20-0.54) vs 0.23(0.13-0.34) µmol/L]. Fasting glucose and non-12α-hydroxylated BAs were negatively correlated in women with HOMA-IR >2.8 (all p < 0.05). CONCLUSIONS: Following GDM, individuals with HOMA-IR >2.8 have altered conjugated and non-12α-hydroxylated fractions of BAs. It remains to be elucidated if the altered BA metabolism is a contributing factor to the pathogenesis or a consequence of GDM.

CYP3A4 mutation causes vitamin D-dependent rickets type 3.

Genetic forms of vitamin D-dependent rickets (VDDRs) are due to mutations impairing activation of vitamin D or decreasing vitamin D receptor responsiveness. Here we describe two unrelated patients with early-onset rickets, reduced serum levels of the vitamin D metabolites 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D, and deficient responsiveness to parent and activated forms of vitamin D. Neither patient had a mutation in any genes known to cause VDDR; however, using whole exome sequencing analysis, we identified a recurrent de novo missense mutation, c.902T>C (p.I301T), in CYP3A4 in both subjects that alters the conformation of substrate recognition site 4 (SRS-4). In vitro, the mutant CYP3A4 oxidized 1,25-dihydroxyvitamin D with 10-fold greater activity than WT CYP3A4 and 2-fold greater activity than CYP24A1, the principal inactivator of vitamin D metabolites. As CYP3A4 mutations have not previously been linked to rickets, these findings provide insight into vitamin D metabolism and demonstrate that accelerated inactivation of vitamin D metabolites represents a mechanism for vitamin D deficiency.

Efficacy and treatment costs of zoledronate versus pamidronate in paediatric osteoporosis.

Intravenous pamidronate has been used in the treatment of osteogenesis imperfecta (OI) in children for over 20 years. The more potent zoledronate is an attractive alternative as it is administered less frequently. This study compares the clinical efficacy of intravenous pamidronate (1.5 mg/kg/day over 2 days, every 3 months) versus zoledronate (0.05 mg/kg/dose every 6 months) in 40 children (20 per group) with mild to moderate OI and the treatment costs of the two drugs in a tertiary centre for children with osteoporosis. Lumbar spine bone mineral density and fracture rate did not differ between drug groups following 1 and 2 years of treatment, respectively. Total cost per treatment course per patient was £1157 for pamidronate and £498 for zoledronate. Therefore, zoledronate is a considerably cheaper alternative to pamidronate with comparable efficacy, resulting in substantial annual savings for healthcare providers and a more convenient option for patients due to fewer hospital visits.

Amalgamated Reference Data for Size-Adjusted Bone Densitometry Measurements in 3598 Children and Young Adults-the ALPHABET Study.

The increasing use of dual-energy X-ray absorptiometry (DXA) in children has led to the need for robust reference data for interpretation of scans in daily clinical practice. Such data need to be representative of the population being studied and be "future-proofed" to software and hardware upgrades. The aim was to combine all available pediatric DXA reference data from seven UK centers to create reference curves adjusted for age, sex, ethnicity, and body size to enable clinical application, using in vivo cross-calibration and making data back and forward compatible. Seven UK sites collected data on GE Lunar or Hologic Scanners between 1996 and 2012. Males and females aged 4 to 20 years were recruited (n = 3598). The split by ethnic group was white 2887; South Asian 385; black Afro-Caribbean 286; and mixed heritage 40. Scans of the total body and lumbar spine (L1 to L4 ) were obtained. The European Spine Phantom was used to cross-calibrate the 7 centers and 11 scanners. Reference curves were produced for L1 to L4 bone mineral apparent density (BMAD) and total body less head (TBLH) and L1 to L4 areal bone mineral density (aBMD) for GE Lunar Prodigy and iDXA (sex- and ethnic-specific) and for Hologic (sex-specific). Regression equations for TBLH BMC were produced using stepwise linear regression. Scans of 100 children were randomly selected to test backward and forward compatibility of software versions, up to version 15.0 for GE Lunar and Apex 4.1 for Hologic. For the first time, sex- and ethnic-specific reference curves for lumbar spine BMAD, aBMD, and TBLH aBMD are provided for both GE Lunar and Hologic scanners. These curves will facilitate interpretation of DXA data in children using methods recommended in ISCD guidelines. The databases have been created to allow future updates and analysis when more definitive evidence for the best method of fracture prediction in children is agreed. © 2016 American Society for Bone and Mineral Research.

