POS1155 THE INTERNATIONAL X-LINKED HYPOPHOSPHATAEMIA (XLH) REGISTRY: OVERVIEW OF THE DATA SET

Background

X-Linked Hypophosphataemia (XLH) is a rare, progressive, lifelong, hereditary renal tubule phosphate-wasting disorder characterised by a pathological increase in fibroblast growth factor 23 concentration/activity.1 Despite XLH being increasingly recognised as a chronic progressive disease, there are few data documenting its natural history or the impact of treatment on patient outcomes.2 The International XLH Registry was established to address this lack of information on XLH to help inform future clinical management. The Registry will collect data to characterise the treatment, burden of disease, disease progression and long-term outcomes of XLH.

Objectives

To provide an overview and status update of the International XLH Registry as of 31 December 2021.

Methods

The International XLH Registry (NCT03193476) was initiated in August 2017, aims to recruit 1,200 children and adults with XLH, and will run for 10 years. This Registry is an international, multicentre, non-interventional data collection programme and will provide the largest single dataset representing children and adults with XLH. To be eligible for inclusion in the registry, patients must meet all the following criteria:1) Male or female subjects of all ages; 2) Diagnosis of XLH with clinical, radiological, biochemical and/or genetic findings consistent with XLH. The Registry captures any treatment details and clinical outcome variables in patients with XLH and patients are followed for as long as informed consent (and assent, where applicable) and regulatory permissions are maintained. Only data collected during standard routine examinations are recorded within the Registry, and no specific examinations/data entries are mandated.

Parameters collected at baseline included demographics, medical and treatment history, and clinical presentation data. The conduct of the International XLH Registry is overseen by 17 Steering Committee physician members representing the region.

Results

As of 31 December 2021, 1,043 subjects diagnosed with XLH were enrolled from 88 hospital sites in 19 countries. The geographic distribution of subjects is as follows: Belgium n=29, Bulgaria n=7, Czech Republic n=8, Denmark n=23, France n=267, Germany n=79, Hungary n=11, Ireland n=5, Israel n=21, Italy n=88, The Netherlands n=26, Norway n=23, Portugal n=9, Slovakia n=5, Slovenia n=3, Spain n=55, Sweden n=43, Switzerland n=17, and the UK n=324. A further 30 sites are yet to enrol (including sites in Austria and Latvia). Overall, 400 adults (18–29y, n=116; 30–39y, n=81; 40–49y, n=95; 50–59y, n=58; ≥60y, n=50) and 620 paediatric subjects (<5y, n=138; 5–12y, n=321; 13–17y, n=161) have been enrolled (date of birth not reported, n=23). The majority of enrolled subjects are female (648 (62.1%), with 372 male (35.7%) and 23 for whom sex was not reported (2.2%). The quantity of data from the patients included in this Registry will enable ongoing snapshot and prospective analyses to be conducted over the coming years to answer research questions and inform clinical practice.

Conclusion

This International XLH Registry forms the largest dataset of subjects with XLH collected to date. Patients have been recruited from a wide geographical region and baseline demographics are consistent with a hereditary X-linked dominant disease. Information collected during the 10-year Registry duration will generate real-world evidence to help inform clinical practice throughout the region, with the aim of improving the care and quality of life of adults and children living with this debilitating disease.

References

[1]Haffner D, et al. Nat Rev Nephrol 2019;15(7):435–455.

[2]Padidela R, et al. Orphanet J Rare Dis. 2020; 15:172.

Acknowledgements

Authors acknowledge the contribution of all International XLH Registry Steering Committee members, and all the investigators participating in the International XLH Registry.

Disclosure of Interests

Gema Ariceta Speakers bureau: I have received honoraria for lectures, presentations, or educational events from Alexion Pharmaceuticals, Recordati Rare Disease, Advicenne, Chiesi, Kyowa Kirin, Consultant of: I have participated on Advisory Boards for Alexion Pharmaceuticals, Advicenne, Chiesi, Dicerna, and Alnylam., Jonathan Liu Employee of: Employee of Kyowa Kirin International, Angela Williams Employee of: Employee of Kyowa Kirin International, Sue Wood Employee of: Employee of Kyowa Kirin International, Dirk Schnabel Speakers bureau: I received an honorarium from various companies for scientific lectures (i.e. Ascendis, BioMarin, Ferring Pharma, Hexal / Sandoz, Ipsen Pharma, Kyowa Kirin, Merck Serono, Novo Nordisk), Consultant of: BioMarin, Kyowa Kirin

Maternal Weight Gain during Pregnancy and Somatic Classification of Neonates According to Birth Weight and Duration of Pregnancy Taking Account of Maternal Body Weight and Height

Background and Aim: The classification of weight gain during pregnancy and the somatic classification of neonates according to birth weight and duration of pregnancy can be done using percentile values. We aimed to compare such classifications using percentiles of the overall study population with classifications using percentiles that were calculated taking account of maternal height and weight. Material and Methods: Using data from the German Perinatal Survey (1995-2000, over 2.2 million singleton pregnancies) we classified weight gain during pregnancy as low (< 10th percentile), high (> 90th percentile), or medium (10th-90th percentile). Neonates were classified by birth weight as small for gestational age (SGA, < 10th percentile), large for gestational age (LGA, > 90th percentile), or appropriate for gestational age (AGA, 10th-90th percentile). Classifications were performed for 12 groups of women and their neonates formed according to maternal height and weight, either with the percentiles calculated from the total study population or with group-specific percentiles. Results: Using percentiles of the total study population there was large variability between the 12 groups in the proportions with low and high weight gain and in the proportions of SGA and LGA neonates. The variability was much lower when group-specific percentiles were used. Conclusions: Classifications of maternal weight gain during pregnancy and birth weight differ substantially, depending on whether percentiles calculated from the total study population or group-specific percentiles are used. The impact of using percentiles that take account of maternal anthropometric parameters for the medical care and health of neonates needs to be elucidated in future research.

