Extreme Growth Retardation Research Articles

Novel PCNT variants in MOPDII with attenuated growth restriction and pachygyria.

Biallelic loss‐of‐function mutations in the centrosomal pericentrin gene (PCNT) cause microcephalic osteodysplastic primordial dwarfism type II (MOPDII), which is characterized by extreme growth retardation, microcephaly, skeletal dysplasia, and dental anomalies. Life expectancy is reduced due to a high risk of cerebral vascular anomalies. Here, we report two siblings with MOPDII and attenuated growth restriction, and pachygyria. Compound heterozygosity for two novel truncated PCNT variants was identified. Both truncated PCNT proteins were expressed in patient's fibroblasts, with a reduced total protein amount compared to control. Patient's fibroblasts showed impaired cell cycle progression. As a novel finding, 20% of patient's fibroblasts were shown to express PCNT comparable to control. This was associated with normal mitotic morphology and normal co‐localization of mutated PCNT with centrosome‐associated proteins γ‐tubulin and centrin 3, suggesting some residual function of truncated PCNT proteins. These data expand the clinical and molecular spectrum of MOPDII and indicate that residual PCNT function might be associated with attenuated growth restriction in MOPDII.

Growth standard charts for Japanese children with mean and standard deviation (SD) values based on the year 2000 national survey.

Growth charts are essential and universally used for evaluating growth and development of children in both clinical settings and in public health examinations (1, 2). We previously reported the growth standards for Japanese children with percentile values based on the year 2000 national survey data (3), which were established by the lambda-mu-sigma (LMS) method (4). These standards have been widely used mainly in public health examinations. In clinical practices, Japanese physicians preferably assess growth with standard deviation (SD) scores, because many physicians feel that percentiles are not suitable for monitoring children with extreme growth retardation. Considering this, we created practical growth charts with mean and SD values, based on the criteria of the national medical aid program for specific pediatric chronic diseases by using the eye-fitting method (5). Although these charts have been widely used in clinical settings, they do not reflect the correct distributions of height and weight for Japanese children, especially the weight chart. Weight is not usually distributed normatively, but the practical weight chart was made with the assumption of a normal distribution. To this end, we saw the need for growth standards that can be used appropriately both for clinical and public health purposes. Therefore, we reanalyzed the previously reported growth standard charts with percentile values (3) and constructed the growth standards with mean and SD values for Japanese children, which would be applicable not only for clinical practices but also for public health examinations.

Extreme Growth Failure is a Common Presentation of Ligase IV Deficiency

Ligase IV syndrome is a rare differential diagnosis for Nijmegen breakage syndrome owing to a shared predisposition to lympho-reticular malignancies, significant microcephaly, and radiation hypersensitivity. Only 16 cases with mutations in LIG4 have been described to date with phenotypes varying from malignancy in developmentally normal individuals, to severe combined immunodeficiency and early mortality. Here, we report the identification of biallelic truncating LIG4 mutations in 11 patients with microcephalic primordial dwarfism presenting with restricted prenatal growth and extreme postnatal global growth failure (average OFC −10.1 s.d., height −5.1 s.d.). Subsequently, most patients developed thrombocytopenia and leucopenia later in childhood and many were found to have previously unrecognized immunodeficiency following molecular diagnosis. None have yet developed malignancy, though all patients tested had cellular radiosensitivity. A genotype–phenotype correlation was also noted with position of truncating mutations corresponding to disease severity. This work extends the phenotypic spectrum associated with LIG4 mutations, establishing that extreme growth retardation with microcephaly is a common presentation of bilallelic truncating mutations. Such growth failure is therefore sufficient to consider a diagnosis of LIG4 deficiency and early recognition of such cases is important as bone marrow failure, immunodeficiency, and sometimes malignancy are long term sequelae of this disorder.

Microcephalic osteodysplastic primordial dwarfism type I with biallelic mutations in the RNU4ATAC gene

Microcephalic osteodysplastic primordial dwarfism type I (MOPD I) is a rare autosomal recessive developmental disorder characterized by extreme intrauterine growth retardation, severe microcephaly, central nervous system abnormalities, dysmorphic facial features, skin abnormalities, skeletal changes, limb deformations, and early death. Recently, mutations in the RNU4ATAC gene, which encodes U4atac, a small nuclear RNA that is a crucial component of the minor spliceosome, were found to cause MOPD I. MOPD I is the first disease known to be associated with a defect in small nuclear RNAs. We describe here the clinical and molecular data for 17 cases of MOPD I, including 15 previously unreported cases, all carrying biallelic mutations in the RNU4ATAC gene.