An In Vitro Perfusion System to Enhance Outflow Studies in Mouse Eyes.

PURPOSE: The molecular mechanisms controlling aqueous humor (AQH) outflow and IOP need much further definition. The mouse is a powerful system for characterizing the mechanistic basis of AQH outflow. To enhance outflow studies in mice, we developed a perfusion system that is based on human anterior chamber perfusion culture systems. Our mouse system permits previously impractical experiments. METHODS: We engineered a computer-controlled, pump-based perfusion system with a platform for mounting whole dissected mouse eyes (minus lens and iris, ∼45% of drainage tissue is perfused). We tested the system's ability to monitor outflow and tested the effects of the outflow-elevating drug, Y27632, a rho-associated protein kinase (ROCK) inhibitor. Finally, we tested the system's ability to detect genetically determined decreases in outflow by determining if deficiency of the candidate genes Nos3 and Cav1 alter outflow. RESULTS: Using our system, the outflow facility (C) of C57BL/6J mouse eyes was found to range between 7.7 and 10.4 nl/minutes/mm Hg (corrected for whole eye). Our system readily detected a 74.4% Y27632-induced increase in C. The NOS3 inhibitor L-NG-nitroarginine methyl ester (L-NAME) and a Nos3 null mutation reduced C by 28.3% and 35.8%, respectively. Similarly, in Cav1 null eyes C was reduced by 47.8%. CONCLUSIONS: We engineered a unique perfusion system that can accurately measure changes in C. We then used the system to show that NOS3 and CAV1 are key components of mechanism(s) controlling outflow.

Absence of the ER Cation Channel TMEM38B/TRIC-B Disrupts Intracellular Calcium Homeostasis and Dysregulates Collagen Synthesis in Recessive Osteogenesis Imperfecta.

Recessive osteogenesis imperfecta (OI) is caused by defects in proteins involved in post-translational interactions with type I collagen. Recently, a novel form of moderately severe OI caused by null mutations in TMEM38B was identified. TMEM38B encodes the ER membrane monovalent cation channel, TRIC-B, proposed to counterbalance IP3R-mediated Ca2+ release from intracellular stores. The molecular mechanisms by which TMEM38B mutations cause OI are unknown. We identified 3 probands with recessive defects in TMEM38B. TRIC-B protein is undetectable in proband fibroblasts and osteoblasts, although reduced TMEM38B transcripts are present. TRIC-B deficiency causes impaired release of ER luminal Ca2+, associated with deficient store-operated calcium entry, although SERCA and IP3R have normal stability. Notably, steady state ER Ca2+ is unchanged in TRIC-B deficiency, supporting a role for TRIC-B in the kinetics of ER calcium depletion and recovery. The disturbed Ca2+ flux causes ER stress and increased BiP, and dysregulates synthesis of proband type I collagen at multiple steps. Collagen helical lysine hydroxylation is reduced, while telopeptide hydroxylation is increased, despite increased LH1 and decreased Ca2+-dependent FKBP65, respectively. Although PDI levels are maintained, procollagen chain assembly is delayed in proband cells. The resulting misfolded collagen is substantially retained in TRIC-B null cells, consistent with a 50-70% reduction in secreted collagen. Lower-stability forms of collagen that elude proteasomal degradation are not incorporated into extracellular matrix, which contains only normal stability collagen, resulting in matrix insufficiency. These data support a role for TRIC-B in intracellular Ca2+ homeostasis, and demonstrate that absence of TMEM38B causes OI by dysregulation of calcium flux kinetics in the ER, impacting multiple collagen-specific chaperones and modifying enzymes.

Estradiol: micrograms or milligrams.