First Report of Candidatus Liberibacter asiaticus Associated with Citrus Huanglongbing in California

Huanglongbing (HLB), also known as citrus greening, is one of the most destructive citrus diseases worldwide and is seen as a major threat to the multimillion dollar citrus industry in California. The vector of the two bacterial species associated with this disease, Candidatus Liberibacter asiaticus and Ca. L. americanus, is the Asian citrus psyllid (ACP), Diaphorina citri (4). ACP was detected in California in August of 2008 and has since been detected in nine counties in southern California. As part of a long term survey and testing program for the ACP carrying the HLB associated bacteria, groups of ACP nymphs and adults were submitted to the Jerry Dimitman Citrus Research Board/Citrus Pest and Disease Prevention Program Laboratory in Riverside, CA. In March 2012, DNA extracted using the Qiagen MagAttract 96 DNA plant kit (QIAGEN Inc., 27220 Turnberry Lane, Suite 200, Valencia, CA 91355) from a group of three ACP adults tested positive for Ca. L. asiaticus with the real-time PCR assay developed by Li et al. (4). ACP adults were collected from a residential citrus tree located in the Hacienda Heights area of Los Angeles County, California. The approximately 1.8 meter tall lemon tree had 23 graft unions, primarily of lemon (Citrus × meyeri) and pomelo (Citrus maxima) varieties. The tree was unthrifty, with yellow shoots and chlorotic leaves. Symptoms on the lemon and pomelo leaves included asymmetrical blotchy mottling, yellowing, and corking of the leaf veins, with the blotchy mottle more prominent in the pomelo leaves. Pomelo leaves appeared crinkled along the thickened veins. Lemon leaves had yellow veins and a few had islands of green tissue completely surrounded by yellow tissue. The entire tree was removed, cut into sections, bagged, and transported to the CDFA Plant Pest Diagnostics Lab for analysis. Two hundred milligrams of petiole and midrib tissue from leaves apical to each graft union was collected, and DNA from each sample was extracted using the Qiagen DNeasy plant mini kit. DNA extracted from both lemon and pomelo leaves tested positive for Ca. L. asiaticus using real-time PCR (4). A 1,160-bp fragment of the 16S ribosomal RNA gene was amplified from the insect and plant DNA extracts using conventional PCR with primers Ol1 and OI2c (2). A 703-bp fragment of the β-operon gene was amplified from the insect and plant extracts with primers A2 and J5 (1). The 16S rDNA fragments from the insect and plant respectively (GenBank Accession Nos. JX430434 and JX455745) and the β-operon fragments (JX430435 and JX455746) showed 100% identity with the corresponding regions of Ca. L. asiaticus (CP001677) strain psy 62. Our 16S rDNA sequence showed 98% identity with Ca. L. africanus (EU921620), 97% identity with Ca. L. solanacearum (HM246509), and 96% with Ca. L. americanus (FJ036892). In response to the detection of HLB, a 241 km2 quarantine area around the detection site was established. Surveys for ACP and symptomatic host plants within the HLB quarantine area are ongoing. To date, there have been no additional positive detections. In the United States, HLB was first detected in Florida in 2005 (4) and in Texas in January of 2012 (3). To our knowledge, this is the first confirmed report of Ca. L. asiaticus associated with HLB in California. References: (1) A. Hocquellet et al. Mol. Cell. Probes 13:373, 1999. (2) S. Jagoueix et al. Mol. Cell. Probes 10:43, 1996. (3) M. Kunta et al. Phytopathology 102:S4.66, 2012. (4) W. Li et al. J. Microbiol. Methods 66:104, 2006.

[Birth weight percentile values for girls and boys under consideration of maternal height]

There is a linear relationship between maternal height and birth weight. For each 1 cm increase in maternal height, birth weight increases by 16.7 g. Birth weight percentiles should be calculated by taking maternal height into account. We present birth weight percentile values for girls and boys born after 23-43 completed weeks of gestation for 5 maternal height groups. With these percentiles "genetically" small and "genetically" large, but healthy, neonates can be classified more adequately. The calculations are based on data of about 2.2 million singleton pregnancies from the German Perinatal Survey of 1995-2000.

Three-year growth hormone treatment in short children with X-linked hypophosphatemic rickets: effects on linear growth and body disproportion

CONTEXT

Children with X-linked hypophosphatemic rickets (XLH) are prone to progressive disproportionate stunting despite oral phosphate and vitamin D treatment.

OBJECTIVE

Our objective was to analyze the effects of GH treatment on stature and lengths of linear body segments in short children with XLH.

DESIGN, SETTINGS, AND PATIENTS

A 3-yr randomized controlled open-label GH study in short prepubertal children with XLH (n = 16) on phosphate and calcitriol treatment was conducted. A cohort of XLH patients (n = 76) on conservative treatment served as an XLH reference population.

MAIN OUTCOME MEASURES

Changes in SD scores (SDS) of stature and linear body segments, i.e. sitting height, leg and arm length, and sitting height index (i.e. ratio between sitting height and stature) were the main outcome measures.