Population Mutation Scanning of Human GHR by meltMADGE and Identification of a Paucimorphic Variant

Current studies of human genetic diversity are focused in two areas: first, detection of rare mutations in highly selected clinical cases; and second, in common single-nucleotide polymorphism (SNP) and haplotype effects in the general population. Less frequent SNPs and "paucimorphisms" remain underexplored, although lower frequency coding SNPs are more likely to have functional impact. We have developed a cost-efficient mutation scanning technology, meltMADGE, for population mutation scanning. Previous research in GHR has explored its role in extreme (-3 SD) growth retardation and, subsequently, "moderate" (-2 SD) growth retardation cases. Here, we describe meltMADGE assays for the entire coding region of GHR. As a first step we have established long polymerase chain reaction subbanks for GHR from 2423 unselected subjects and have applied meltMADGE scanning assays of exons 4 and 5 to these subbanks. A novel paucimorphism present at 439+30A>C (allele frequency: 0.0021) in intron 5 (location chr5:42,695,221 in GRCh37/hg19) was identified in 10 individuals, confirmed by sequencing and analysis made for major phenotypic effects. This approach is relevant to the deep sampling of populations for less frequent sequence diversity, some of which is expected to exert significant phenotypic effects.

Increased Wingless (Wnt) signaling in pituitary progenitor/stem cells gives rise to pituitary tumors in mice and humans.

Wingless (Wnt)/β-catenin signaling plays an essential role during normal development, is a critical regulator of stem cells, and has been associated with cancer in many tissues. Here we demonstrate that genetic expression of a degradation-resistant mutant form of β-catenin in early Rathke's pouch (RP) progenitors leads to pituitary hyperplasia and severe disruption of the pituitary-specific transcription factor 1-lineage differentiation resulting in extreme growth retardation and hypopituitarism. Mutant mice mostly die perinatally, but those that survive weaning develop lethal pituitary tumors, which closely resemble human adamantinomatous craniopharyngioma, an epithelial tumor associated with mutations in the human β-catenin gene. The tumorigenic effect of mutant β-catenin is observed only when expressed in undifferentiated RP progenitors, but tumors do not form when committed or differentiated cells are targeted to express this protein. Analysis of affected pituitaries indicates that expression of mutant β-catenin leads to a significant increase in the total numbers of pituitary progenitor/stem cells as well as in their proliferation potential. Our findings provide insights into the role of the Wnt pathway in normal pituitary development and demonstrate a causative role for mutated β-catenin in an undifferentiated RP progenitor in the genesis of murine and human craniopharyngioma.

PROTEIN malnutrition in South India.

A protein malnutrition survey was carried out in ten areas of four States of South India among children under 5 years of age in families with a monthly income of less than Rs 100, estimated to constitute 85% of the population. The agricultural situation and socio-economic conditions are described. The diets investigated consisted largely of cereals, with small quantities of pulses and green vegetables; milk, meat and eggs were little eaten. The survey covered investigation of infant care, feeding and weaning practices, clinical examinations, anthropometric measurements, determinations of haemoglobin and serum protein, and analysis of hospital records.Although infants were usually breast-fed for a long time, the quantity of breast milk was found to be low after 6 months, at which time supplementary foods were introduced, but these were usually inadequate. Extreme growth retardation was seen after weaning. Diarrhoea was complained of in some 20% of children. Such deficiency signs as dyschromotrichia, hepatomegaly, moon face, angular stomatitis and xerophthalmia were frequently seen. Frank cases of kwashiorkor and marasmus were observed in 1% and 1.7% respectively of children at home. These findings and others clearly show protein malnutrition to be a problem of very considerable magnitude in the poorer communities of South India. A comparison is made with the results of surveys conducted in Africa and in Central America.

