CHARGE syndrome: an update

CHARGE syndrome is a rare, usually sporadic autosomal dominant disorder due in 2/3 of cases to mutations within the CHD7 gene. The clinical definition has evolved with time. The 3C triad (Coloboma-Choanal atresia-abnormal semicircular Canals), arhinencephaly and rhombencephalic dysfunctions are now considered the most important and constant clues to the diagnosis. We will discuss here recent aspects of the phenotypic delineation of CHARGE syndrome and highlight the role of CHD7 in its pathogeny. We review available data on its molecular pathology as well as cytogenetic and molecular evidences for genetic heterogeneity within CHARGE syndrome.

CHARGE syndrome includes hypogonadotropic hypogonadism and abnormal olfactory bulb development

CONTEXT

CHARGE (coloboma, heart defect, choanal atresia, retarded growth and development, genital hypoplasia, ear abnormalities, and/or hearing loss defect) syndrome consists of a combination of congenital malformations including genital hypoplasia and retarded growth.

OBJECTIVE

The objective of the study was to study gonadotropic axis function and growth parameters in CHARGE syndrome.

DESIGN

This was a retrospective study.

PATIENTS

The study included 32 children with CHARGE syndrome.

RESULTS

Nineteen of 20 affected boys had micropenis and/or cryptorchidism, consistent with hypogonadotropic hypogonadism during fetal life. None of the boys was of pubertal age. Seven of nine boys tested before the age of 5 months during the neonatal peak period had extremely low testosterone levels. LH response to GnRH stimulation was variable during the first year of life and not correlated with existing clinical abnormalities. None of the girls over the age of 12 yr (n = 7) had begun puberty spontaneously, and a lack of response to GnRH stimulation was documented in five of them. Olfactory evaluation (n = 10) and magnetic resonance imaging (n = 18) of the forebrain revealed defective sense of smell and abnormal olfactory bulbs in all cases. Cardiorespiratory and nutritional problems were corrected, but the mean height of the 25 children who had reached 5 yr of age was -2 +/- 0.2 sd score. Height was not correlated with birth length or body mass index. GH deficiency was diagnosed in only three children.

CONCLUSION

These findings suggest that CHARGE syndrome includes the main features of Kallmann syndrome, which is defined by hypogonadotropic hypogonadism combined with a defective sense of smell and abnormal olfactory bulb development. This forebrain abnormality, if confirmed in a larger group of patients, could serve as a major new criterion for the diagnosis of CHARGE syndrome.

Inactivation of CUG-BP1/CELF1 causes growth, viability, and spermatogenesis defects in mice

CUG-BP1/CELF1 is a multifunctional RNA-binding protein involved in the regulation of alternative splicing and translation. To elucidate its role in mammalian development, we produced mice in which the Cugbp1 gene was inactivated by homologous recombination. These Cugbp1(-/-) mice were viable, although a significant portion of them did not survive after the first few days of life. They displayed growth retardation, and most Cugbp1(-/-) males and females exhibited impaired fertility. Male infertility was more thoroughly investigated. Histological examination of testes from Cugbp1(-/-) males showed an arrest of spermatogenesis that occurred at step 7 of spermiogenesis, before spermatid elongation begins, and an increased apoptosis. A quantitative reverse transcriptase PCR analysis showed a decrease of all the germ cell markers tested but not of Sertoli and Leydig markers, suggesting a general decrease in germ cell number. In wild-type testes, CUG-BP1 is expressed in germ cells from spermatogonia to round spermatids and also in Sertoli and Leydig cells. These findings demonstrate that CUG-BP1 is required for completion of spermatogenesis.