RESULTS

XLH patients presented at time of enrollment with significant impairments of stature (-3.3 SDS) and linear body segments compared with healthy children. Leg length (-3.8 SDS) was most impaired, whereas sitting height (-1.7 SDS) was best preserved. The markedly elevated mean sitting height index (+3.3 SDS) reflected severe body disproportion. GH resulted in a sustained increase in linear growth (stature, +1.1 SDS; sitting height, +1.3 SDS; leg length, +0.8 SDS; arm length, +1.1 SDS; each P < 0.05 vs. baseline), whereas no significant changes were observed in controls. Mean height SDS at 3 yr did not significantly differ between groups. Sitting height index remained stable in both the GH-treated patients and in study controls but increased further in the XLH-reference population.

CONCLUSIONS

The 3-yr GH treatment improved linear growth without progression of body disproportion in short children with XLH.

The AFHSC-Division of GEIS Operations Predictive Surveillance Program: a multidisciplinary approach for the early detection and response to disease outbreaks

The Armed Forces Health Surveillance Center, Division of Global Emerging Infections Surveillance and Response System Operations (AFHSC-GEIS) initiated a coordinated, multidisciplinary program to link data sets and information derived from eco-climatic remote sensing activities, ecologic niche modeling, arthropod vector, animal disease-host/reservoir, and human disease surveillance for febrile illnesses, into a predictive surveillance program that generates advisories and alerts on emerging infectious disease outbreaks. The program’s ultimate goal is pro-active public health practice through pre-event preparedness, prevention and control, and response decision-making and prioritization. This multidisciplinary program is rooted in over 10 years experience in predictive surveillance for Rift Valley fever outbreaks in Eastern Africa. The AFHSC-GEIS Rift Valley fever project is based on the identification and use of disease-emergence critical detection points as reliable signals for increased outbreak risk. The AFHSC-GEIS predictive surveillance program has formalized the Rift Valley fever project into a structured template for extending predictive surveillance capability to other Department of Defense (DoD)-priority vector- and water-borne, and zoonotic diseases and geographic areas. These include leishmaniasis, malaria, and Crimea-Congo and other viral hemorrhagic fevers in Central Asia and Africa, dengue fever in Asia and the Americas, Japanese encephalitis (JE) and chikungunya fever in Asia, and rickettsial and other tick-borne infections in the U.S., Africa and Asia.

Whole body vibration in cystic fibrosis--a pilot study

INTRODUCTION

In cystic fibrosis (CF), bone mass deficits as well as a lack of muscle mass and force have been described. The bone mass deficits are thought to be at least in part secondary to the reduced muscle mass. Whole body vibration has recently been suggested as an effective technique to increase muscle force and power. The aim of this pilot study was to evaluate the compliance and safety of a side-alternating, whole body vibration platform in patients with CF and to assess its effects on muscle force, muscle power, bone mass and lung function.

PATIENTS AND METHODS

Eleven adult CF patients participated in a six-months home-based training programme on a whole body vibration platform. Muscle force and power were assessed with three standard manoeuvres on a ground reaction force plate at regular intervals. Bone densitometry was performed at the spine, the radius and the tibia using quantitative computerized tomography.

RESULTS

Regular cardiovascular monitoring did not show any critical drop in oxygen saturation or blood pressure. Lung function remained relatively constant with a median FEV1 change [% of norm] of -3.1% (range -7-20). Trabecular density at the spine and parameters of bone density and geometry at the radius and tibia did not show consistent changes. A median decrease of -0.3% (-31.0-17.9) for muscle force and a median increase of 4.7% (-16.4-74.5) for muscle power and 6.6% (-0.9-48.3) for velocity was noted in the two-leg jump. In the one-leg jump, a median increase of 6.7% (-8.5-24.3) for muscle force was measured.

CONCLUSIONS

Whole body vibration was well tolerated in the majority of the study participants. Most patients were able to increase peak force in the one-leg jump. In the two-leg jump, velocity and muscle power increased with equal or decreased muscle force. This may indicate an improvement in neuromuscular and intramuscular co-ordination (and therefore efficiency) with less muscle force necessary to generate the same power.

Diagnostik und Therapie der Rachitis

Rickets is caused by deficient mineralization at the level of growth plate and is usually due to a decreased serum calcium/phosphate product. Although the diagnosis of rickets can usually be suspected on the basis of a clinical examination (bone deformities in legs, impaired growth), radiological examination and detailed biochemical work-up are necessary to elucidate the etiology of the underlying disease. It is important to differentiate between calcipenic/vitamin deficient and phosphopenic rickets. The former is due to vitamin D deficiency, and the ultimate cause of this usually lies in altered vitamin D supply; however, impaired synthesis of or resistance to the actions of vitamin D can also be a cause. Phosphopenic rickets is usually related to impaired phosphate reabsorption in the proximal renal tubule. Both calcipenic and phosphopenic rickets can be acquired or hereditary in origin.

The use of L-T4 as liquid solution improves the practicability and individualized dosage in newborns and infants with congenital hypothyroidism

Dosage recommendations for the initial therapy of congenital hypothyroidism (CH) in newborns vary between 8 microg/kg/d and 10-15 microg/kg/d.

AIM

To evaluate the practicability of LT4 in liquid form and to define the initial dosage for optimal treatment.

METHODS

Liquid LT4 solution was administered to 28 consecutive newborns with primary CH. We measured TSH, T3, T4, free T3 and free T4 before therapy and during follow-up up to 2 years. After 2 years a standardized developmental test (Griffith) was performed.

