Weaver Syndrome-Associated EZH2 Protein Variants Show Impaired Histone Methyltransferase Function In Vitro

Weaver syndrome (WS) is a rare congenital disorder characterized by generalized overgrowth, macrocephaly, specific facial features, accelerated bone age, intellectual disability, and susceptibility to cancers. De novo mutations in the enhancer of zeste homolog 2 (EZH2) have been shown to cause WS. EZH2 is a histone methyltransferase that acts as the catalytic agent of the polycomb‐repressive complex 2 (PRC2) to maintain gene repression via methylation of lysine 27 on histone H3 (H3K27). Functional studies investigating histone methyltransferase activity of mutant EZH2 from various cancers have been reported, whereas WS‐associated mutations remain poorly characterized. To investigate the role of EZH2 in WS, we performed functional studies using artificially assembled PRC2 complexes containing mutagenized human EZH2 that reflected the codon changes predicted from patients with WS. We found that WS‐associated amino acid alterations reduce the histone methyltransferase function of EZH2 in this in vitro assay. Our results support the hypothesis that WS is caused by constitutional mutations in EZH2 that alter the histone methyltransferase function of PRC2. However, histone methyltransferase activities of different EZH2 variants do not appear to correlate directly with the phenotypic variability between WS patients and individuals with a common c.553G>C (p.Asp185His) polymorphism in EZH2.

Sonographic 'molar tooth' sign in the diagnosis of Joubert syndrome

The characteristic imaging finding common to Joubert syndrome and related disorders is the 'molar tooth' sign. The prenatal diagnosis of Joubert syndrome using both ultrasound and fetal magnetic resonance imaging (MRI) in families with an affected child has been reported previously. We report two cases in which the molar tooth sign was identified by sonography at 26 + 4 weeks and at 20 + 6 weeks, respectively, prior to fetal MRI or genetic testing. In both cases the finding was subsequently confirmed on fetal MRI. As definitive prenatal genetic testing may not be conclusive in Joubert syndrome, the ability to identify the molar tooth sign sonographically before 24 weeks provides a valuable adjunct to prenatal diagnosis.

Renal-coloboma syndrome: prenatal detection and clinical spectrum in a large family

Renal-coloboma syndrome includes abnormalities in the urogenital and ocular systems as its primary manifestations, although it can be associated with abnormalities in other systems as well. This syndrome is caused by mutations in the PAX2 gene and is transmitted as an autosomal dominant trait. We report a family in which at least 7 members have manifestations of renal-coloboma syndrome, including two in whom renal disease was diagnosed prenatally by ultrasound examination. A pathogenic frame-shift mutation (619insG) was found in the PAX2 gene in affected family members, who show remarkable variability in both the ocular and renal manifestations of the syndrome.

Clinical and molecular findings in two patients with russell-silver syndrome and UPD7: comparison with non-UPD7 cases

The clinical presentation of prenatal and postnatal growth deficiency, triangular face, relative macrocephaly, and body asymmetry is frequently diagnosed as Russell-Silver syndrome (RSS). Maternal uniparental disomy (UPD) of chromosome 7 was reported previously in a small subset of individuals with RSS phenotype or primordial growth retardation. The primary purpose of this study was to identify RSS patients with UPD7 and determine whether or not they present phenotypic findings that distinguish them from RSS patients without UPD7. UPD7 testing was performed in 40 patients with unexplained growth retardation, including 21 patients with a diagnosis of RSS. In addition, a subset of patients was screened with markers spanning chromosome 7 to detect potential microdeletions or segmental uniparental disomy. Two of the RSS cases were identified to have maternal UPD7; no cases with deletion or partial UPD were detected. Together with previously published studies, UPD7 was identified in 11/120 (9%) of individuals with classical RSS phenotype. Our patients with UPD7 and those previously published had a classical RSS phenotype and were not clinically distinguishable from other children diagnosed with RSS.