A syndrome of progressive pancytopenia with microcephaly, cerebellar hypoplasia and growth failure

A male infant with congenital thrombocytopenia, progressing to pancytopenia in the second year of life is presented. Other findings included microcephaly with cerebellar hypoplasia, growth failure of prenatal onset and severe psychomotor retardation. He died at 23 months of age from candida albicans septicemia. Laboratory studies and a postmortem examination failed to reveal any known etiology for his disorder, but parental consanguinity suggests a genetic basis with an autosomal recessive mode of inheritance. Høyeraal et al. have previously reported two brothers with similar clinical and laboratory findings. It is proposed that the condition of these three patients should be considered as a separate syndrome of congenital pancytopenia, distinguished from other congenital myeloid dysplasias by the extramedullary findings.

Distinct methylation changes at the IGF2-H19 locus in congenital growth disorders and cancer

BACKGROUND

Differentially methylated regions (DMRs) are associated with many imprinted genes. In mice methylation at a DMR upstream of the H19 gene known as the Imprint Control region (IC1) is acquired in the male germline and influences the methylation status of DMRs 100 kb away in the adjacent Insulin-like growth factor 2 (Igf2) gene through long-range interactions. In humans, germline-derived or post-zygotically acquired imprinting defects at IC1 are associated with aberrant activation or repression of IGF2, resulting in the congenital growth disorders Beckwith-Wiedemann (BWS) and Silver-Russell (SRS) syndromes, respectively. In Wilms tumour and colorectal cancer, biallelic expression of IGF2 has been observed in association with loss of methylation at a DMR in IGF2. This DMR, known as DMR0, has been shown to be methylated on the silent maternal IGF2 allele presumably with a role in repression. The effect of IGF2 DMR0 methylation changes in the aetiology of BWS or SRS is unknown.

METHODOLOGY/PRINCIPAL FINDINGS

We analysed the methylation status of the DMR0 in BWS, SRS and Wilms tumour patients by conventional bisulphite sequencing and pyrosequencing. We show here that, contrary to previous reports, the IGF2 DMR0 is actually methylated on the active paternal allele in peripheral blood and kidney. This is similar to the IC1 methylation status and is inconsistent with the proposed silencing function of the maternal IGF2 allele. Beckwith-Wiedemann and Silver-Russell patients with IC1 methylation defects have similar methylation defects at the IGF2 DMR0, consistent with IC1 regulating methylation at IGF2 in cis. In Wilms tumour, however, methylation profiles of IC1 and IGF2 DMR0 are indicative of methylation changes occurring on both parental alleles rather than in cis.

CONCLUSIONS/SIGNIFICANCE

These results support a model in which DMR0 and IC1 have opposite susceptibilities to global hyper and hypomethylation during tumorigenesis independent of the parent of origin imprint. In contrast, during embryogenesis DMR0 is methylated or demethylated according to the germline methylation imprint at the IC1, indicating different mechanisms of imprinting loss in neoplastic and non-neoplastic cells.

Epigenetic deregulation of imprinting in congenital diseases of aberrant growth

Human chromosome 11p15 comprises two imprinted domains important in the control of fetal and postnatal growth. Novel studies establish that imprinting at one of these, the IGF2-H19 domain, is epigenetically deregulated (with loss of DNA methylation) in Silver-Russell Syndrome (SRS), a congenital disease of growth retardation and asymmetry. Previously, the exact opposite epigenetic alteration (gain of DNA methylation) had been detected at the domain's 'imprinting control region' (ICR) in patients with Beckwith-Wiedemann Syndrome (BWS), a complex disorder of fetal overgrowth. However, more frequently, BWS is caused by loss of DNA methylation at the ICR that regulates the second imprinted domain at 11p15. Interestingly, a similar epigenetic alteration (with loss of methylation) at a putative ICR on human chromosome 6q24, is involved in transient neonatal diabetes mellitus (TNDM), a congenital disease with intrauterine growth retardation and a transient lack of insulin. Thus, fetal and postnatal growth is epigenetically controlled by different ICRs, at 11p15 and other chromosomal regions.