RESULTS

The median dosage at start of therapy was 12.3 microg LT4/kg/d and decreased to about 5 microg LT4/kg/d after 9 months. The median time of normalization of TSH (< or =6 mU/l) was 2 weeks. In 21 patients, who received a median starting dosage of 12.7 microg LT4/kg (range 9.8-17.1 microg/kg), TSH levels normalized within a median of 1 week. Seven patients receiving only 10.1 microg LT4/kg normalized their TSH only after a median of 2 months.

CONCLUSIONS

Newborns with CH should normalize their TSH within 1-2 weeks. The initial dose necessary to normalize TSH is not lower when a liquid solution is used. The higher dose used in tablets is not due to inefficient absorption, but rather reflects the increased demand for thyroid hormone in the first weeks of life.

Decreased expression of IGF-II and its binding protein, IGF-binding protein-2, in genital skin fibroblasts of patients with complete androgen insensitivity syndrome compared with normally virilized males

The action of androgen by way of the AR is required for the development of male gonads and external genitalia. The interplay between androgens and the somatotropic axis, in particular the IGFs in sexual development, is currently under thorough investigation. The IGF system is thought to mediate the androgen action in androgen-responsive cells. To investigate the interaction of androgens with the IGF system, we compared the expression of IGFs and IGF-binding proteins in cultured genital skin fibroblasts from nine patients with the syndrome of complete androgen insensitivity with that in genital skin fibroblasts from 10 normally virilized males. Mutations in the AR gene and/or abnormalities of the AR protein in the immunoblot were detected in all complete androgen insensitivity genital skin fibroblast strains. They caused a complete failure of DHT binding. RIA and RT-PCR demonstrated that the genital skin fibroblast strains expressed IGF-II, IGF-binding protein-2, and IGF-binding protein-3, but no IGF-I. Most strikingly, complete androgen insensitivity genital skin fibroblast strains produced significantly lower IGF-II (P < 0.001; 42.2 +/- 9.7 vs. 106.9 +/- 11.8 ng/mg protein) and IGF-II mRNA (P < 0.01, by RT-PCR) than control genital skin fibroblast strains. The production of IGF-binding protein-2 was also decreased (P < 0.03) in complete androgen insensitivity genital skin fibroblasts, whereas that of IGF-binding protein-3 did not differ. Furthermore, high levels of IGF-binding protein-5 mRNA were detected in all genital skin fibroblast strains, whereby the 28-kDa band in the ligand blot, probably representing IGF-binding protein-5, was more abundant in complete androgen insensitivity genital skin fibroblasts. Exposure of the genital skin fibroblasts to T (5 x 10(-8) M) had only weak effects on the expression of IGFs and IGF-binding proteins. In conclusion, although the mechanism underlying these differences requires further study, it is conceivable that in addition to the endocrine actions of IGF-I, IGF-II and IGF-binding protein-2, as local growth factors, are involved in the mediation of androgen action and growth of genital tissues.

Short stature homeobox-containing gene deletion screening by fluorescence in situ hybridisation in patients with short stature

The short stature homeobox-containing gene (SHOX) on the short arm of the X and Y chromosomes is an important determining factor of stature phenotype. Absence of the SHOX gene is a main cause for short stature in patients with Turner syndrome. Mutations of the SHOX gene can also be responsible for Léri-Weill syndrome (dyschondrosteosis). The aim of this study was to determine the frequency of SHOX deletions in short stature children and to delineate indications for SHOX deletion screening. Out of 50 probands, 35 had idiopathic short stature, 12 cases showed additional anomalies of the forearms (in particular Madelung deformity) and three patients were affected by a congenital heart defect. Chromosomal investigations with fluoresence in situ hybridisation did not reveal a SHOX deletion in any patient with idiopathic short stature. In five of the 12 patients (41.7%) with anomalies of the forearms, a SHOX deletion on one sex chromosome could be detected. No deletion was observed in the three cases with additional heart defects.

CONCLUSION

The frequency of short stature homeobox-containing gene deletions in patients with idiopathic short stature appears to be very low and does not require a fluorescence in situ hybridisation analysis. Short stature in association with anomalies of the forearms such as Madelung deformity makes a deletion more probable and therefore screening for such deletions is recommended in these cases.

Molecular pathogenesis of neonatal hypothyroidism

In patients with congenital hypothyroidism (CH), the autosomal recessive inheritance of mutations of thyroid peroxidase, thyroglobulin and the NIS and pendrin genes encoding for sodium iodide transporters has been identified. CH due to thyroid dysgenesis was considered to be a sporadic disease, but recently, inheritable defects of thyroid development have been described. The autosomal recessive inheritance of mutations of the thyroid-stimulating hormone receptor gene was recognized in patients with CH and thyroid hypoplasia, while autosomal dominant mutations of the Pax-8 gene were described in patients with thyroid dysgenesis. In addition, analysis of mutations of the beta-thyrotropin gene has resulted in a new understanding of the pathogenesis of central CH. Molecular genetic studies in patients with CH detected by newborn screening will provide the information necessary for genetic counselling and may help to explain the less favourable outcome present in 5-10% of the patients.