Folate status, homocysteine metabolism, and methylene tetrahydrofolate reductase genotype in rural South African blacks with a history of pregnancy complicated by neural tube defects

The birth incidence of neural tube defects (NTDs) in South Africa is threefold to sixfold higher in rural compared with urban blacks. We investigated whether folate deficiency and aberrant homocysteine metabolism could explain the high NTD incidence in rural black populations. Plasma folate and total homocyst(e)ine (tHcy) concentrations were determined in apparently healthy rural black women (n = 107), rural black women with a history of pregnancy complicated by NTDs (n = 54), and urban blacks (n = 101). Methionine load tests were performed on the 54 women with a history of NTD-affected pregnancy and 54 controls matched for age and body mass. The presence of the 677C --> T mutation in the methylene tetrahydrofolate reductase (MTHFR) gene was investigated in both groups by a polymerase chain reaction (PCR) of genomic DNA and HinfI digestion of the PCR product. Apparently healthy urban black women (n = 101) had a lower (P < .001) plasma folate concentration compared with rural black women (n = 107). Women with a history of NTD-affected pregnancy did not differ significantly from controls with respect to plasma folate, fasting homocyst(e)ine, methionine, and the post-methionine load increase in plasma homocyst(e)ine. More than 50% of both of the latter groups had a post-methionine load increase in plasma tHcy less than the fifth percentile as observed in a healthy white control group. No homozygotes for the 677C --> T mutation in the MTHFR gene were found in black mothers with NTD-affected offspring or controls. It is concluded that black urbanization is characterized by a diminished folate status that is paradoxically associated with a lower NTD birth incidence. Homozygosity for the 677C --> T mutation in the gene coding for MTHFR does not constitute a genetic risk factor for NTDs in blacks. No aberrant homocysteine metabolism could be demonstrated in black women with NTD-affected pregnancies.

Renal tubular dysgenesis with calvarial hypoplasia: report of two additional cases and review

We report two cases of renal tubular dysgenesis (RTD) with calvarial hypoplasia and review the originally reported cases of RTD that came from our institution and published reports regarding the association of RTD and skull abnormalities. Although previously reported in association with RTD, calvarial hypoplasia is probably under-recognised. The cases reported here support the idea that the skull abnormalities observed in the inherited form of renal tubular dysgenesis are a common component of the disorder, as they are in the acquired form of RTD associated with maternal use of ACE inhibitors. Renewed attention to this clinical manifestation of RTD may be important in suggesting the diagnosis before death, providing more complete information to parents and physicians facing important management decisions and ensuring appropriate pathological examination postmortem.

Sutural exostoses, rib hyperostoses, craniosynostosis, mental retardation with focal fat deposition: Proteus syndrome?

We report on a 3-year-old boy with cartilaginous exostoses of the cranial sutures, rib hyperostosis, macrocephaly, metopic craniostenosis, epibulbar dermoid, hyperpigmented macules on the neck, focal fat deposition, and mild mental retardation with marked speech delay. Several of these manifestations were reported previously as an "unknown" by Thanos et al. [1977], with additional clinical information and a diagnosis of Proteus syndrome [Cohen, 1993].

Linkage analysis of two Canadian families segregating for X linked spondyloepiphyseal dysplasia

X linked spondyloepiphyseal dysplasia (SED) is caused by a growth defect of the vertebral bodies leading to characteristic changes in the vertebral bodies and a short trunk. The gene responsible for this disorder has previously been mapped to Xp22, with a maximum likelihood location between markers DXS16 and DXS92. We present linkage data using microsatellite markers on two Canadian X linked SED families, one of Norwegian descent and the other from Great Britain. In the Xp22 region, three recombination events have occurred in these families, two between markers DXS996 and DXS1043 and one between DXS999 and DXS989. One family shows a maximal lod score of 3.0 at theta = 0 with marker DXS1043 and the other family has a maximal lod score of 1.2 at theta = 0 with markers DXS1224 and DXS418. Both families therefore support the previously reported gene localisation.

Additional case of craniofacial and digital anomalies as reported by Harrod et al

In 1977 Harrod et al. [BD:OAS XIII (3B): 111-115] reported 2 brothers with an unusual syndrome of mental retardation, unusual facial appearance, large protruding ears, arachnodactyly, hypogenitalism, failure to thrive, and minor anomalies. We report on a 46-year-old man with striking resemblance to the children described by Harrod who also has secondary megacolon and varicose veins, suggesting a connective tissue disorder.

