The genomic basis of cerebral palsy: a HuGE systematic literature review

Cerebral palsy has been associated with a number of candidate genes. To date, no systematic review has been conducted to synthesise genetic polymorphism associations with cerebral palsy. We apply the HuGE NET guidelines to search PubMed and EMBASE databases for publications investigating single nucleotide polymorphisms (SNPs) and cerebral palsy outcome. 22 papers were identified and are discussed in this review. Candidate genes were grouped as (1) thrombophilic, (2) cytokine, (3) apolipoprotein E or (4) other SNPs, largely related to cardiovascular physiology/pathophysiology and the functioning of the immune system. Of the studies identified, cohorts were usually small, without adequate control and ethnically diverse, making direct comparison between studies difficult. The most promising candidate genes include factor V Leiden, methylenetetrahydrofolate reductase, lymphotoxin-alpha, tumour necrosis factor-alpha, eNOS and mannose binding lectin. Large case-control studies are needed to confirm these candidates with attention given to cohort ethnicity, cerebral palsy subtype analysis and possible multiple gene and gene-environment interactions.

Fetal exposure to herpesviruses may be associated with pregnancy-induced hypertensive disorders and preterm birth in a Caucasian population

OBJECTIVE

To investigate the role of fetal viral infection in the development of a range of adverse pregnancy outcomes (APOs), including pregnancy-induced hypertensive disorders (PIHD), antepartum haemorrhage (APH), birthweight <10th percentile (small for gestational age, SGA) and preterm birth (PTB).

DESIGN

Population-based case-control study.

SETTING

Laboratory-based study.

POPULATION

The newborn screening cards of 717 adverse pregnancy cases and 609 controls.

METHODS

Newborn screening cards were tested for RNA from enteroviruses and DNA from herpesviruses using polymerase chain reaction (PCR). The herpesviruses were detected using two PCRs, one detecting nucleic acids from herpes simplex virus (HSV)-1, HSV-2, Epstein-Barr virus (EBV), cytomegalovirus (CMV) and human herpesvirus (HHV)-8, hereafter designated Herpes PCR group A viruses, and the other detecting nucleic acids from varicella-zoster virus (VZV), HHV-6 and HHV-7, hereafter designated Herpes PCR group B viruses.

MAIN OUTCOME MEASURE

Odds ratios and 95% CIs for specific APOs.

RESULTS

For both term and PTBs, the risk of developing PIHD was increased in the presence of DNA from Herpes PCR group B viruses (OR 3.57, 95% CI 1.10-11.70), CMV (OR 3.89, 95% CI 1.67-9.06), any herpesvirus (OR 5.70, 95% CI 1.85-17.57) and any virus (OR 5.17, 95% CI 1.68-15.94). The presence of CMV was associated with PTB (OR 1.61, 95% CI 1.14-2.27). No significant association was observed between SGA or APH and exposure to viral infection.

CONCLUSIONS

Fetal exposure to herpesvirus infection was associated with PIHD for both term and PTBs in this exploratory study. Exposure to CMV may also be associated with PTB. These findings need confirmation in future studies.

FBN1, TGFBR1, and the Marfan-craniosynostosis/mental retardation disorders revisited

The recent identification of TGFBR2 mutations in Marfan syndrome II (MFSII) [Mizuguchi et al. (2004); Nat Genet 36:855-860] and of TGFBR1 and TGFBR2 mutations in Loeys-Dietz aortic aneurysm syndrome (LDS) [Loeys et al. (2005); Nat Genet 37:275-281] [OMIM 609192] has provided direct evidence of abnormal signaling in transforming growth factors beta (TGF-beta) in the pathogenesis of Marfan syndrome (MFS). In light of this, we describe the phenotypes and genotypes of five individuals. Patient 1 had MFS and abnormal cranial dura. Patient 2 had severe early onset MFS and an abnormal skull. Patients 3 and 4 had probable Furlong syndrome (FS). Patient 5 had marfanoid (MD) features, mental retardation (MR), and a deletion of chromosome 15q21.1q21.3. All patients had a condition within the MFS, MD-craniosynostosis (CS) or MD-MR spectrum. The names of these entities may become redundant, and instead, come to be considered within the spectrum of TGF-beta signaling pathway disorders. Two recurrent heterozygous FBN1 mutations were found in Patients 1 and 2, and an identical novel heterozygous de novo TGFBR1 mutation was found in Patients 3 and 4, in whom altered fibrillin-1 processing was demonstrated previously [Milewicz et al. (2000); Am J Hum Genet 67:279]. A heterozygous FBN1 deletion was found in Patient 5. These findings support the notion that perturbation of extracellular matrix homeostasis and/or remodeling caused by abnormal TGF-beta signaling is the core pathogenetic mechanism in MFS and related entities including the MD-CS syndromes.

PEHO and PEHO-like syndromes: report of five Australian cases

PEHO syndrome is a rare progressive infantile encephalopathy with onset within the first few months of life. Few patients fulfilling the diagnostic criteria for PEHO syndrome have been reported outside Finland. Affected infants have facial dysmorphism and suffer from severe hypotonia, profound mental retardation, convulsions (often with a hypsarrhythmic EEG pattern), transient or persistent peripheral oedema, and optic atrophy. Cerebellar and brainstem atrophy are usually present on neuroimaging. A PEHO-like syndrome has been described, in which the affected individuals have neither optic atrophy nor the typical neuroradiological findings. We report five Australian patients, the first with classical features of PEHO syndrome, and four who have a PEHO-like disorder. We compare their features with other published cases. We suggest that PEHO or a PEHO-like syndrome may affect more patients than are currently identified, based on the original diagnostic criteria for this disorder.

