Roland Pfäffle

Age-specific stabilization in obesity prevalence in German children: A cross-sectional study from 1999 to 2008

OBJECTIVEnTrends of overweight (ov)/obesity (ob) prevalence among German children aged 4-16 years were studied between 1999 and 2008.nnnSUBJECTSnBody mass index (BMI) data (>P90 [ov] and >P97 [ob]) from the national CrescNet database were analysed in three age groups: 4-7.99, 8-11.99, and 12-16 years.nnnRESULTSnTrend analyses. Data from 272 826 children were analyzed. a) Whole study population aged 4-16 years old. A significant upward trend for ov/ob prevalence was found between 1999 and 2003, and a significant downward trend between 2004 and 2008. b) Subgroup analyses. Ov/Ob prevalence increased in most subgroups studied until 2004. Between 2004 and 2008, a downward trend for ov/ob prevalence was found in children, aged 4-7.99 years, whereas it stabilized in most other subgroups studied. Cross-sectional analyses. Data from 93 028 children were analyzed. Ov/ob prevalence was significantly higher in 2004 compared with 2000 in girls aged 12-16 years and in boys aged 8-16 years. Ov/ob obesity prevalence was significantly lower in 2008 compared with 2004 in children aged 4-7.99 years.nnnCONCLUSIONnOv/ob prevalence increased between 1999 and 2003 in German children. Since 2004, this trend has been stabilizing or turning into a downward trend. Our data confirm the global trend of stabilizing prevalence rates of childhood obesity at a high level and add important information for individual age groups. Intervention programs targeted to prevent childhood obesity may have had beneficial effects, and a new balance between factors favouring obesity and those favouring leanness may have been reached recently. Age- and gender-specific differences found in trends of ov/ob prevalence may help optimise preventive and therapeutic measures.

Pituitary transcription factors in the aetiology of combined pituitary hormone deficiency

The somatotropic axis is the central postnatal regulator of longitudinal growth. One of its major components--growth hormone--is produced by the anterior lobe of the pituitary, which also expresses and secretes five additional hormones (prolactin, thyroid stimulating hormone, follicle stimulating hormone, luteinizing hormone, adrenocorticotropic hormone). Proper development of the pituitary assures the regulation of critical processes such as metabolic control, puberty and reproduction, stress response and lactation. Ontogeny of the adenohypophysis is orchestrated by inputs from neighbouring tissues, cellular signalling molecules and transcription factors. Perturbation of expression or function of these factors has been implicated in the aetiology of combined pituitary hormone deficiency (CPHD). Mutations within the genes encoding for the transcription factors LHX3, LHX4, PROP1, and POU1F1 (PIT1) that act at different stages of pituitary development result in unique patterns of hormonal deficiencies reflecting their differential expression during organogenesis. In the case of LHX3 and LHX4 the phenotype may include extra-pituitary manifestations due to the function of these genes/proteins outside the pituitary gland. The remarkable variability in the clinical presentation of affected patients indicates the influence of the genetic background, environmental factors and possibly stochastic events. However, in the majority of CPHD cases the aetiology of this heterogeneous disease remains unexplained, which further suggests the involvement of additional genes. Identification of these factors might also help to close the gaps in our understanding of pituitary development, maintenance and function.

Roles of the LHX3 and LHX4 LIM-Homeodomain Factors in Pituitary Development

The LHX3 and LHX4 LIM-homeodomain transcription factors play essential roles in pituitary gland and nervous system development. Mutations in the genes encoding these regulatory proteins are associated with combined hormone deficiency diseases in humans and animal models. Patients with these diseases have complex syndromes involving short stature, and reproductive and metabolic disorders. Analyses of the features of these diseases and the biochemical properties of the LHX3 and LHX4 proteins will facilitate a better understanding of the molecular pathways that regulate the development of the specialized hormone-secreting cells of the mammalian anterior pituitary gland.

IGF signaling defects as causes of growth failure and IUGR

A substantial portion of children born small for gestational age (SGA) fail to catch up height, despite normal or even elevated insulin-like growth factor (IGF1) serum levels. In most cases, the etiology of the apparent IGF1 resistance is regarded as idiopathic. However, the recent identification of human IGF1 and IGF1 receptor (IGF1R) mutations, as well as information obtained from transgenic animals, points to a strong genetic component being of pivotal importance in the development of growth retardation. These findings direct attention to molecules downstream of the IGF1R, which have both growth-promoting and, to a lesser extent, metabolic functions. Therefore, defects in these molecules are likely to participate in the etiology of human SGA.