How a patient homozygous for a 30-kb deletion of the C4-CYP 21 genomic region can have a nonclassic form of 21-hydroxylase deficiency

A case of nonclassic (NC) 21-hydroxylase deficiency, with a moderately elevated 17-hydroxyprogesterone level (145 nmol/L in filter paper blood spot), was detected in newborn screening. The newborn's phenotype was female, with no sign of virilization. Confirmatory diagnosis revealed elevated serum levels of 17-hydroxyprogesterone and of 21-desoxycortisol, whereas cortisol, PRA, and electrolytes were normal. Hydrocortisone substitution was considered at the age of 6 months, when virilization became obvious. For clinical reasons, this case had to be classified as late-onset congenital adrenal hyperplasia (CAH) with unusually early manifestation. However, the diagnosis of classic 21-hydroxylase deficiency was obtained by Southern blotting studies, showing that she was homozygous for the 30-kb deletion, including the 3' end of CYP21P pseudogene, the C4B gene, and the 5' end of the functional CYP21 gene. Further studies, using PCR and sequencing, were conducted to explain the discrepancy between this genotype, usually associated with a classic salt-wasting form, and the girl's phenotype. Typically, patients homozygous for the 30-kb deletion encoding classic CAH possess a unique CYP21P/21 hybrid gene with the junction site located after the third exon, yielding a nonfunctional pseudogene. The girl in question, however, was heterozygous for the 8-bp deletion, suggesting that the chimeric pseudogene on one allele had a junction site before the third exon. She was compound heterozygous for a 30-kb deletion encoding classic CAH on the paternal allele, and a 30-kb deletion encoding NC CAH on the maternal allele. This novel maternal CYP21P/21 hybrid gene is characterized by a junction site before intron 2 and differs from the normal CYP21 gene only by the P30L mutation in exon 1 and the promoter region of the CYP21P pseudogene. Because the P30L mutation has been described to result in an enzyme with 30-60% activity of the normal P450c21 enzyme, and the CYP21P promoter reduced the transcription to 20% of normal, this puzzling phenotype of a NC CAH with early onset may be fully explained by the genotype of the patient and considered as an intermediate form between the simple virilizing and NC form.

Mutations in LHX3 result in a new syndrome revealed by combined pituitary hormone deficiency

Combined pituitary hormone deficiency (CPHD) has been linked with rare abnormalities in genes encoding transcription factors necessary for pituitary development. We have isolated LHX3, a gene involved in a new syndrome, using a candidate-gene approach developed on the basis of documented pituitary abnormalities of a recessive lethal mutation in mice generated by targeted disruption of Lhx3 (ref. 2). LHX3, encoding a member of the LIM class of homeodomain proteins, consists of at least six exons located at 9q34. We identified a homozygous LHX3 defect in patients of two unrelated consanguineous families displaying a complete deficit in all but one (adrenocorticotropin) anterior pituitary hormone and a rigid cervical spine leading to limited head rotation. Two of these patients also displayed a severe pituitary hypoplasia, whereas one patient presented secondarily with an enlarged anterior pituitary. These LHX3 mutations consist of a missense mutation (Y116C) in the LIM2 domain at a phylogenetically conserved residue and an intragenic deletion predicting a severely truncated protein lacking the entire homeodomain. These data are consistent with function of LHX3 in the proper development of all anterior pituitary cell types, except corticotropes, and extrapituitary structures.

Free and protein bound leptin are distinct and independently controlled factors in energy regulation

AIMS/HYPOTHESIS

Leptin exerts important regulating effects on energy homeostasis and could have a central role in our understanding of obesity, diabetes mellitus and the metabolic syndrome. Leptin circulates in a free and protein bound form. The aim of the present study was to test whether both fractions of the leptin system can be selectively regulated and thus serve independent physiological roles.

METHODS

Using specific radioimmunoassays we measured both leptin components in relation to BMI in healthy subjects before and after weight reduction and in hyperthyroid patients during correction of thyrotoxicosis. In the latter group body composition and resting energy expenditure was monitored. In addition, we measured serum and cerebrospinal fluid concentrations of free and bound leptin in patients with neurological disorders.

RESULTS

Under all conditions free leptin concentrations reflected body fat mass. Bound leptin concentrations decreased during weight reduction but also after treatment of hyperthyroidism despite an increase in fat mass. Direct measurement of resting energy expenditure and bound leptin in hyperthyroid patients and under thyrostatic treatment showed a significant positive correlation of both variables. In contrast to free leptin whose transport into the cerebrospinal fluid appears to be saturated at low physiological concentrations of serum free leptin, bound leptin concentrations in the cerebrospinal fluid increased in parallel to serum concentrations over the whole physiologically relevant range.

CONCLUSION/INTERPRETATION

Our data indicate a distinct role of free and bound leptin in the feedback regulating energy intake and expenditure and could have important implications for our understanding of the physiology and pathophysiology of leptin-dependent signalling.

Complete androgen insensitivity caused by a new frameshift deletion of two base pairs in exon 1 of the human androgen receptor gene

We describe a novel mutation in exon 1 of the androgen receptor gene in a patient with complete androgen insensitivity (CAIS). Endocrine findings were typical for androgen insensitivity (testosterone serum levels in the upper limit of normal males and increased LH serum concentrations). Biochemical investigations in cultured genital skin fibroblasts of the patient showed a normal 5alpha-reductase activity but a complete absence of androgen binding. Western blot analysis revealed no detectable protein product. Sequence analysis of the entire coding region of the androgen receptor gene resulted in the identification of a 2-bp deletion in codon 472, causing frameshift and introduction of a premature stop codon 27 codons downstream of the mutation.