The results of limb lengthening by callus distraction using an extending intramedullary nail (Fitbone) in non-traumatic disorders

Limb lengthening by callus distraction and external fixation has a high rate of complications. We describe our experience using an intramedullary nail (Fitbone) which contains a motorised and programmable sliding mechanism for limb lengthening and bone transport. Between 2001 and 2004 we lengthened 13 femora and 11 tibiae in ten patients (seven men and three women) with a mean age of 32 years (21 to 47) using this nail. The indications for operation were short stature in six patients and developmental or acquired disorders in the rest.

The mean lengthening achieved was 40 mm (27 to 60). The mean length of stay in hospital was seven days (5 to 9). The mean healing index was 35 days/cm (18.8 to 70.9). There were no cases of implant-related infection or malunion.

Solitary median maxillary central incisor (SMMCI) syndrome

Solitary median maxillary central incisor syndrome (SMMCI) is a complex disorder consisting of multiple, mainly midline defects of development resulting from unknown factor(s) operating in utero about the 35th-38th day(s) from conception. It is estimated to occur in 1:50,000 live births. Aetiology is uncertain. Missense mutation in the SHH gene (I111F) at 7q36 may be associated with SMMCI. The SMMCI tooth differs from the normal central incisor, in that the crown form is symmetric; it develops and erupts precisely in the midline of the maxillary dental arch in both primary and permanent dentitions. Congenital nasal malformation (choanal atresia, midnasal stenosis or congenital pyriform aperture stenosis) is positively associated with SMMCI. The presence of an SMMCI tooth can predict associated anomalies and in particular the serious anomaly holoprosencephaly. Common congenital anomalies associated with SMMCI are: severe to mild intellectual disability, congenital heart disease, cleft lip and/or palate and less frequently, microcephaly, hypopituitarism, hypotelorism, convergent strabismus, oesophageal and duodenal atresia, cervical hemivertebrae, cervical dermoid, hypothyroidism, scoliosis, absent kidney, micropenis and ambiguous genitalia. Short stature is present in half the children. Diagnosis should be made by eight months of age, but can be made at birth and even prenatally at 18-22 weeks from the routine mid-trimester ultrasound scan. Management depends upon the individual anomalies present. Choanal stenosis requires emergency surgical treatment. Short stature may require growth hormone therapy. SMMCI tooth itself is mainly an aesthetic problem, which is ideally managed by combined orthodontic, prosthodontic and oral surgical treatment; alternatively, it can be left untreated.

Macrodactyly, hemihypertrophy, and connective tissue nevi: report of a new syndrome and review of the literature

Macrodactyly and hemihypertrophy have been described in association with a number of syndromes which are reviewed. We describe a child who, in addition to macrodactyly and hemihypertrophy, has extensive connective tissue nevi. He does not conform to any known entity and would appear to represent a "new" syndrome.

Solitary maxillary central incisor and congenital nasal pyriform aperture stenosis

Solitary maxillary central incisor (SMCI) and congenital nasal pyriform aperture stenosis (CNPAS) have been reported as an isolated morphogenic defect or associated with pituitary deficiency, holoprosencephaly, ocular coloboma, or chromosomal abnormalities. We report two cases and analyse 40 cases of SMCI and 24 cases of CNPAS, including 15 cases of combined SMCI and CNPAS, obtained from the literature. Of the patients with SMCI, 69% had short stature, 48% growth hormone deficiency or hypopituitarism, 23% pituitary absence or hypoplasia, and 17% had del (18p-) or r(18). Of the patients with CNPAS, 63% had SMCI, 75% were short, 43% had hypopituitarism or growth hormone deficiency, 36% had pituitary or CNS anomaly, and 33% had del (18p), r(18), or del (13q).

CONCLUSIONS

Solitary maxillary central incisor and congenital nasal pyriform aperture stenosis can be a diagnostic clue to pituitary hypofunction, CNS, ophthalmological and cytogenic anomalies.