A familial cryptic subtelomeric deletion 12p with variable phenotypic effect

A 15-year-old-boy and his mother, both carrying a cryptic deletion within 12p13.33, are described. The proband has a mild phenotype with moderate mental retardation and severe behavioural problems. The mother had some learning difficulties at school. Conventional GTL-banded high-resolution chromosome analysis showed normal karyotypes. Subsequent analysis by fluorescence in situ hybridization using a set of probes specific for the subtelomeric regions of all chromosomes, plus a series of probes at 12p13.33 extending from the 12p telomere, showed that both mother and son carry a 1.65 Mb terminal deletion in this region. There are 10 predicted genes within the deleted region. The unanticipated familial nature of the deletion emphasizes the value of family studies in all cases with subtelomeric abnormalities. It also demonstrates the difficulty in making a clinical diagnosis of individuals with this deletion. To the best of the present authors' knowledge, the proband and his mother are the first patients described with a submicroscopic deletion at 12p13.33.

Hemifacial microsomia: progress in understanding the genetic basis of a complex malformation syndrome

Hemifacial microsomia (HFM) is a common birth defect involving first and second branchial arch derivatives. The phenotype is extremely variable. In addition to craniofacial anomalies there may be cardiac, vertebral and central nervous system defects. The majority of cases are sporadic, but there is substantial evidence for genetic involvement in this condition, including rare familial cases that exhibit autosomal dominant inheritance. As an approach towards identifying molecular pathways involved in ear and facial development, we have ascertained both familial and sporadic cases of HFM. A genome wide search for linkage in two families with features of HFM was performed to identify the disease loci. In one family data were highly suggestive of linkage to a region of approximately 10.7 cM on chromosome 14q32, with a maximum multipoint lod score of 3.00 between microsatellite markers D14S987 and D14S65. This locus harbours the Goosecoid gene, an excellent candidate for HFM based on mouse expression and phenotype data. Coding region mutations were sought in the familial cases and in 120 sporadic cases, and gross rearrangements of the gene were excluded by Southern blotting. Evidence for genetic heterogeneity is provided by the second family, in which linkage was excluded from this region.

Karyotypes found in the population declared at increased risk of Down syndrome following maternal serum screening

Of the 65 328 pregnancies of South Australian mothers screened by the South Australian Maternal Serum Antenatal Screening (SAMSAS) Programme between 1 January 1991 and 31 December 1997, 3431 (5.25%) were declared at increased risk of fetal Down syndrome. Fetal or neonatal karyotype was determined in 2737/3431 (79.8%) of these pregnancies, including 16 with early fetal loss. Interrogation of the database of the South Australian Neonatal Screening Service showed 643 live-born infants whose phenotype was not subsequently questioned among the 694 pregnancies whose karyotype was not determined. Of the remaining 51/3431 pregnancies, 19 ended in early fetal loss without karyotyping and no newborn screening or other records could be found for 32 cases. The 129 instances of abnormal karyotype found were Down syndrome (84), trisomy 18 (four), trisomy 13 (three), triploidy (two), female sex chromosome aneuploidy (six) and male sex chromosome aneuploidy (five), inherited balanced rearrangements (19), mosaic or de novo balanced abnormalities (four) and unbalanced karyotypes (two). In the pregnancies declared at increased risk of fetal Down syndrome, only the karyotype for Down syndrome occurred with a frequency greater than that expected for the general, pregnant population.

The impact of maternal serum screening on the birth prevalence of Down's syndrome and the use of amniocentesis and chorionic villus sampling in South Australia

OBJECTIVES

To describe the impact of maternal serum screening on the birth prevalence of Down's syndrome and on the use of amniocentesis and chorionic villus sampling in South Australia.

DESIGN

A descriptive population-based study.

SETTING

South Australia (population 1.48 million persons; approximately 20,000 births per year).

PARTICIPANTS

Women who had births or terminations of pregnancy with Down's syndrome in 1982-1996, women who had maternal serum screening in 1991-1996, amniocentesis or chorionic villus sampling in 1986-1996.

METHODS

Analysis of data from multiple sources on maternal serum screening, amniocentesis and chorionic villus sampling, births and terminations of pregnancy.

MAIN OUTCOME MEASURES

Total prevalence and birth prevalence of Down's syndrome each year in 1982-1996; proportion of pregnant women using maternal serum screening in 1991-1996, and proportion using amniocentesis and chorionic villus sampling by indication in 1986-1996, by age group.

RESULTS

Use of maternal serum screening for Down's syndrome increased from 17% when introduced in 1991 to 76% of women who gave birth in 1996. Between 1982 and 1986 and 1996, terminations of pregnancy for fetal Down's syndrome increased from 7.1 % to 75% and the birth prevalence of Down's syndrome fell by 60% from 1.05 to 0.42 per 1,000 births, against the background of an increase in total prevalence due to increasing maternal age. The use of amniocentesis increased from 5.8% in 1991 to 10.1% in 1996 mainly due to the increase among women younger than 35 years with maternal serum screening as the main reason. The increasing chorionic villus sampling rate among younger women stabilised at 0.4%, while the rate among older women decreased from 11.0% to 7.4%.

CONCLUSIONS

The introduction of maternal serum screening in South Australia has resulted in increased use of any prenatal testing for Down's syndrome from about 7% (mainly older women having amniocentesis or chorionic villus sampling) to 84% of women (about 8% having direct amniocentesis or chorionic villus sampling and 76% having maternal serum screening first). This has resulted in a significant fall in the birth prevalence of Down's syndrome. maternal serum screening was the first indication of Down's syndrome for about half the terminations of pregnancy for Down's syndrome in 1993-1996, including three quarters of those in younger women.