Functional activity of CD44 isoforms in haemopoiesis of the rat

Expression of CD44 is involved in the maturation as well as the homing of haemopoietic progenitor cells. Whether these processes are mediated by CD44 standard (CD44s) or variant (CD44v) isoforms is unknown. To assign functional activities of CD44 in haemopoiesis of the rat to distinct isoforms, ligand binding of haemopoietic progenitor cells was inhibited by monoclonal antibodies recognizing an epitope on CD44s (Ox50) or CD44 exon v6, (1.1ASML). The vast majority of rat bone marrow cells (BMC) as well as stromal cells and non-adherent cells in long-term bone marrown culture (LTBMC) expressed CD44s. Bone marrow cells and non-adherent cells in LTBMC, but not the stromal cells, also contained a population of large and granulated cells, which stained with anti-CD44v6. In vivo and in vitro reconstitution experiments revealed that homing of BMC as well as settlement on stromal elements was influenced exclusively by anti-CD44s, which also inhibited proliferation of progenitor cells. Anti-CD44v6 had no influence on homing and seeding, but interfered with stroma formation and progenitor maturation. Finally, restoration of functional activity of T-lineage cells was impaired in the presence of anti-CD44v6. The data indicate that CD44s and CD44v6 fulfilled distinct functions in haemopoiesis of the rat. Although CD44s facilitated homing and expansion of stem cells, progenitor cells, CD44v6 was involved in differentiation processes, particularly of lymphoid progenitor cells.

Molecular cloning and characterization of a full-length complementary DNA encoding human acid ceramidase. Identification Of the first molecular lesion causing Farber disease

Human acid ceramidase ((AC) N-acylsphingosine amidohydrolase, EC 3.5. 1.23) hydrolyzes the sphingolipid ceramide into sphingosine and free fatty acid. Ceramide is an essential component of all sphingolipids and an important cell-signaling molecule. Moreover, an inherited deficiency of AC activity leads to the lysosomal storage disorder known as Farber disease. Human AC was purified from urine, and 117 amino acid residues were determined by microsequencing. Degenerative oligonucleotide probes were then constructed and used to screen for human fibroblast and pituitary cDNA libraries. Several partial cDNA clones were obtained, and two of these were combined to construct a full-length cDNA containing a 17-base pair (bp) 5'-untranslated sequence, a 1185-bp open reading frame encoding 395 amino acids, a 1110-bp 3'-untranslated sequence, and an 18-bp poly(A) tail. Transient expression of the full-length cDNA in COS-1 cells led to a 10-fold increase in AC activity. In addition, biosynthetic studies carried out in the transfected cells demonstrated that 13-kDa (alpha) and 40-kDa (beta) AC subunits were derived from a common 55-kDa precursor encoded by the full-length cDNA. This protein pattern was identical to that seen in normal human skin fibroblasts. A homoallelic point mutation (T222K) was also identified in the AC gene of a patient suffering from Farber disease, further confirming the authenticity of the full-length cDNA.

Phenotypic classification of male pseudohermaphroditism due to steroid 5 alpha-reductase 2 deficiency

Conversion of testosterone (T) to dihydrotestosterone (DHT) in genital tissue is catalysed by the enzyme 5 alpha-reductase 2, which is encoded by the SRD5A2 gene. The potent androgen DHT is required for full masculinization of the external genitalia. Mutations of the SRD5A2 gene inhibit enzyme activity, diminish DHT formation, and hence cause masculinization defects of varying degree. The classical syndrome, formerly described as pseudovaginal perineoscrotal hypospadias, is characterized by a predominantly female phenotype at birth and significant virilization without gynecomastia at puberty. We investigated nine patients with steroid 5 alpha-reductase 2 deficiency (SRD). Phenotypes, which were classified according to the severity of the masculinization defect, varied between completely female (SRD type 5), predominantly female (SRD type 4), ambiguous (SRD type 3), predominantly male with micropenis and hypospadias (SRD type 2), and completely male without overt signs of undermasculinization (SRD type 1). T/DHT-ratios were highly increased ( > 50) in the classical syndrome (SRD type 5), but variable in the less severe affected patients (SRD types 1-4) (14-35). Mutations in the SRD5A2 gene had been characterized using PCR-SSCP analysis and direct DNA sequencing. A small deletion was encountered in two patients, while all other patients had single base mutations which result in amino acid substitutions. We conclude that phenotypes may vary widely in patients with SRD5A2 gene mutations spanning the whole range from completely female to normal male without distinctive clinical signs of the disease. Hence, steroid 5 alpha-reductase deficiency should be considered not only in sex reversed patients with female or ambiguous phenotypes, but also in those with mild symptoms of undermasculinization as encountered in patients with hypospadias and/or micropenis. A classification based on the severity of the masculinization defect may be used for correlation of phenotypes with enzyme activities and genotypes, and for comparisons of phenotypes between different patients as the basis for clinical decisions to be made in patients with pseudohermaphroditism due to steroid 5 alpha-reductase 2 deficiency.

Transient congenital hypothyroidism and hyperthyrotropinemia: normal thyroid function and physical development at the ages of 6-14 years

Since the introduction of screening programs for congenital hypothyroidism, transient disturbances of thyroid function, especially transient congenital hypothyroidism and hyperthyrotropinemia, mostly due to iodine deficiency or contamination have been observed with variable frequencies. This study was carried out to reevaluate the thyroid function and physical development of 61 schoolchildren with transient congenital hypothyroidism or transient congenital hyperthyrotropinemia. Abnormalities were observed in 3 children. Thyroid function and growth were normal in all children, except 2 with moderately elevated TSH levels at the age of 7.7 and 10 yr in the presence of normal thyroid hormone levels. In 1 child, the TSH elevation was due to an ectopic hemithyroidea; in the other child, an unknown familial cause was suggested. In 1 girl (aged 12 yr), a euthyroid goiter caused by autoimmune thyroiditis was detected. We conclude from our investigation that frequent monitoring of thyroid function in children with transient congenital hypothyroidism or transient congenital hyperthyrotropinemia is not necessary during childhood if, postnatally, thyroid function recovered spontaneously. However, the growth and development of children with neonatal thyroid dysfunction should be followed, and if abnormalities occur, thyroid function tests are essential.