How much is too much? Phenotypic consequences of Rai1 overexpression in mice

The retinoic acid induced 1 (RAI1) gene when deleted or mutated results in Smith-Magenis syndrome (SMS), while duplication of 17p11.2, including RAI1, results in the dup(17)(p11.2) syndrome characterized by mental retardation, growth and developmental delays, and hyperactivity. Mouse models for these human syndromes may help define critical roles for RAI1 in mammalian development and homeostasis that otherwise cannot be deduced from patient studies. A mouse model for duplication, Dp(11)17+, involving Rai1 has been reported. However, this mutant was engineered on a mixed genetic background confounding phenotypic effects due to possible modifier genes. We have therefore created and evaluated mice with a graded series of four (hemizygous) and six (homozygous) copies of Rai1, and overexpressing Rai1>1.5-fold and >2-fold, respectively. Data show that Rai1-transgenic mice have growth retardation, increased locomotor activity, and abnormal anxiety-related behavior compared to wild-type littermates. Rai1-transgenic mice also have an altered gait with short strides and long sways, impaired ability on a cage-top hang test, decreased forelimb grip strength, and a dominant social behavior. Further, analyses of homozygous transgenic mice revealed a dosage-dependent exacerbation of the phenotype, including extreme growth retardation, severe neurological deficits, and increased hyperactivity. Our results show that Rai1 dosage has major consequences on molecular processes involved in growth, development, and neurological and behavioral functions, thus providing evidence for several dosage-thresholds for phenotypic manifestations causing dup(17)(p11.2) syndrome or SMS in humans.

Metabolic programming during pregnancy: epidemiological studies in humans

Fetal growth and later diseaseEpidemiological evidence gathered over the past 15 yearshas shown that impaired fetal growth affects susceptibilityto cardiovascular disease and type II diabetes in adult life.Across a wide variety of populations, lower birth weight,and thinness at birth, is associated with an increased risk ofdevelopment of these conditions. These associations areevident within the normal range of birth weight, and are notexplained by effects of extreme growth retardation, bydifferences in gestational age at birth, or by differences inadult lifestyle [1].Interaction of fetal with postnatal experiencein influencing disease risk in adult lifeIn recent studies of individuals whose postnatal growth wasdescribed in detail, the effects of poor fetal growth on laterdisease have been shown to be compounded by continuedpoor growth in infancy, but followed by rapid weight gainin childhood. Amongst Finnish men and women, anincreased risk of coronary heart disease was seen in thosewho were thin at birth and in infancy, but who gainedweight rapidly after the age of 2 years [3].The influence of different pathways of growth on laterhealth has also been described in a study of young Indianadults [4]. The pattern of growth associated with impairedglucose tolerance or diabetes in adult life was characterisedby thinness between birth and the age of 2 years, but fol-lowed by rapid weight gain in childhood and a relativelyhigh body mass index at the age of 12 years.The significance of a single measure of BMI, or of beingoverweight, at any age, in relation to cardiovascular diseaseand impaired glucose tolerance, therefore differs accordingto earlier pathways of growth—and some individuals maybe more vulnerable to the effects of excess body weight asa result of their early experience.Vulnerability to stressors in adult lifeFollow-up of individuals who differ according to theirpathways of fetal and postnatal growth has provided evi-dence that responses, and therefore vulnerability, to theeffects of adverse influences in adult life are conditioned byearly growth. For example, in the American nurses’ healthstudy, the highest risk of coronary heart disease was foundamong women who had low birth weight but who had ahigh body mass index as adults [7].Among a group of Finnish men born between 1934–1944, low income was associated with increased rates ofcoronary heart disease as would be expected [2]. However,the association differed according to thinness at birth,defined by the ponderal index (birth weight/length

Body fat distribution and metabolic variables in patients with neonatal progeroid syndrome