Mutation analysis of the NSD1 gene in a group of 59 patients with congenital overgrowth

Sotos syndrome is characterized by pre- and post-natal overgrowth, typical craniofacial features, advanced bone age, and developmental delay. Some degree of phenotypic overlap exists with other overgrowth syndromes, in particular with Weaver syndrome. Sotos syndrome is caused by haploinsufficiency of the NSD1 (nuclear receptor SET domain containing gene 1) gene. Microdeletions involving the gene are the major cause of the syndrome in Japanese patients, whereas intragenic mutations are more frequent in non-Japanese patients. NSD1 aberrations have also been described in some patients diagnosed as Weaver syndrome. Some authors have suggested a certain degree of genotype-phenotype correlation, with a milder degree of overgrowth, a more severe mental retardation, and a higher frequency of congenital anomalies in microdeleted patients. Data on larger series are needed to confirm this suggestion. We report here on microdeletion and mutation analysis of NSD1 in 59 patients with congenital overgrowth. Fourteen novel mutations, two previously described and one microdeletion were identified. All patients with a NSD1 mutation had been clinically classified as "classical Sotos," although their phenotype analysis demonstrated that some major criteria, such as overgrowth and macrocephaly, could be absent. All patients with confirmed mutations shared the typical Sotos facial gestalt. A high frequency of congenital heart defects was present in patients with intragenic mutations, supporting the relevance of the NSD1 gene in the pathogenesis of this particular defect.

Narrowing critical regions and determining penetrance for selected 18q- phenotypes

One of our primary goals is to help families who have a child with an 18q deletion anticipate medical issues in order to optimize their child's medical care. To this end we have narrowed the critical regions for four phenotypic features and determined the penetrance for each of those phenotypes when the critical region for that feature is hemizygous. We completed molecular analysis using oligo-array CGH and clinical assessments on 151 individuals with deletions of 18q and made genotype-phenotype correlations defining or narrowing critical regions. These nested regions, all within 18q22.3 to q23, were for kidney malformations, dysmyelination of the brain, growth hormone stimulation response failure, and aural atresia. The region for dysmyelination and growth hormone stimulation response failure were identical and was narrowed to 1.62 Mb, a region containing five known genes. The region for aural atresia was 2.3 Mb and includes an additional three genes. The region for kidney malformations was 3.21 Mb and includes an additional four genes. Penetrance rates were calculated by comparing the number of individuals hemizygous for a critical region with the phenotype to those without the phenotype. The kidney malformations region was 25% penetrant, the dysmyelination region was 100% penetrant, the growth hormone stimulant response failure region was 90% penetrant with variable expressivity, and the aural atresia region was 78% penetrant. Identification of these critical regions suggest possible candidate genes, while penetrance calculations begin to create a predictive phenotypic description based on genotype.

Omodysplasia

Three cases of a new congenital bone disorder associating facial anomalies (depressed nasal bridge, broad base of the nose, long philtrum) with short humeri. The complex skeletal abnormalities consist of a defect of growth of the distal end of the humerus, a hypoplastic everted condyle, an upper radioulnar diastasis, and a anterolateral dislocation of the head of the radius. The condition is dominantly inherited. Two other cases with the same facial anomalies and osteoarticular abnormalities of the upper limbs are described. These cases also showed a severe micromelic dwarfism due to shortness of the long bones, particularly the femora. The present authors consider that these represent variable expressivity of the same disorder and propose that this condition be called omodysplasia (from the Greek term for humerus).

KBG syndrome

KBG syndrome is a rare condition characterised by a typical facial dysmorphism, macrodontia of the upper central incisors, skeletal (mainly costovertebral) anomalies and developmental delay. To date, KBG syndrome has been reported in 45 patients. Clinical features observed in more than half of patients that may support the diagnosis are short stature, electroencephalogram (EEG) anomalies (with or without seizures) and abnormal hair implantation. Cutaneous syndactyly, webbed short neck, cryptorchidism, hearing loss, palatal defects, strabismus and congenital heart defects are less common findings. Autosomal dominant transmission has been observed in some families, and it is predominantly the mother, often showing a milder clinical picture, that transmits the disease. The diagnosis is currently based solely on clinical findings as the aetiology is unknown. The final diagnosis is generally achieved after the eruption of upper permanent central incisors at 7–8 years of age when the management of possible congenital anomalies should have been already planned. A full developmental assessment should be done at diagnosis and, if delays are noted, an infant stimulation program should be initiated. Subsequent management and follow-up should include an EEG, complete orthodontic evaluation, skeletal investigation with particular regard to spine curvatures and limb asymmetry, hearing testing and ophthalmologic assessment.