Homozygotes for FRA16B are normal

Homozygotes for the rare folate-sensitive autosomal fragile sites have never been recorded. Two non-folate-sensitive rare fragile sites (FRA10B and FRA17A) have been previously recorded in normal individuals. We document two unrelated normal individuals who are homozygotes for the rare fragile site FRA16B and record the patterns of induction of this fragile site with berenil. The existence of normal homozygotes for FRA16B suggests that this fragile site is not within a gene essential for normal development.

Origins of accessory small ring marker chromosomes derived from chromosome 1

Three patients with accessory small ring chromosomes derived from chromosome 1 are presented together with additional clinical details and cytogenetic analyses of a previously reported patient. Cytogenetic analysis was undertaken by FISH using a reverse painting probe generated from one of the patients by microdissection of the r(1) chromosome and with a BAC923C6 which maps to 1p12. Results indicated that patients with r(1) chromosomes consisting of 1q12 heterochromatin and short arm pericentric euchromatin which extends to at least the BAC923C6 were associated with a normal or mild phenotype. Patients with abnormal phenotypes possessed two types of rings. One patient had evidence for contiguous pericentric short arm euchromatin which extended from the centromere to beyond the BAC923C6. Two patients showed molecular cytogenetic results which were compatible with non-contiguous chromosome 1 euchromatin. The diversity of origin of r(1)s will hamper attempts to define phenotype/genotype relationships.

Analysis of five Duchenne muscular dystrophy exons and gender determination using conventional duplex polymerase chain reaction on single cells

We have developed five conventional duplex polymerase chain reaction (PCR) protocols on single lymphocytes and blastomeres from embryos, in order to analyse five exons commonly deleted in deletion-type Duchenne muscular dystrophy (DMD). The five DMD gene exons (17, 19, 44, 45 and 48) can be analysed in separate duplex PCR reactions together with the sex-determining region Y (SRY) gene which enables simultaneous gender assignment. We present here PCR amplification results from single lymphocytes isolated from a normal male (220 cells), a normal female (24 cells) and a male DMD patient (40 cells) carrying a deletion of exons 46-49 within the DMD gene. The method failed to produce a PCR signal for the SRY gene in 8/220 normal male cells (3.6%) and for a DMD exon in 0-4.5% of normal male cells. One negative control out of 112 was positive. When this method was used to analyse two blastomeres from each of five embryos, concordant results were obtained for each pair of blastomeres. All embryos produced signals for the DMD exon tested with four of the embryos found to be male and one female. This method is therefore suitable for preimplantation genetic diagnosis and will allow the transfer of healthy embryos (both male and female) in families carrying DMD gene deletions involving at least one of the five exons 17, 19, 44, 45 and 48.

Aortic dissection, patent ductus arteriosus, iris hypoplasia and brachytelephalangy in a male adolescent

We describe a 14-year-old male with dissection of the descending aorta, bilateral iris hypoplasia, striae distensae and brachytelephalangy, the latter being most marked in the thumbs. Inguinal herniae and a patent ductus arteriosus were surgically repaired in infancy. The pattern of abnormalities may constitute a previously undescribed syndrome. The proband died suddenly at the age of 17 years.

The impact of rubella immunisation on the incidence of rubella, congenital rubella syndrome and rubella-related terminations of pregnancy in South Australia

OBJECTIVES

To describe the impact of rubella immunisation on the incidence of rubella, congenital rubella syndrome and rubella-related terminations of pregnancy in South Australia, and to identify factors associated with a re-emerging problem.

DESIGN AND METHODS

A population-based descriptive study using data from South Australian notifications of disease, births and terminations of pregnancy, the rubella immunisation programme, antenatal rubella antibody screening and paediatric hospital case records.

SETTING

South Australia (population 1.48 million people; 20,000 births per year).

MAIN OUTCOME MEASURES

Incidence of rubella (age-sex specific), congenital rubella syndrome and rubella-related terminations of pregnancy; antenatal rubella sero-positive rates; rubella immunisation uptake rates.

RESULTS

Rubella notification rates in 1990-1996 were significantly higher for males than females for ages 15-34 years. There were five cases of congenital rubella syndrome notified in 1980-1996 compared with at least 20 confirmed or compatible cases in 1965-1979. Rubella-related terminations of pregnancy are now rare, with the last termination for maternal rubella being in 1993. The antenatal rubella sero-positive rate in 1995 was 96.7%, but was significantly lower among Asian women born overseas (78.6% among those 30 years or older). Vaccination uptake rates in schoolgirls decreased between 1990 and 1994 (91.2% to 86.9%).

CONCLUSIONS

Since the introduction of rubella immunisation, the incidence of rubella infection among women of reproductive age, and of rubella-related terminations, has fallen. Congenital rubella syndrome has not been notified since 1990 but its risk persists with a recent increase in rubella notifications, a fall in school immunisation rates, a relatively low antenatal sero-positive rate among older Asian women born overseas and the trend towards giving birth at older ages. Effective immunisation programmes must be maintained, particularly in schools and for young children and migrant women.

High resolution characterization of an interstitial deletion of less than 1.9 Mb at 4p16.3 associated with Wolf-Hirschhorn syndrome

Wolf-Hirschhorn syndrome (WHS) caused by 4p16.3 deletions comprises growth and mental retardation, distinct facial appearance and seizures. This study characterized a subtle interstitial deletion of 4p16.3 in a girl with mild retardation and possessing facial traits characteristic of WHS. The patient had generalized seizures in conjunction with fever at 3 and 5 years of age. Fluorescence in situ hybridization (FISH) with a series of markers in the 4p16.3 region showed that the interstitial deletion in this patient was between the probes D4S96 and D4S182, enabling the size of the deletion to be estimated as less than 1.9 Mb. This is the smallest interstitial deletion of 4p16.3 which has been reported. The patient contributes to a refinement of the phenotypic map of the WHS region in 4p16.3. The critical region for the characteristic facial changes of WHS, failure to thrive and developmental delay is now localized to a region of less than 700 kb. The mental retardation of this patient was mild suggesting that small interstitial deletion may have less severe phenotypic consequences.