Neonatal progeroid syndrome (NPS), also known as Wiedemann-Rautenstrauch Syndrome, is a rare autosomal recessive disorder characterized by accelerated aging and lipodystrophy from birth. Affected children have extreme intrauterine growth retardation, poor postnatal weight gain, and characteristic facial dysmorphic features such as a triangular shape, pinched nose, pseudohydrocephalus with wide fontanelles and prominent subcutaneous (sc) veins. Generalized loss of sc fat has been reported as a cardinal feature; however, the pattern of fat loss and its association with insulin resistance and its metabolic complications have not been systematically studied. The aim of the current study was to examine body fat distribution and body composition in two girls with NPS using anthropometric measures, whole-body magnetic resonance imaging (MRI) and dual energy X-ray absorptiometry (DEXA), and to assess metabolic complications such as hyperinsulinemia and dyslipidemia. Both the girls (aged 17 years and 10 years, respectively) had generalized paucity of sc fat on physical examination. However, measurements of skin-fold thickness revealed that sc fat was decreased over the extremities, but preserved over the chest and abdomen. MRI studies confirmed the presence of normal amounts of sc truncal fat, and marked loss of fat from the face and distal extremities. Striking fat loss was also noted in the paravertebral and lateral gluteal regions. Interestingly, body composition analysis with DEXA scan revealed a marked reduction in both the fat and lean tissue mass. Fasting glucose, lipids and insulin levels were not elevated. We conclude that patients with NPS do not have generalized lipodystrophy as previously reported, but fat loss is confined to the face, distal extremities, and possibly the paravertebral and lateral gluteal regions. Metabolic abnormalities related to insulin resistance are also uncommon in this condition.

Prenatal and pre-weaning growth and nutrition of cattle: long-term consequences for beef production

Severe, chronic growth retardation of cattle early in life reduces growth potential, resulting in smaller animals at any given age. Capacity for long-term compensatory growth diminishes as the age of onset of nutritional restriction resulting in prolonged growth retardation declines. Hence, more extreme intrauterine growth retardation can result in slower growth throughout postnatal life. However, within the limits of beef production systems, neither severely restricted growth in utero nor from birth to weaning influences efficiency of nutrient utilisation later in life. Retail yield from cattle severely restricted in growth during pregnancy or from birth to weaning is reduced compared with cattle well grown early in life, when compared at the same age later in life. However, retail yield and carcass composition of low- and high-birth-weight calves are similar at the same carcass weight. At equivalent carcass weights, cattle grown slowly from birth to weaning have carcasses of similar or leaner composition than those grown rapidly. However, if high energy, concentrate feed is provided following severe growth restriction from birth to weaning, then at equivalent weights post-weaning the slowly-grown, small weaners may be fatter than their well-grown counterparts. Restricted prenatal and pre-weaning nutrition and growth do not adversely affect measures of beef quality. Similarly, bovine myofibre characteristics are little affected in the long term by growth in utero or from birth to weaning. Interactions were not evident between prenatal and pre-weaning growth for subsequent growth, efficiency, carcass, yield and beef-quality characteristics, within our pasture-based production systems. Furthermore, interactions between genotype and nutrition early in life, studied using offspring of Piedmontese and Wagyu sired cattle, were not evident for any growth, efficiency, carcass, yield and beef-quality parameters. We propose that within pasture-based production systems for beef cattle, the plasticity of the carcass tissues, particularly of muscle, allows animals that are growth-retarded early in life to attain normal composition at equivalent weights in the long term, albeit at older ages. However, the quality of nutrition during recovery from early life growth retardation may be important in determining the subsequent composition of young, light-weight cattle relative to their heavier counterparts. Finally, it should be emphasised that long-term consequences of more specific and/or acute environmental influences during specific stages of embryonic, foetal and neonatal calf development remain to be determined. This need for further research extends to consequences of nutrition and growth early in life for reproductive capacity.

Extremely Growth-Retarded Infants: Is There a Viability Centile?

It is known that extremely premature infants do less well than more mature infants, and this fact has led some countries to adopt a "cutoff for viability" using birth weight or gestation. Infants affected by intrauterine growth retardation are at additional risk of poor outcome. There are few data to inform decisions about viability and (dis)continuation of intensive care when both extreme prematurity and severe growth retardation are present. We focused on (1) premature infants affected by marked intrauterine growth retardation to determine if there was a cutoff weight centile below which the mortality sharply increased and (2) the short-term outcome of extremely premature and growth-retarded infants to determine a cutoff for viability. We evaluated preterm infants of 22-32 weeks' gestation if they were alive at the onset of labor and born to European mothers resident in the Trent (United Kingdom) health region between 1994 and 2003. Infants were categorized into 6 weight centiles, and infants in each category were assessed for survival to discharge from the neonatal unit, duration of respiratory support, length of stay in the neonatal unit, and the age at death in nonsurvivors. We identified a total of 8228 infants who met the study criteria. Of these, 4448 infants were male, 6194 were from singleton pregnancies, and 2887 were born at < or = 28 completed weeks of gestation. Survival to discharge was markedly reduced in the infants born at < or = 28 weeks of gestation with a birth weight less than the 2nd centile. Stillbirth was inversely related to birth weight centile in infants born before 29 weeks of gestation. The survival for infants born at < or = 28 weeks' gestation and having a birth weight in less than the 2nd centile is poor, and consideration should be given to modifying their management.