A broader spectrum of abnormalities in the prune belly syndrome

The clinical course of 25 children with the prune belly syndrome was reviewed retrospectively to assess the over-all morbidity associated with this disorder. There were 3 neonatal deaths of renal or pulmonary disease. Chronic renal insufficiency or end stage renal disease developed in 5 survivors, all of whom had impaired kidney function in early infancy. An additional 17 patients survived with only mild renal insufficiency. Growth retardation, which correlated poorly with renal function, was present in a third of the patients. Clinically significant pulmonary and orthopedic problems were noted in 55 per cent of the survivors. Chronic constipation was another common, although less serious, feature. This report emphasizes the severity of the extrarenal problems associated with the prune belly syndrome.

Maternal uniparental heterodisomy of chromosome 14: chromosomal mechanism and clinical follow up

To our knowledge, 22 cases of chromosome 14 maternal uniparental disomy (UPD(14)mat) have been reported so far. The majority of cases were ascertained because of an abnormal phenotype associated with a Robertsonian translocation involving chromosome 14. We report here on a child with UPD(14)mat detected prenatally and resulting from trisomy rescue in a maternal meiosis I non-disjunction trisomic zygote. After four years of clinical follow up, in addition to intrauterine growth retardation (IUGR), only short stature and small hands and feet were observed. These clinical data as well as the ascertainment and mechanism of origin of UPD(14)mat were compared with those observed in previously reported cases. It appears that the clinical spectrum of UPD(14)mat is milder in our patient than in patients with UPD(14)mat resulting from other chromosomal mechanisms. In addition, a hypothesis based on abnormal imprinting is proposed to explain the variability of the UPD(14)mat.

Ophthalmologic findings in the Cornelia de Lange syndrome

Cornelia de Lange Syndrome (CDLS) is characterized by mental retardation, growth retardation, skeletal anomalies, and a characteristic facies. We examined 22 children with CDLS to ascertain the relative frequencies of oculofacial and ophthalmologic abnormalities. We confirm prior reports of the frequent findings of brow hypertrichosis, synophrys, and long arcuate eyelashes. In addition we documented the association with ptosis, nystagmus, and high myopia. Contrary to previous reports, we did not find blue sclera or corneal, pupillary, or retinal disorders to be part of this syndrome. Hypertelorism and telecanthus were found, but they were dependent on the method of calculation. Two children had optic nerve pallor. We also report the new findings of poor macular reflex, chin lifts induced by ptosis, hypertropia, and nasolacrimal duct fistula.

Growth in CHARGE association

Growth data is shown from 44 children (aged 0.5-18 years; 27 boys, 17 girls) with CHARGE association. Children had a normal birth weight and length, but in infancy there was a fall in centiles. Children remained small and there was pubertal delay in boys. Close monitoring of growth with early detection and intervention is recommended.

Costello syndrome with growth hormone deficiency and hypoglycemia: A new report and review of the endocrine associations

We describe an 18-month-old boy with Costello syndrome (CS) with proven partial growth hormone (GH) deficiency and hypoglycemic episodes. The hypoglycemia is deemed to be due to cortisol deficiency. This report represents the second published case of cortisol deficiency in the CS. A brief review of the endocrine disturbances in the syndrome is provided. We highlight the need for careful endocrinological evaluation of individuals with CS.