FMR2 expression in families with FRAXE mental retardation

Normal individuals express the two alternative transcripts, FMR2 and Ox19, from the FRAXE-associated CpG island. Molecular analysis of the Ox19 transcript suggests that it is a truncated isoform of the FMR2 gene with an alternative 3' end. Both isoforms showed a similar pattern of expression, with the Ox19 isoform expressed at a much lower level. Fibroblasts, chorionic villi and hair roots showed the highest level of FMR2 expression, whole blood cells and amniocytes showed very low expression, and the transcript was not detected in lymphoblasts. Fibroblasts of 11 individuals from seven families segregating FRAXE were assayed for FMR2 expression and FRAXE CpG island methylation. A man with an unmethylated expansion of 0.6 kb expressed FMR2 and represents a pre-mutation carrier. All chromosomes with FRAXE CCG expansions of 0.8 kb or greater were fully methylated and did not express the FMR2 gene, analogous to the mechanism of silencing the FMR1 gene in carriers of the FRAXA full mutation. The boundary between FRAXE pre-mutation and FRAXE full mutation is between 0.7 and 0.8 kb. Two men with absence of FMR2 expression in fibroblasts were not mentally impaired, suggesting that IQ in some men with FRAXE full mutation may remain within the normal range. Although molecular tools to study FRAXE non-specific mental retardation are now available, further psychometric and molecular studies are needed to characterize the effect of the FRAXE full mutation for the purpose of genetic counselling.

Perinatal risk factors for developmental dysplasia of the hip

AIMS

To identify perinatal risk factors for developmental dysplasia of the hip (DDH) and define the risk for each factor.

METHODS

In this case control study, using logistic regression analysis, all 1127 cases of isolated DDH live born in South Australia in 1986-93 and notified to the South Australian Birth Defects Register were included; controls comprised 150130 live births in South Australia during the same period without any notified congenital abnormalities.

RESULTS

Breech presentation, oligohydramnios, female sex and primiparity were confirmed as risk factors for DDH. Significant findings were an increased risk for vaginal delivery over caesarean section for breech presentation (as well as an increased risk for emergency section over elective section), high birthweight (> or = 4000 g), postmaturity and older maternal age; multiple births and preterm births had a reduced risk. There was no increased risk for caesarean section in the absence of breech presentation. For breech presentation, the risk of DDH was estimated to be at least 2.7% for girls and 0.8% for boys; a combination of factors increased the risk.

CONCLUSIONS

It is suggested that the risk factors identified be used as indications for repeat screening at 6 weeks of age and whenever possible in infancy. Other indications are family history and associated abnormalities.

A unique point mutation in the fibroblast growth factor receptor 3 gene (FGFR3) defines a new craniosynostosis syndrome

The underlying basis of many forms of syndromic craniosynostosis has been defined on a molecular level. However, many patients with familial or sporadic craniosynostosis do not have the classical findings of those craniosynostosis syndromes. Here we present 61 individuals from 20 unrelated families where coronal synostosis is due to an amino acid substitution (Pro250Arg) that results from a single point mutation in the fibroblast growth factor receptor 3 gene on chromosome 4p. In this instance, a new clinical syndrome is being defined on the basis of the molecular finding. In addition to the skull findings, some patients had abnormalities on radiographs of hands and feet, including thimble-like middle phalanges, coned epiphyses, and carpal and tarsal fusions. Brachydactyly was seen in some cases; none had clinically significant syndactyly or deviation of the great toe. Sensorineural hearing loss was present in some, and developmental delay was seen in a minority. While the radiological findings of hands and feet can be very helpful in diagnosing this syndrome, it is not in all cases clearly distinguishable on a clinical basis from other craniosynostosis syndromes. Therefore, this mutation should be tested for in patients with coronal synostosis.

Mutation detection in FGFR2 craniosynostosis syndromes

Five autosomal dominant craniosynostosis syndromes (Apert, Crouzon, Pfeiffer, Jackson-Weiss and Crouzon syndrome with acanthosis nigricans) result from mutations in FGFR genes. Fourteen unrelated patients with FGFR2-related craniosynostosis syndromes were screened for mutations in exons IIIa and IIIc of FGFR2. Eight of the nine mutations found have been reported, but one patient with Pfeiffer syndrome was found to have a novel G-to-C splice site mutation at-1 relative to the start of exon IIIc. Of those mutations previously reported, the mutation C1205G was unusual in that it was found in two related patients, one with clinical features of Pfeiffer syndrome and the other having mild Crouzon syndrome. This degree of phenotypic variability shows that the clinical features associated with a specific mutation do not necessarily breed true.

Clinicopathologic findings in congenital aneurysms of the great vessels

We describe the clinical, histopathologic, and angiographic findings in four children with congenital abnormalities of the great vessels of unknown cause, comprising either single or multiple arterial aneurysms, aortic/arterial dilatation, vessel tortuosity, or combinations of these abnormalities. Two children had early and severe respiratory distress due to aneurysmal compression of the trachea. All children had diffuse dilatation of several arteries, and two children also had tortuosity of multiple arteries. Progression of these abnormalities was clearly evident in one child, in whom diffuse vessel irregularity and tortuosity affected intra-abdominal, and intra and extra-cranial arteries. One child died at 5 years, while the other three have undergone successful surgical repair in the first 3 months of life and are now well, between age 2.5 and 7 years. The phenotype of each child appears unique but all have in common the rare finding of aneurysms of the aorta and main pulmonary artery. Congenital aortic aneurysms did not occur as an isolated finding in any of these children.