UNLABELLED: Estrogen is used to induce puberty in peripubertal girls with hypogonadism. Although both synthetic and natural forms are available, along with different routes of administration, in the UK oral ethinyl estradiol and the low-dose oral contraceptive pill are commonly used as hormone replacement therapy for practical reasons. We present five peripubertal girls (aged 12.5-14.9 years) with hypogonadism (two with primary hypogonadism due to Turner syndrome and three with central (secondary) hypogonadism as part of multiple pituitary hormone deficiency) who for a variety of reasons have received milligram doses of estradiol (E2) in error for between 6 weeks and 6 months, instead of the expected microgram doses of ethinyl estradiol. Although there are no direct comparisons in peripubertal girls between synthetic and natural estrogens, all girls had vaginal bleeding whilst receiving the milligram doses and have ended up with reduced final heights, below the 9th centile in 1 and below the 2nd centile in 4. Whilst reduction in final height may be part of the underlying condition (especially in Turner syndrome) the two girls with height predictions performed prior to receiving the estrogen overdose have not achieved their predicted height. Estrogen is one of the few drugs which is available in both milligram and microgram formulations. Clinicians need to be alert to the possibility of patients receiving the wrong formulation and dosage in error. LEARNING POINTS: Girls with primary and secondary gonadal failure require assistance with pubertal induction.Although several different formulations and route of administration are available, for practical reasons, the majority of girls in the UK receive oral ethinyl estradiol.Estrogen preparations are available in both milligram and microgram formulations, with potential for receiving the wrong dose.Girls receiving milligram rather than microgram preparations all had vaginal bleeding and a short final height.

A Diagnostic Algorithm for Children with Low Alkaline Phosphatase Activities: Lessons Learned from Laboratory Screening for Hypophosphatasia.

OBJECTIVES: To explore the role of laboratory screening for hypophosphatasia and propose a diagnostic pathway for children with low serum alkaline phosphatase (ALP) activities. STUDY DESIGN: A retrospective hospital-based study over an 8-year period was conducted to identify children younger than 16 years of age with low ALP activity (<100 U/L). Study-positive patients were contacted for repeat sampling, and those with persistently low ALP had plasma pyridoxal-5'-phosphate and urinary phosphoethanolamine measured. RESULTS: Of 323 064 analyzed samples, 1526 had ALP activities <100 U/L. Most patients had transient hypophosphatasemia. Of 50 patients with last-recorded ALP <100 U/L, 32 were excluded given previous ALP >100 U/L. Eighteen were identified as study-positive. Of the 15 surviving children, 13 were traceable. Four had persistently low ALP activity on retesting, of whom 2 had raised pyridoxal-5'-phosphate and phosphoethanolamine concentrations and were subsequently tested for ALPL gene mutations; a 4-year-old asymptomatic girl with a novel homozygous ALPL missense mutation and a 23-year-old female with a heterozygous mutation. There was significant overlap in ALP activities between study-positive and 11 current patients with hypophosphatasia. We propose a diagnostic algorithm for children with low ALP activities based on clinical and biochemical variables. CONCLUSIONS: Patients with persistently low ALP activity require further clinical, biochemical, and radiological assessment for hypophosphatasia, even in the absence of clinical symptoms. The proposed diagnostic algorithm for children with low ALP will facilitate early detection of cases of hypophosphatasia, which, with the availability of enzyme replacement for hypophosphatasia, can be life-saving or avoid years of undiagnosed morbidity.

Early onset hearing loss in autosomal recessive hypophosphatemic rickets caused by loss of function mutation in ENPP1.

Autosomal recessive hypophosphatemic rickets 2 (ARHR2) is a rare form of renal tubular phosphate wasting disorder. Loss of function mutations of the ecto-nucleotide pyrophosphatase/pyrophosphodiesterase 1 gene (ENPP1) causes a wide spectrum of phenotypes, ranging from lethal generalized arterial calcification of infancy to hypophosphatemic rickets with hypertension. Hearing loss was not previously thought to be one of the features of the disease entities and was merely regarded as a complication rather than a part of the disease. We report two children who presented in mid to late childhood with progressive varus deformity of their legs due to hypophosphatemic rickets caused by mutations in the ENPP1 gene. Both children had evidence of progressive hearing loss requiring the use of hearing aids. This report of two unrelated infants with compound heterozygous mutations in ENPP1 and previously published cases confirms that mild to moderate hearing loss is frequently associated with ARHR2. Early onset conductive hearing loss may further distinguish the autosomal recessive ENPP1 related type from other types of hypophosphatemia.

