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

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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.