Characterisation of four novel fibrillin-1 (FBN1) mutations in Marfan syndrome

Forty-four percent of the fibrillin-1 gene (FBN1) from 19 unrelated families with Marfan syndrome was screened for putative mutations by single strand conformational polymorphism (SSCP) analysis. Four novel mutations were identified and characterised in five people, three with classical Marfan syndrome (two from one family, and one from an unrelated family), one with a more severe phenotype, and one with neonatal Marfan syndrome. The base substitutions G2113A, G2132A, T3163G, and G3458A result in amino acid substitutions A705T, C711Y, C1055G, and C1152Y, respectively. C711Y, C1055G, and C1152Y lead to replacement of a cysteine by another amino acid; the latter two occur within epidermal growth factor-like motifs in exon 25 and 27, respectively. The A705T mutation occurs at exon 16 adjacent to the GT splice site. The A705T and C711Y mutations, at exon 16 and 17, respectively, are the first documented in the second transforming growth factor-beta 1 binding protein-like motif of FBN1.

Detection of a megabase deletion in a patient with branchio-oto-renal syndrome (BOR) and tricho-rhino-phalangeal syndrome (TRPS): implications for mapping and cloning the BOR gene

Genetic linkage analysis has previously mapped the locus for the autosomal dominant disorder branchio-oto-renal syndrome (BOR) to the pericentric region of chromosome 8q. A YAC contig spanning the putative BOR region, from D8S543 to D8S541, was constructed and confirmed by sequence-tagged site content mapping using microsatellite markers and by DNA hybridization analysis. YACs spanning the BOR interval were used as fluorescence in situ hybridization probes on a cell line from a patient with BO and tricho-rhino-phalangeal syndrome I that involves a chromosome 8q rearrangement. In addition to the cytogenetically defined direct insertion of material from 8q13.3-q21.13 into 8q24.11, a previously unidentified deletion of just under one megabase was found in 8q13.3. These data narrowed the most likely location of the BOR gene to a region corresponding to the proximal two-thirds of YAC 869E10 between D8S543 and D8S279.

Prenatal exposure to phenytoin, facial development, and a possible role for vitamin K

Ten patients with maxillonasal hypoplasia (Binder "syndrome"), who were prenatally exposed to phenytoin (usually in combination with other anticonvulsants), were identified retrospectively. In addition to their facial anomalies, 6 of the patients were radiographed neonatally and showed punctate calcification, characteristic of chondrodysplasia punctata. Evidence is presented that the facial abnormalities seen in these children are due to anticonvulsant-induced vitamin K deficiency, causing abnormal development of the cartilaginous nasal septum. We propose that early vitamin K supplementation of at-risk pregnancies may prevent the development of maxillonasal hypoplasia, which in some patients is severely disfiguring and causes great emotional distress. Correction of this facial defect requires surgical and dental treatment over a long period of time.

Optimal polymerase chain reaction amplification for preimplantation diagnosis in cystic fibrosis (delta F508)

OBJECTIVE

To evaluate direct polymerase chain reaction amplification of mutation on single embryo cells for the routine preimplantation diagnosis of cystic fibrosis.

DESIGN

Direct polymerase chain reaction amplification of mutation was performed to identify the cystic fibrosis delta F508 mutation in human blood DNA, single lymphocytes, embryos, and embryo cells obtained by biopsy. Preimplantation diagnosis was performed for a couple who were heterozygous carriers of the delta F508 mutation.

SETTING

Laboratory for preimplantation diagnosis in a reproductive medicine unit.

MAIN OUTCOME MEASURE

Correct diagnosis of homozygous normal, heterozygous, and homozygous abnormal DNA of the cystic fibrosis delta F508 mutation.

RESULTS

45 blood samples (18 homozygous normal, 17 heterozygous, and 10 homozygous abnormal) and 204 single lymphocytes from known sources showed 100% amplification and were diagnosed correctly. 17 human embryos and 52 normal nucleated embryo cells obtained by single cell embryo biopsy also showed 100% amplification. After a miscarriage of the initial pregnancy (diagnosed at preimplantation to be homozygous normal) in the heterozygous carrier couple, fetal tissue was confirmed to be homozygous normal.

CONCLUSION

Direct polymerase chain reaction amplification of mutation is a simple, fast, reliable test for the common cystic fibrosis mutation (delta F508) in blood DNA and single cells and should be applicable to routine programmes of general screening, maternal blood examination, and preimplantation diagnosis.

Distinct skeletal abnormalities in four girls with Shprintzen-Goldberg syndrome

We describe 4 girls with Shprintzen-Goldberg syndrome. Skeletal abnormalities common to 3 of them include bowing of long bones (with a variable degree of progression over time), flare of the metaphyses, a large anterior fontanel with persistent patency into the second to fourth years of life, 13 pairs of ribs, distinct vertebral abnormalities which were absent neonatally but evolved by the second year of life, and progressive osteopenia. These abnormalities were generalized and, in one case, progressive over the first few years of life. Communicating hydrocephalus was present in all 4 cases. The eldest, an 11-year-old girl, had additional anomalies not reported previously in this syndrome, including intestinal malrotation, an anteriorly placed anus, and mild cerebral atrophy. This is the first detailed report of skeletal manifestations in this rare disorder of unknown cause. These cases, in conjunction with a review of the literature, suggest that skeletal abnormalities are common in Shprintzen-Goldberg syndrome.