Urinary excretion of galactosyl-hydroxylysine is a marker of growth in children

Galactosyl-hydroxylysine (Gal-Hyl) is the predominant product of the posttranslational glycosylation of skeletal collagen. Urinary Gal-Hyl excretion is regarded as a marker of bone resorption in adults, but little information is available on the validity of this parameter in pediatric age groups. Using 24-h urine samples from 88 healthy children and adolescents ages 4-18 yr, reference ranges were established for this age group, and values were compared with measurements in children with overt GH deficiency (n = 14) or Ullrich-Turner syndrome (n = 21). When expressed relative to body weight (Gal-Hyl/wt), urinary Gal-Hyl excretion was 3.2 to 4.7 times higher in subjects 4-16 yr of age than in adults. Highest values were observed in very young children and during the pubertal growth spurt. In the total population, urinary Gal-Hyl/wt was closely related to growth velocity (r = 0.72) and significantly correlated with the urinary excretion of both hydroxyproline (r = 0.74) and deoxypyridinoline (r = 0.88; P < 0.001 each). Urinary Gal-Hyl/wt was significantly lower in children with GH deficiency or Ullrich-Turner syndrome than in healthy children (P < 0.001 each). The urinary excretion of Gal-Hyl was significantly correlated with growth velocity in GH-deficient children (r = 0.69; P = 0.004) but not in patients with Ullrich-Turner syndrome. In the latter, the increase in urinary Gal-Hyl excretion after 3 months of treatment with recombinant human GH correlated significantly with the increase in growth velocity after 12 months of treatment (r = 0.76; P = 0.002). We conclude that the urinary excretion of Gal-Hyl is a valid and potentially useful index of skeletal growth in children.

Molecular genetics of GM2-gangliosidosis AB variant: a novel mutation and expression in BHK cells

The GM2 activator is a hexosaminidase A-specific glycolipid-binding protein required for the lysosomal degradation of ganglioside GM2. Genetic deficiency of GM2 activator leads to a neurological disorder, an atypical form of Tay-Sachs disease (GM2 gangliosidosis variant AB). Here, we describe a G506 to C transversion (Arg169 to Pro) in the mRNA of an infantile patient suffering from GM2-gangliosidosis variant AB. Using the polymerase chain reaction amplification and direct-sequencing technique, we found the patient to be homozygous for the mutation, whereas the parents were, as expected, heterozygous. BHK cells transfected with a construct of mutant cDNA gave no GM2 activator protein detectable by the Western blotting technique, whereas those transfected by a wild-type cDNA construct showed a significant level of human GM2 activator protein. The substitution of proline for the normal Arg169 therefore appears to result in premature degradation of the mutant GM2 activator, either during the post-translational processing steps or after reaching the lysosome. The basis for the phenotype of GM2 gangliosidosis variant AB may therefore be either inactivation of the physiological activator function by the point mutation or instability of the mutant protein.

Simultaneous deficiency of sphingolipid activator proteins 1 and 2 is caused by a mutation in the initiation codon of their common gene

Sphingolipid activator proteins (SAPs) are small, nonenzymic glycoproteins that stimulate lysosomal degradation of various sphingolipids. SAP-1, SAP-2, and two additional potential activator proteins are derived from a common precursor by proteolytic processing. A severe case of sphingolipid storage disease that led to death within 16 weeks was attributed to a possible total deficiency of the SAPs generated by this gene (Harzer, K., Paton, B. C., Poulos, A., Kustermann-Kuhn, B., Roggendorf, W., Grisar, T., and Popp, M. (1989) Eur. J. Pediatr. 149, 31-39). Analysis of the SAP precursor cDNA from the patient and his fetal sibling showed an A to T transversion in the initiation codon. Allele-specific oligonucleotide hybridization revealed that both parents are heterozygous carriers for this mutation. In pulse-chase experiments using antisera raised against SAP-1 or SAP-2, no cross-reacting material could be detected in the patients' fibroblasts.

A mutation in the gene of a glycolipid-binding protein (GM2 activator) that causes GM2-gangliosidosis variant AB

GM2-gangliosidoses are neurological disorders caused by a genetic deficiency of either the beta-hexosaminidase A or the GM2 activator, a glycolipid binding protein. In a patient with an immunologically proven GM2 activator protein deficiency, A T412----C transition (counted from A of the initiation codon) was found in the coding sequence, which results in the substitution of Arg for the normal Cys107 in the mature GM2 activator protein. The remainder of the coding sequence remained entirely normal.

Characterization of full-length cDNAs and the gene coding for the human GM2 activator protein

Full-length cDNAs coding for the human GM2-activator protein has been isolated and characterized, and its genomic structure studied in two overlapping clones in lambda-EMBL-4 isolated from a human brain genomic library. Two different cDNAs were found that were identical to the 5'-terminus to nt 1311 (counted from the A of the initiation codon, ATG) including the entire protein coding sequence. However, they were entirely dissimilar in the 3'-non-coding sequences. The genomic clones covered 94% of the full-length cDNA sequence. Three introns were found. The last exon spans contiguously the carboxyl terminus of the protein and the entire 3'-untranslated region of one of the two cDNAs with different 3'-ends. The origin of the 3'-portion of the other cDNA clone is not clear at this time.