Rapid skeletal turnover in a radiographic mimic of osteopetrosis.

Among the high bone mass disorders, the osteopetroses reflect osteoclast failure that prevents skeletal resorption and turnover, leading to reduced bone growth and modeling and characteristic histopathological and radiographic findings. We report an 11-year-old boy with a new syndrome that radiographically mimics osteopetrosis (OPT), but features rapid skeletal turnover. He presented at age 21 months with a parasellar, osteoclast-rich giant cell granuloma. Radiographs showed a dense skull, generalized osteosclerosis and cortical thickening, medullary cavity narrowing, and diminished modeling of tubular bones. His serum alkaline phosphatase was >5000 IU/L (normal <850 IU/L). After partial resection, the granuloma re-grew but then regressed and stabilized during 3 years of uncomplicated pamidronate treatment. His hyperphosphatasemia transiently diminished, but all bone turnover markers, especially those of apposition, remained elevated. Two years after pamidronate therapy stopped, bone mineral density (BMD) Z-scores reached +9.1 and +5.8 in the lumbar spine and hip, respectively, and iliac crest histopathology confirmed rapid bone remodeling. Serum multiplex biomarker profiling was striking for low sclerostin. Mutation analysis was negative for activation of lipoprotein receptor-related protein 4 (LRP4), LRP5, or TGFß1, and for defective sclerostin (SOST), osteoprotegerin (OPG), RANKL, RANK, SQSTM1, or sFRP1. Microarray showed no notable copy number variation. Studies of his nonconsanguineous parents were unremarkable. The etiology and pathogenesis of this unique syndrome are unknown.

IGFALS gene dosage effects on serum IGF-I and glucose metabolism, body composition, bone growth in length and width, and the pharmacokinetics of recombinant human IGF-I administration.

CONTEXT: Acid labile subunit (ALS) deficiency, caused by IGFALS mutations, is a subtype of primary IGF-I deficiency (PIGFD) and has been associated with insulin resistance (IR) and osteopenia. Whether patients respond to recombinant human IGF-I (rhIGF-I) is unknown. OBJECTIVE AND DESIGN: This study determined the 14-hour pharmacokinetic response of free and total IGF-I and IGF binding protein 3 (IGFBP-3) to a single sc dose of rhIGF-I (120 µg/kg) in four ALS-deficient patients, compared with severe PIGFD, moderate PIGFD, and controls. Intravenous glucose tolerance tests, fasting blood levels, dual-energy X-ray absorptiometry, peripheral quantitative computed tomography, and metacarpal radiogrammetry were performed in the four patients and 12 heterozygous family members. RESULTS: IGF-I and IGFBP-3 increased above baseline (P < .05) for 2.5 hours, returning to baseline 7 hours after rhIGF-I injection. Mean (SD) IGF-I Z-score increased by 2.49 (0.90), whereas IGFBP-3 Z-score increased by 0.57 (0.10) only. IGF-I elimination rates in ALS deficiency were similar, but the IGF-I increment was lower than those for severe PIGFD. Significant gene dosage effects were found for all IGF-I peptides, height, forearm muscle size, and metacarpal width. Bone analysis showed that ALS deficiency creates a phenotype of slender bones with normal size-corrected density. Abnormal glucose handling and IR was found in three of four patients and 6 of 12 carriers. CONCLUSIONS: These gene dosage effects demonstrate that one functional IGFALS allele is insufficient to maintain normal ALS levels, endocrine IGF-I action, full growth potential, muscle size, and periosteal expansion. Similar gene dosage effects may exist for parameters of IR. Despite similar IGF-I elimination compared with severe PIGFD, ALS-deficient patients cannot mount a similar response. Alternative ways of rhIGF-I administration should be sought.