The sensitivity of ultrasound and serum alpha-fetoprotein in population-based antenatal screening for neural tube defects. South Australia 1986-1991

OBJECTIVE

To determine the sensitivity of antenatal screening methods for neural tube defects in population-based screening in South Australia in 1986-1991, and whether ultrasound can replace serum alpha-fetoprotein screening in terms of achieving an equivalent level of sensitivity.

DESIGN AND SETTING

Ascertainment of all births and terminations of pregnancy with neural tube defects from multiple sources for 1986-1991 in South Australia. Serum and amniotic fluid alpha-fetoprotein results were obtained from the only laboratory performing the tests as a Statewide antenatal screening programme, and information on ultrasound screening from case notifications, hospital case records and medical practitioners who cared for the women.

SUBJECTS

All 243 births and terminations of pregnancy with neural tube defects in South Australia in 1986-1991.

MAIN OUTCOME MEASURES

The sensitivity of individual screening methods and of all methods used, particularly for spina bifida.

RESULTS

For pregnancies with neural tube defects screened by any method (serum alpha-fetoprotein, ultrasound or amniocentesis), 86% sensitivity was achieved. Ultrasound screening for anencephaly achieved 100% sensitivity even in low risk pregnancies, compared with 92% for serum alpha-fetoprotein. For spina bifida, the sensitivity of ultrasound screening increased with the level of risk in pregnancy: it was 60% in low risk pregnancies, which was equivalent to that of serum alpha-fetoprotein screening (64%); 89% in high risk pregnancies and 100% for women referred for confirmation of a suspected spina bifida by another ultrasonographer (chi 1(2) for trend = 23.49, P < 0.0001). Ultrasound screening in high risk pregnancies for spina bifida achieved higher sensitivity in teaching hospitals compared with other ultrasound services in the State (97% vs 65%), but sensitivity was equivalent for low risk pregnancies. It is estimated that, had the serum screening programme not been in place, the level of sensitivity achieved for spina bifida by ultrasound and amniocentesis would have been 62% compared with the actual situation of 76% with the programme in existence, a difference of nearly 15% (95% CI 2.5 to 26.7) (chi 1(2) = 5.45, P = 0.02).

CONCLUSIONS

Antenatal screening for neural tube defects in South Australia achieved a higher level of sensitivity with the maternal serum alpha-fetoprotein programme in place. We conclude that the serum screening programme should continue in South Australia pending a significant improvement in the sensitivity of routine ultrasound screening for spina bifida.

Localization of craniosynostosis Adelaide type to 4p16

Craniosynostosis Adelaide type is a rare autosomal dominant syndrome associated with digital abnormalities. Linkage mapping was carried out excluding allelism to Saethre-Chotzen syndrome at 7p21, craniosynostosis Boston type at 5q34-q35, Jackson-Weiss and Crouzon syndromes at 10q24-q25 and Pfeiffer syndrome mapping near 8cen. Exclusion mapping was extended to the entire genome until linkage to chromosome 4 was detected. A maximum two-point lod score of 6.2 (theta = 0.0) was obtained with D4S412. The gene responsible for craniosynostosis Adelaide type was localized to 4p16, telomeric to D4S394. This region contains two plausible candidate genes, the MSX1 (HOX7) homeobox gene and the FGFR3 fibroblast growth factor receptor gene.

Molecular dissection of a contiguous gene syndrome: localization of the genes involved in the Langer-Giedion syndrome

The Langer-Giedion syndrome (tricho-rhino-phalangeal syndrome type II, TRPS II) is characterized by craniofacial dysmorphism and skeletal abnormalities. It combines the clinical features of TRPS I and multiple cartilaginous exostoses (EXT). We have used YAC cloning, Southern blotting, PCR analysis, and fluorescence in situ hybridization to study chromosome 8 deletions, translocations, an inversion, and an insertion in patients with TRPS I, TRPS II or EXT. Our results indicate that the TRPS gene maps more than 1,000 kb proximal to the EXT1 gene and that both genes are affected in TRPS II. We conclude that TRPS II is not due to pleiotropic effects of mutations in a single gene, but that it is a true contiguous gene syndrome.

Umbilical cord ulceration in association with intestinal atresia in a child with deletion 13q and Hirschsprung's disease

The case is reported of a baby boy with an interstitial deletion of the long arm of chromosome 13 who, in addition to the described associations of Hirschsprung's disease and intestinal atresia, had umbilical cord ulceration resulting in massive intrapartum haemorrhage. This case provides support for the existence of a previously reported association between umbilical cord ulceration and intestinal atresia, and suggests that it is aetiologically heterogeneous.

Jackson-Weiss syndrome: clinical and radiological findings in a large kindred and exclusion of the gene from 7p21 and 5qter

We describe the clinical and radiological manifestations of the Jackson-Weiss syndrome (JWS) in a large South Australian kindred. Radiological abnormalities not previously described in the hands include coned epiphyses, distal and middle phalangeal hypoplasia, and carpal bone malsegmentation. New radiological findings in the feet include coned epiphyses, hallux valgus, phalangeal, tarso-navicular and calcaneonavicular fusions, and uniform absence of metatarsal fusions. Absence of linkage to eight markers along the short arm of chromosome 7 excluded allelism between JWS and Saethre-Chotzen syndrome at 7p21. No linkage was detected to D5S211, excluding allelism to another recently described cephalosyndactyly syndrome mapping to 5qter.