A Heterozygous Mutation of the Insulin-Like Growth Factor-I Receptor Causes Retention of the Nascent Protein in the Endoplasmic Reticulum and Results in Intrauterine and Postnatal Growth Retardation

BACKGROUNDnMutations in the IGF-I receptor (IGF1R) gene can be responsible for intrauterine and postnatal growth disorders.nnnOBJECTIVEnHere we report on a novel mutation in the IGF1R gene in a female patient. The aim of our study was to analyze the functional impact of this mutation.nnnPATIENTnAt birth, the girls length was 47 cm [-1.82 sd score (SDS)], and her weight was 2250 g (-2.26 SDS). Clinical examination revealed microcephaly and retarded cognitive development. She showed no postnatal catch-up growth but had relatively high IGF-I levels (+1.83 to +2.17 SDS).nnnRESULTSnDenaturing HPLC screening and direct DNA sequencing disclosed a heterozygous missense mutation resulting in an amino acid exchange from valine to glutamic acid at position 599 (V599E-IGF1R). Using various cell systems, we found that the V599E-IGF1R mutant was not tyrosine phosphorylated and had an impaired downstream signaling in the presence of IGF-I. Flow cytometry and live cell confocal laser scanning microscopy revealed a lack of cell surface expression due to an extensive retention of V599E-IGF1R proteins within the endoplasmic reticulum.nnnCONCLUSIONnThe V599E-IGF1R mutation interferes with the receptors trafficking path, thereby abrogating proreceptor processing and plasma membrane localization. Diminished cell surface receptor density solely expressed from the patients wild-type allele is supposed to lead to insufficient IGF-I signaling. We hypothesize that this mechanism results in intrauterine and postnatal growth retardation of the affected patient. The reported retention of the nascent IGF1R in the endoplasmic reticulum presents a novel mechanism of IGF-I resistance.

IGF1R mutations as cause of SGA.

Until 2003 monogenetic aberrations that lead to a child that is born too small for gestational age (SGA) were poorly defined. With the first report of mutations within the insulin-like growth factor type 1 receptor (IGF1R) gene in two non-syndromic patients born SGA, who failed to thrive despite normal or even elevated IGF1 serum concentrations the concept of IGF1 resistance has been established. The identification of additional individuals bearing IGF1R mutations along with comparative, genetic, structural and biochemical studies has provided evidence for the pathogenic impact of the IGF1R mutations on human longitudinal growth. However, the variability in the occurrence of additional clinical manifestations, such as developmental delay, might indicate that the pleiotropic functions of the IGF-IGF1R system are partially redundant. It is apparent that we have just begun to unravel the multifaceted IGF1R actions at the interface of growth control, maintenance of metabolic homeostasis and neurodevelopment and neural protection.

New N-terminal located mutation (Q4ter) within the POU1F1-gene (PIT-1) causes recessive combined pituitary hormone deficiency and variable phenotype.

OBJECTIVEnGrowth is an inherent property of life. About 10% of the congenital forms of growth retardation and short stature are genetically caused. Beside the gene involved in direct GH-production, there are different candidate genes important for appropriate pituitary development causing combined pituitary hormone deficiency (CPHD). However, severe growth retardation and failure to thrive remain the leading reason for medical assessment in these patients.nnnPATIENTS AND METHODSnWe report two siblings of a healthy but consanguineous Malaysian family presenting with severe short stature caused by CPHD with a variable phenotype. Importantly, at the beginning the girl presented with isolated GHD, whereas the boy was hypothyroid. As the most common gene alterations responsible for CPHD are within either the PROP-1- or the POU1F1- (PIT-1)-gene these two genes were further studied.nnnRESULTSnSubsequent sequencing of the six exons of the POU1F1-gene allowed the identification of a new N-terminal mutation (Q4ter) in these two children. A substitution of C to T induced a change from a glutamine (CAA) to a stop codon (TAA) in exon 1 of the PIT-1 protein. Both affected children were homozygous for the mutation, whereas the mother and father were heterozygous.nnnCONCLUSIONnWe describe two children with autosomal recessive inherited CPHD caused by a new N-terminal located mutation within the PUO1F1-gene. The clinical history of these two children underline the phenotypic variability and support the fact that children with any isolated and/or combined PHD need to be closely followed as at an any time other hormonal deficiencies may occur. In addition, molecular analysis of the possible genes involved might be most helpful for the future follow-up.