Impaired Generation of Reactive Oxygen Species in Leprechaunism Through Downregulation of Nox4

Leprechaunism features a clinical constellation characterized by extreme insulin resistance, growth retardation, and several distinct developmental abnormalities. One puzzling observation about leprechaunism is that mutations in the insulin receptor gene frequently associated with this syndrome cannot account for the aberrant responses of cultured cells to other growth factors. Here we report that the generation of reactive oxygen species (ROS) is impaired in cells from leprechaunism patients, thus shedding new light on this issue. Stimulation of patients' skin fibroblast cells with platelet-derived growth factor (PDGF) resulted in a lower-level tyrosine phosphorylation of cytosolic proteins compared with that seen in normal cells. In addition, consistent with the hypothesis that ROS mediate the level of tyrosine phosphorylation of cytosolic proteins through inactivation of protein tyrosine phosphatases (PTPases), patient fibroblast cells showed a significantly higher phosphatase activity than normal cells. We further showed that the lower-level tyrosine phosphorylation in response to growth factors results from the downregulation of an NADPH oxidase, Nox4, which in turn results in the reduction of ROS generation. Ectopic expression of Nox4 in the patient fibroblast cells consistently restored PDGF-induced ROS production and regulation of PTPase activities. Taken together, these data provide insight into the mechanisms through which growth retardation is associated with leprechaunism syndrome.

Mosaic analysis of insulin receptor function.

Insulin promotes both metabolism and growth. However, it is unclear whether insulin-dependent growth is merely a result of its metabolic actions. Targeted ablation of insulin receptor (Insr) has not clarified this issue, because of early postnatal lethality. To examine this question, we generated mice with variable cellular mosaicism for null Insr alleles. Insr ablation in approximately 80% of cells caused extreme growth retardation, lipoatrophy, and hypoglycemia, a clinical constellation that resembles the human syndrome of leprechaunism. Insr ablation in 98% of cells, while resulting in similar growth retardation and lipoatrophy, caused diabetes without beta-cell hyperplasia. The growth retardation was associated with a greater than 60-fold increase in the expression of hepatic insulin-like growth factor binding protein-1. These findings indicate that insulin regulates growth independently of metabolism and that the number of insulin receptors is an important determinant of the specificity of insulin action.

Mosaic analysis of insulin receptor function

Insulin promotes both metabolism and growth. However, it is unclear whether insulin-dependent growth is merely a result of its metabolic actions. Targeted ablation of insulin receptor (Insr) has not clarified this issue, because of early postnatal lethality. To examine this question, we generated mice with variable cellular mosaicism for null Insr alleles. Insr ablation in approximately 80% of cells caused extreme growth retardation, lipoatrophy, and hypoglycemia, a clinical constellation that resembles the human syndrome of leprechaunism. Insr ablation in 98% of cells, while resulting in similar growth retardation and lipoatrophy, caused diabetes without β-cell hyperplasia. The growth retardation was associated with a greater than 60-fold increase in the expression of hepatic insulin-like growth factor binding protein-1. These findings indicate that insulin regulates growth independently of metabolism and that the number of insulin receptors is an important determinant of the specificity of insulin action.

Insulin-like growth factor-I: compartmentalization within the somatotropic axis?

Insulin-like growth factor-I (IGF-I) is essential for normal growth; igf-1 gene mutations are associated with extreme growth retardation in mice and, very rarely, in humans. The relative contributions of tissue vs. endocrine (hepatic) IGF-I to the regulation of growth has been a fundamental question. New gene targeting technologies are providing answers for these questions.

Craniofacial morphology, dentition, and skeletal maturity in four siblings with Seckel syndrome.