Discordance between direct and PHA-stimulated chromosome preparations from neonates

Four examples of discordance between karyotypes prepared from direct and PHA-stimulated neonatal blood samples are presented. The specimens were initially studied by direct methods to establish a neonatal karyotype rapidly. The patients are described and the significance of the findings is discussed.

Neurological involvement in Worth type endosteal hyperostosis: report of a family

We present the first Australian family known with autosomal dominant endosteal hyperostosis affecting a mother and her 2 children. Neurological involvement comprising chronic intracranial hypertension and cranial nerve palsies were found in the mother; computerised tomography and magnetic resonance imaging of the head demonstrated symmetrical sclerosis of the cranial vault, narrow internal auditory meati and canals, inferior herniation of the cerebellar tonsils into the foramen magnum, and encroachment of occipital bone into the foramen magnum posteriorly. This is the fifth report of significant neurologic involvement in this condition and supports the view that severe forms of endosteal hyperostosis are not confined to the autosomal recessive variant, as individuals with the autosomal dominant form may also show progression with neurological involvement in adulthood.

Polydactyly, campomelia, ambiguous genitalia, cystic dysplastic kidneys, and cerebral malformation in a fetus of consanguineous parents: a new multiple malformation syndrome, or a severe form of oral-facial-digital syndrome type IV?

We describe a 27-week fetus with occipitoschisis, polydactyly, campomelia, cleft palate, laryngeal dysplasia, ocular colobomata, hepatic fibrosis and intrahepatic cyst, ambiguous genitalia, cystic dysplastic kidneys, and brain malformation. This pattern of abnormalities appears unique. The differential diagnosis is discussed. The parents are first cousins, making autosomal recessive inheritance likely.

Prevalence of neural tube defects in South Australia, 1966-91: effectiveness and impact of prenatal diagnosis

OBJECTIVE

To determine trends in total prevalence of neural tube defects in South Australia during 1966-91, the impact of prenatal diagnosis on birth prevalence, and the effectiveness of prenatal screening for neural tube defects in 1986-91.

DESIGN

All births and terminations of pregnancy affected by neural tube defects and information on prenatal screening were ascertained from multiple sources including the South Australian perinatal and abortion statistics collections, birth defects register, and state maternal serum alpha fetoprotein screening programme.

SETTING

Southern Australia.

SUBJECTS

All 1058 births and terminations of pregnancy affected by neural tube defects in 1966-91.

MAIN OUTCOME MEASURES

Total prevalence and birth prevalence of individual and all neural tube defects. The proportion of screened cases detected prenatally.

RESULTS

Total prevalence of neural tube defects during 1966-91 was 2.01/1000 births with no upward or downward trend. However, birth prevalence fell significantly (by 5.1% a year), with an 84% reduction from 2.29/1000 births in 1966 to 0.35/1000 in 1991 (relative risk = 0.16, 95% confidence interval 0.07 to 0.34). The fall was 96% for anencephaly and 82% for spina bifida. 85% of defects, both open and closed, were detected before 28 weeks' gestation in women screened by serum alpha fetoprotein or mid-trimester ultrasonography, or both, in 1986-91 (99.0% for anencephaly and 75.7% for spina bifida).

CONCLUSIONS

While the total prevalence of neural tube defects in South Australia remained stable, prenatal diagnosis and termination of pregnancy resulted in an 84% fall in birth prevalence during 1966-91. Screening detected over four fifths of cases in 1986-91.

Congenital heart malformation in Yunis-Varón syndrome

We describe a male infant with Yunis-Varón syndrome who has tetralogy of Fallot. This appears to be the first case of Yunis-Varón syndrome associated with congenital heart malformation.

Direct molecular diagnosis of myotonic dystrophy

Myotonic dystrophy (DM) arises from an unstable trinucleotide (CTGn) repeat sequence within the DM locus at 19q13.3. Twenty-three myotonic dystrophy families containing 205 persons with no symptoms, minimal manifestations, classic DM or congenital DM were investigated to validate the application of the pM10M6 probe to direct molecular diagnosis. Affected family members had been diagnosed clinically and the unaffected family members had been assigned carrier probabilities close to either zero or 100%, using closely linked flanking markers. Southern analysis identified all 89 DM gene carriers as having expansions of the unstable element. PstI detected all small expansions of the repeat sequence as easily seen discrete bands; but large expansions were usually seen as diffuse smears, sometimes difficult to distinguish from lane background. EcoRI concentrated these diffuse smears, associated with somatic instability, into discrete bands which were easy to detect; but it did not resolve the smaller expansions present in 9 (10%) of the DM carriers. It is essential that PstI and EcoRI gels are run in parallel to detect all DM gene carriers. The extent of expansion of CTG correlated with age of onset and disease severity. Biopsies of various fetal tissues from two terminated pregnancies confirmed the diagnosis obtained by CVS and revealed no heterogeneity between tissues at this developmental stage. Further expansion occurred during the culture of CVS cells, indicating that direct prenatal diagnosis needs to be carried out on CVS tissue rather than on cultured cells. The intergenerational change of the repeat sequence from DM parent to DM offspring showed a significant parental sex difference for those parents with large expansions. Contraction of the unstable element was observed in the three males carrying the largest expansions and could explain why congenital DM is exclusively of maternal origin.

Hunter-McAlpine syndrome: report of a third family

A 9-year-old girl with craniosynostosis, facial dysmorphism, mental retardation, proportionate short stature and acral abnormalities is described, in whom both clinical and radiological features support a diagnosis of Hunter-McAlpine syndrome. Her mother is mildly affected, confirming previous evidence that this syndrome is dominantly inherited and shows considerable phenotypic variability within families.