Growth hormone deficiency in Costello syndrome

We report on three patients with Costello syndrome and isolated growth hormone (GH) deficiency treated with biosynthetic GH. To our knowledge, these are the only patients with Costello syndrome who have been successfully treated for GH deficiency. We review the pathophysiology of Costello syndrome and highlight the recent recommendations of tumor screening and cardiac surveillance in this population, of particular relevance to those receiving GH therapy.

Clinical variability in congenital fiber type disproportion

Congenital Fiber Type Disproportion (CFTD) has recently been described as a consistent and stereotyped clinicopathological entity, including congenital nonprogressive hypotonia and weakness, contractures, kyphoscoliosis, high arched palate, dislocated hips, short stature, and feet deformities. Our personal experience with this condition suggests a wider disparity in the physical appearance and associated abnormalities of affected individuals than the well-defined clinical syndrome previously described. We are presenting 5 cases, including 2 siblings, whose muscle biopsies satisfy the major histological and statistical criteria for the diagnosis. Although each child clearly had hypotonia and weakness consistent with a congenital myopathy, only 3 had a sufficient number of other similarities to establish the diagnosis clinically. The clinical spectrum of the other cases ranged from one infant whose only abnormality was mild hypotonia in the legs to another whose problems included severe motor impairment, marked mental retardation, growth failure, frontal bossing, abnormal hair, and scoliosis. Even in retrospect, the diagnosis of CFTD could not have been supported on clinical grounds alone. Therefore, CFTD is a congenital myopathy whose diagnosis can be made only by muscle biopsy, rather than a distinct syndrome whose diagnosis can be assumed on the basis of clinical characteristics alone.

Sizes of abdominal organs in adults with severe short stature due to severe, untreated, congenital GH deficiency caused by a homozygous mutation in the GHRH receptor gene

OBJECTIVE

To assess the sizes of intra-abdominal organs of adult subjects with untreated severe congenital isolated GH deficiency (IGHD) due to lack of functional GHRH receptor (GHRH-R), and to verify whether there is proportionality between size of organ and adult stature and body surface area (BSA).

SUBJECTS AND METHODS

By using ultrasound, we studied the sizes (absolute and corrected by height, weight and BSA) of the intra-abdominal organs of 18 adult subjects with IGHD (eight females, IGHD group) who have never received GH replacement therapy. They were all homozygous for the same null mutation (IVS1 + 1G --> A) in the GHRH receptor gene (GHRH-R). They were compared with normal controls from the same region.

RESULTS

After correction for BSA, subjects lacking a functional GHRH-R have normal prostate and ovaries size, small spleen and uterus, and large liver, pancreas and kidney.

CONCLUSIONS

Size of individual abdominal organs is influenced in different ways by severe and congenital lack of GH due to a GHRH-R mutation.

Oral-dental findings in dyskeratosis congenita

A 13-yr-old girl with dyskeratosis congenita is presented. Besides oral leukoplakia and nail dystrophies, there was evidence of pancytopenia, growth retardation, alopecia, mental retardation and microcephaly. The oral findings included caries, gingival recession, short-blunted roots, gingival bleeding, tooth mobility and severe alveolar bone loss resembling juvenile periodontitis.

New observations on midline defects: coincidence of anophthalmos, microphthalmos and cryptophthalmos with hypothalamic disorders

Four children with severe congenital eye anomalies are described of which three had related symptoms. Two had bilateral anophthalmia, the optic nerves not detectable by computed cranial tomography and magnetic resonance imaging, and the third child had bilateral microphthalmia and coloboma iridis. The fourth patient had bilateral cryptophthalmia as part of Fraser syndrome. All four patients were of small stature. In three of them growth hormone deficiency was demonstrated which was of hypothalamic origin as shown by growth hormone releasing hormone tests. In the fourth child hypogonadotropic hypogonadism and tertiary thyroid deficiency were diagnosed which responded well to thyroxine treatment. Pathogenetically the described disorders are due to congenital defects of midline structures as a common "developmental field".