Individualization of theophylline dosage: a Bayesian method evaluated in patients with once-daily dosing

A Bayesian drug dosing program was prospectively evaluated in 16 hospitalized patients with obstructive respiratory disease treated with a novel sustained-release preparation Euphylong. Theophylline was given as a single evening dose. By means of the Bayesian method, the early morning peak was predicted from a steady-state theophylline serum level determined at 8:00 a.m. The prediction errors were in all cases within a clinically acceptable range (mean prediction error +/- standard deviation: -0.2 +/- 1.3 mg/L). The results were compared with predictions based on steady state theophylline serum levels at 8:00 p.m. The prediction errors observed were on average greater than the prediction errors based on the serum levels at 8:00 a.m. (-0.6 +/- 2.5 mg/L). These findings suggest that the Bayesian method is useful for dosage predictions in patients treated once a day with Euphylong.

Mutation in the sphingolipid activator protein 2 in a patient with a variant of Gaucher disease

The lysosomal degradation of glucosylceramide requires the hydrolase, glucosylceramide-beta-glucosidase and a sphingolipid activator protein (Gaucher factor, SAP-2, saposin C). Genetic defects in either of these lysosomal proteins cause phenotypically similar disorders in man, the Gaucher disease. SAP-2 originates from a gene which generates a mRNA that codes for four homologous proteins. In a patient with an immunologically proven SAP-2 deficiency a G1154----T transversion (counted from A of the initiation codon ATG) was found in the mRNA of the SAP-2 precursor which results in the substitution of Phe for Cys385 in the mature SAP-2. The rest of the coding sequence remained entirely normal.

The organization of the gene for the human cerebroside sulfate activator protein

The organization of 14 exons covering 97% of the cDNA sequence of human cerebroside sulfate activator protein precursor has been determined from two overlapping EMBL-4 human genomic clones extending over 17 kb. All exons and exon/intron splice junctions and five introns were sequenced. Exon 8 consists of only 9 bp and is involved in alternative splicing which generates three different mRNAs of cerebroside sulfate activator precursor.

[Dose titration with Euphylong following prior determination of serum concentration in the steady state]

Euphylong is a theophylline preparation with new galenic slow-release design (micropellets in a capsule), developed for daily single-dose administration in the evening. It has been shown that the majority of patients with bronchial asthma, chronic obstructive bronchitis or emphysema who receive a single evening dose of Euphylong have a theophylline serum concentration that remains within the therapeutic range for 24 hours when the theophylline serum concentration measured at 8 a.m. under steady-state conditions is found to lie within the therapeutic range.

[Treatment of nocturnal bronchial asthma]

To date, the pathogenesis of nocturnal bronchiale asthma has not been completely clarified. For the treatment of nocturnal asthma that fails to respond to beta-2-sympathomimetics or inhalative glucocorticosteroids, theophylline in a delayed release form or delayed-release oral beta-2-sympathomimetics are available. In a double-blind crossover study, 10 patients with nocturnal or early-morning bronchial asthma were treated for one week with theophylline 390-900 mg daily (1/3 of the total dose being given in the morning, 2/3 in the evening) and one week with terbutaline 15 mg daily (7.5 mg in the morning and 7.5 mg in the evening). No significant differences were observed with respect to the measured peak flow values in the night and early morning. However, those receiving terbutaline more frequently required the additional application of inhalative beta-2-sympathomimetics for respiratory distress. Thus, the sustained-release form of theophylline is the more suitable drug for the treatment of nocturnal bronchial asthma. As a further study revealed, the sole administration of a sustained-release form of theophylline in the evening suffices. In the future, apart from theophylline in a delayed-release form, inhalative beta-2-sympathomimetics with a long-term effect will play an important role in the treatment of nocturnal breathing disorders.

Effect of recombinant human growth hormone on urinary 15N-nitrogen balance in girls with Turner syndrome as compared to children with growth hormone deficiency

15N-nitrogen balances before and on human growth hormone (hGH) were studied in 13 girls with Turner syndrome (TS) aged 4.4-16 (median 13.2) years (45,X0 or equivalent, no X0/XX mosaicism, no estrogen replacement). The results were compared with those reported from 9 patients with growth hormone deficiency (GHD). The TS patients received subcutaneous hGH doses of 2 x 3 (group A, n = 6), 3 x 2 (group B, n = 3), or 2 x 6 (group C, n = 4) IU/m2 on consecutive days. The mean 15N dose given to the patients of groups A and C was higher (13.6 mg/kg) than that given to those of group B (2.7 mg/kg). The lower hGH doses in the first two groups induced small positive mean 15N balance changes (+0.6 +/- 0.6 mg/kg 15N, group A; +0.03 mg/kg, group B). The higher hGH dose in group C caused a more marked mean balance change (+3.0 mg/kg 15N) comparable to that in GHD patients (+3.2 mg/kg). Individual variation of response, however, was larger in patients with TS than in those with GHD. With low and high hGH doses, there were responders and nonresponders. It is concluded from this pilot study in a small number of cases that 15N balance studies might be potentially useful to choose the appropriate hGH dose for long-term treatment in TS patients.