Compound Heterozygous and Homozygous Mutations of the TSHβ Gene as a Cause of Congenital Central Hypothyroidism in Europe

Background: Thyroid hormones are crucial for normal growth and central nervous system development. In recent years, germline variants of the TSHβ subunit gene have been identified as a cause of congenital TSH deficiency. Methods: We performed a genetic and clinical study in children from four European countries diagnosed with congenital isolated central hypothyroidism. Results: TSHβ gene analysis revealed compound heterozygosity for 145C→T (Q49X) and 313delT (C105Vfs114X) in 1 infant and homozygous mutation 313delT (C105Vfs114X) in 5 patients. Although all presented with typical symptoms of hypothyroidism, diagnosis and treatment was delayed until 3–5 months in 5 of 6 patients. In a longitudinal sibpair analysis, thyroxine substitution initiated immediately after birth was effective to prevent developmental delay and growth retardation. Conclusion: Clinical awareness is required to detect hypothyroidism due to TSHβ mutations, which is not identified by TSH-based newborn screening. TSHβ variants C105Vfs114X and Q49X are the most frequent cause of this severe disorder in Europe, now for the first time observed in compound heterozygous state.

Homozygous mutation of the IGF1 receptor gene in a patient with severe pre- and postnatal growth failure and congenital malformations

BACKGROUNDnHeterozygous mutations in the IGF1 receptor (IGF1R) gene lead to partial resistance to IGF1 and contribute to intrauterine growth retardation (IUGR) with postnatal growth failure. To date, homozygous mutations of this receptor have not been described.nnnSUBJECTnA 13.5-year-old girl born from healthy first-cousin parents presented with severe IUGR and persistent short stature. Mild intellectual impairment, dysmorphic features, acanthosis nigricans, and cardiac malformations were also present.nnnMETHODSnAuxological and endocrinological profiles were measured. All coding regions of the IGF1R gene including intron boundaries were amplified and directly sequenced. Functional characterization was performed by immunoblotting using patients fibroblasts.nnnRESULTSnIGF1 level was elevated at 950NG/ML (+7 S.D.). Fasting glucose level was normal associated with high insulin levels at baseline and during an oral glucose tolerance test. Fasting triglyceride levels were elevated. sequencing of the IGF1R gene led to the identification of a homozygous variation in exon 2: c.119G>T (p.Arg10Leu). As a consequence, IGF1-dependent receptor autophosphorylation and downstream signaling were reduced in patients fibroblasts. Both parents were heterozygous for the mutation.nnnCONCLUSIONnThe homozygous mutation of the IGF1R is associated with severe IUGR, dysmorphic features, and insulin resistance, while both parents were asymptomatic heterozygous carriers of the same mutation.

Functional Characterization of a Heterozygous GLI2 Missense Mutation in Patients With Multiple Pituitary Hormone Deficiency

CONTEXTnThe GLI2 transcription factor is a major effector protein of the sonic hedgehog pathway and suggested to play a key role in pituitary development. Genomic GLI2 aberrations that mainly result in truncated proteins have been reported to cause holoprosencephaly or holoprosencephaly-like features, sometimes associated with hypopituitarism.nnnOBJECTIVEnOur objective was to determine the frequency of GLI2 mutations in patients with multiple pituitary hormone deficiency (MPHD).nnnDESIGNnPatients were selected from participants in the Genetics and Neuroendocrinology of Short Stature International Study (GeNeSIS) program. Patients with mutations within established candidate genes were excluded.nnnPATIENTSnA total of 165 patients with MPHD defined as GH deficiency and at least 1 additional pituitary hormone deficiency were studied regardless of the presence of extrapituitary clinical manifestations.nnnMAIN OUTCOME MEASURESnPrevalence of GLI2 variations in MPHD patients was assessed and detailed phenotypic characterization is given. Transcriptional activity of identified GLI2 variants was evaluated by functional reporter assays.nnnRESULTSnIn 5 subjects, 4 heterozygous missense variants were identified, of which 2 are unpublished so far. One variant, p.R516P, results in vitro in a complete loss of protein function. In addition to GH deficiency, the carrier of the mutation demonstrates deficiency of thyrotrope and gonadotrope function, a maldescended posterior pituitary lobe, and polydactyly, but no midline defects.nnnCONCLUSIONSnFor the first time, we show that heterozygous amino acid substitutions within GLI2 may lead to MPHD with mild extrapituitary findings. The phenotype of GLI2 mutations is variable, and penetrance is incomplete. GLI2 mutations are associated with anterior pituitary hypoplasia, and frequently, ectopy of the posterior lobe occurs.