Anthropometric measurements in the second trimester fetus

Normal anthropometric measurements, of accepted value for clinicians and pathologists in the assessment of the dysmorphic neonate, have not in the past been available for the second trimester fetus, in which dysmorphic features are often more subtle and objective measurements most needed. In order to establish these values 19 anthropometric measurements, comparable to those published for the larger fetus and neonate, were recorded at autopsy on each of 260 overtly normal non-macerate singleton fetuses between 13 and 26 weeks gestation. Regression lines for each parameter, and growth ratios of potential value for description and assessment of dysmorphic features, were derived. The sex ratio was 1.27 and as there was no statistically significant sex difference for any of the 19 measurements chosen, the data was subsequently pooled. There were linear correlations between gestational age and each growth parameter, all but three exceeding 0.90. The linear correlations between pairs of growth parameter were higher than the correlations between gestational age and individual growth parameters. This suggests that growth parameter pairs, expressed as a ratio, are less affected by errors in gestational age estimation. Ratios enabling the dysmorphologist to more objectively assess common observations such as abnormalities of head shape, relationship between limb and trunk length and gross proportional relationships between major body segments were derived. Collected measurements were compared with established ultrasound reference ranges. While reference ranges for biparietal diameter and head circumference showed close concordance with those derived from ultrasound measurements, the abdominal circumference was consistently lower than that measured by ultrasound possibly because of differing trunk positions in utero compared with after death. The graphs and ratios derived in this study can be rapidly applied to confirm visual impressions at clinical examination and at autopsy.

Hydrocephalus in Hajdu-Cheney syndrome

Images

Humeroradioulnar synostosis in a patient with lambdoid synostosis

We report on a patient with humeroradioulnar synostosis and lambdoid synostosis. The case differs from three previously described cases in minor details, but the upper limb abnormalities are strikingly similar.

The OEIS complex (omphalocele-exstrophy-imperforate anus-spinal defects): recurrence in sibs

The OEIS complex comprises a combination of defects including omphalocele, exstrophy of the cloaca, imperforate anus, and spinal defects. It may represent the most severe manifestation of a spectrum of birth defects, the exstrophy-epispadias sequence. The OEIS complex affects 1 in 200,000 to 400,000 pregnancies and is of unknown cause. The purpose of the current report is to document the occurrence of OEIS in sibs from separate pregnancies and suggest that some cases may have a genetic basis.

Molecular cytogenetic and clinical studies of 42 patients with marker chromosomes

The molecular cytogenetic characterization and clinical details of 20 patients with marker chromosomes are presented. These 20 patients, together with another 22 patients previously published, represent a cohort in which the chromosomal origin of the marker chromosomes was successfully determined in all but one case. Examination of the pooled data suggests that the satellited markers derived from chromosomes 14, 15 (when metacentric or submetacentric), those whose origin is either 13 or 21, and those small ring autosomal markers derived from both alphoid and satellite II or III pericentric heterochromatin of chromosomes 1, 9, 15, and 16 are all associated with a low risk of phenotypic abnormality. The markers identified as i(18p), ring chromosomes derived from various autosomes, and satellited markers derived from chromosome 22 are associated with a high risk of phenotypic abnormality. The phenotype of patients with acrocentric markers derived from chromosome 15 was equivocal, perhaps as a result of imprinting. Additional data are required to confirm these trends. The mild mental retardation and abnormal face of a patient with a small ring chromosome derived from chromosome 4 are described. Identification of patients with small rings originating from particular chromosomes may allow the recognition of new syndromes.

Use of linkage data obtained in single families: prenatal diagnosis of a new X-linked mental retardation syndrome

Prenatal diagnosis was requested by an obligate carrier of a new syndrome of X-linked mental retardation. There was close linkage between the disease gene and the hypervariable VNTR marker DXS255 with a lod score of 4.82 at o = 0 (90% support interval 0.00-0.12). When the request for prenatal diagnosis was made, additional family members were examined, resulting in an amended lod score of 6.71 at o = 0.0 (90% support interval 0.00-0.09). There were no informative flanking markers at the time of the request for prenatal diagnosis; hence it proceeded by 2 point linkage analysis. The fetus was female with a carrier risk in the interval of 91-100%. Given the limitations of the mapping data available for this disorder at the time of the request, the options of accepting or rejecting this as a case for prenatal diagnosis were carefully considered. Whilst prenatal diagnosis based on fetal sexing would be sufficient to prevent the birth of an affected child, the magnitude of the known two-point lod score between DXS255 and the disease gene provided a means for diagnosis with an accuracy between 91 and 100%.

Assignment of a gene (NEMI) for autosomal dominant nemaline myopathy to chromosome I

Nemaline myopathy (NEM) is a neuromuscular disorder characterized by the presence, in skeletal muscle, of nemaline rods composed at least in part of alpha-actinin. A candidate gene and linkage approach was used to localize the gene (NEM1) for an autosomal dominant form (MIM 161800) in one large kindred with 10 living affected family members. Markers on chromosome 19 that were linked to the central core disease gene, a marker at the complement 3 locus, and a marker on chromosome 1 at the alpha-actinin locus exclude these three candidate genes. The family was fully informative for APOA2, which is localized to 1q21-q23. NEM1 was assigned to chromosome 1 by close linkage for APOA2, which is localized to 1q21-q23. NEM1 was assigned to chromosome 1 by close linkage to APOA2, with a lod score of 3.8 at a recombination fraction of 0. Recombinants with NGFB (1p13) and AT3 (1q23-25.1) indicate that NEM1 lies between 1p13 and 1q25.1. In total, 47 loci were investigated on chromosomes 1, 2, 4, 5, 7-11, 14, 16, 17, and 19, with no indications of significant linkage other than to markers on chromosome 1.