To describe the craniofacial morphology, dentition, and hand maturity in four siblings with Seckel syndrome. Two boys and two girls, with Seckel syndrome. The children studied showed extreme growth retardation, severe microcephaly, bird-headed profile with receding chin, prominent nose, mental retardation, and extremely delayed skeletal maturation. The growth hormone axis and pituitary thyroid function was normal. Skeletal and dental development were investigated from radiographic material, and a cephalometric analysis was performed from profile radiographs. The craniums were remarkably small with an extremely short anterior cranial base (-4.3 to -5.5 standard units) and maxillary length (-3.8 to -4.7 SU). Differences in the morphology of the sella turcica were observed in girls and boys. Tooth maturity progressed normally. Tooth agenesis and tooth malformations were observed. Taurodontic root morphology was observed only in the girls. The approximate skeletal maturity showed retardation from 4 years 3 months to 4 years 11 months. Malformations of the hand-wrist skeleton occurred in the epiphyseal ossification centers of the middle phalangeal bone in the second, third, and fourth finger and in the distal phalangeal bone in the fifth finger. The epiphyseal ossification centers were lacking in the middle and distal phalangeal bones of the fifth finger. The underlying gene defect in the affected children seemingly affects bone development and growth but not dental maturation and eruption.

Hypokalemic salt-losing tubulopathy with chronic renal failure and sensorineural deafness.

To characterize a rare inherited hypokalemic salt-losing tubulopathy with linkage to chromosome 1p31. We conducted a retrospective analysis of the clinical data for 7 patients in whom cosegregation of the disease with chromosome 1p31 had been demonstrated. In addition, in 1 kindred, prenatal diagnosis in the second child was established, allowing a prospective clinical evaluation. Clinical presentation of the patients was homogeneous and included premature birth attributable to polyhydramnios, severe renal salt loss, normotensive hyperreninemia, hypokalemic alkalosis, and excessive hyperprostaglandin E-uria, which suggested the diagnosis of hyperprostaglandin E syndrome/antenatal Bartter syndrome. However, the response to indomethacin was only poor, accounting for a more severe variant of the disease. The patients invariably developed chronic renal failure. The majority had extreme growth retardation, and motor development was markedly delayed. In addition, all patients turned out to be deaf. The hypokalemic salt-losing tubulopathy with chronic renal failure and sensorineural deafness represents not only genetically but also clinically a disease entity distinct from hyperprostaglandin E syndrome/antenatal Bartter syndrome. A pleiotropic effect of a single gene defect is most likely causative for syndromic hearing loss.

Identification of a Bacillus subtilis secretion mutant using a -galactosidase screening procedure

High-level synthesis of exportable beta-galactosidase (LacZ) fusion proteins in Bacillus subtilis results in a lethal phenotype, and has been suggested as a tool for the selection of secretion mutants. We tested a plasmid-based, inducible lacZ fusion gene system for this purpose, but frequent mutations in cis, which reduced expression of the fusion gene, forced abandonment of the induction-selection strategy. Instead, after modification of the indicator plasmid, a screening procedure for increased basal LacZ activity levels was adopted. This led to the identification of a conditional B. subtilis secretion mutant after nitrosoguanidine mutagenesis. At 42 degrees C, but not at 30 degrees C, this mutant displayed extreme growth retardation when the LacZ fusion protein was produced, and and was also defective in the secretion of subtilisin Carlsberg. The processing kinetics and secretion of a subtilisin Carlsberg-alkaline phosphatase fusion derivative were found to be defective specifically at the non-permissive temperature. The secretion defect was not linked to the secA/div locus.

Immunoreactive growth hormone receptor/binding protein is present on fibroblasts and in serum of Laron-type dwarfs

Laron-type dwarfism is an autosomal recessive disorder characterised by extreme growth retardation and growth hormone (GH) resistance and has been shown in some cases to be associated with mutations in the GH receptor gene. Limited data suggest that in this condition specific liver GH binding is absent. In the majority of reported cases specific GH binding is also absent in serum. However it is not known whether the GH receptor and/or the serum GH binding protein are expressed in this condition. Using the techniques of immunohistochemistry and Northern blotting we have demonstrated that in cultured skin fibroblasts derived from four patients with Laron-type dwarfism the GH receptor gene is transcribed and the GH receptor protein is expressed on the cell surface. Further study of one of these patients, who has not previously been reported, has also revealed low but detectable levels of GH binding protein in serum using a two-site immunradiometric assay which does not depend on GH binding. These results indicate that the growth hormone receptor/binding protein is expressed in Laron-type dwarfism.