Multisite neural tube closure in humans

We present evidence for multisite NT closure in humans with representative examples of types of NTDs that would be expected if NT closure in humans is similar to experimental mice models. We determine that the majority of NTDs can be classified by the multisite closure model. Further evidence for multisite closure of the NT is apparent in previous epidemiological studies, recognized monogenic disorders, and environmental and teratogenic exposures. Previous reliance on the single-site closure model has resulted in grouping of anomalies, obscuring evidence for multisite NT closure, etiological heterogeneity, varying recurrence risks, and site-specific effects of environmental factors. The NTDs have been previously referred to as being multifactorial, due to multiple genes and environmental factors. Etiological heterogeneity has been demonstrated previously as well. Classification of NTDs by closure site will be beneficial in better defining etiologies and environmental susceptibilities. Similarly, it is apparent to us that genetic variations in closure sequence, rate, and location are most likely monogenic and result in affected embryos being more susceptible to specific environmental factors, such as the effect of folic acid deficiency. Individual closure sites are most likely under the control of specific embryonically expressed genes, whose monogenic nature may not be apparent postnatally. For the disorders such as Meckel-Gruber syndrome and Walker-Warburg syndrome, the monogenic etiology for NTDs in affected individuals is apparent because of associated malformations. There are three important implications of this study: The first is that monogenic mouse models will be helpful in investigating the pathogenesis of NTDs in humans. The homologies between the mouse and human genome may allow linkage studies to be done in some families who have recurrence of NTDs. Second, in order to have useful results from studies of NTDs, NT anomalies need to be accurately described, either by the classical nomenclature (eg, meroacranium) or by referring to the corresponding closure site involvement (eg, closure 2 defect). Special attention needs to be addressed to those NTDs that do not appear to fit into a discrete closure site (eg, midthoracic spina bifida cystica) or laterally displaced NTDs, since they may be due to other etiologies. With improved nutrition, particularly folic acid treatment, specific etiologies for the remaining NTDs may become more apparent. Finally, recurrence risks for NTDs may vary between families based on the closure site affected, and whether or not associated anomalies are present.

Mixed sclerosing bone dysplasia, small stature, seizure disorder, and mental retardation: a syndrome?

We present a 40-year-old man with mental retardation, short stature, minor anomalies, and seizures, who was found to have osteopoikilosis with melorheostosis (mixed sclerosing bone dysplasia, MSBD). Cytogenetic findings of a low level trisomy 8 mosaicism were not confirmed by fluorescence in situ hybridization (FISH) of fibroblast cells. To our knowledge, the association of MSBD and mental retardation has not been previously reported.

Deformations in infants of diabetic and control pregnancies

Severe and mild deformations in newborn infants of insulin dependent diabetic mothers (IDDMs) and control mothers were evaluated with respect to the types of anomalies and previously hypothesized constraint factors. Factors evaluated were gestational length, birth weight, corrected birth weight for gestation (weight ratio), maternal height and parity, and severe deformations. Newborn infants from 81 control and 133 insulin dependent diabetic pregnancies were recruited periconceptually as part of a larger study of diabetes in early pregnancy. Examinations were done at 48 to 72 hours of life by one examiner blinded to maternal status using a checklist of major and minor deformations and malformations. Mild deformations were found to be common and were present in 84% of newborn infants. Severe deformations occurred in three (1.4%) IDMs, with two of three newborn infants having major malformations involving the CNS and/or musculoskeletal system which affected fetal movement. There was no significant difference between IDMs and control newborn infants with respect to the number with deformations; however, fetal macrosomia was not present in study participants. Using the entire cohort, a significantly greater number of deformations were present in newborn infants with a gestation > 36 weeks (P < 0.001), birth weight > 3,000 g (P < 0.001), and weight ratio > or = 1.2 (P = 0.05). There was no significant association with primiparous mothers or women with a height < 165 cm and the presence of deformations. For gestational age and birth weight, mild deformations were apparent only after 33 weeks gestation (P << 0.001) and/or birth weights of 2.0 kg or more (P << 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Occurrence of chickenpox during pregnancy in women seropositive for varicella-zoster virus

In a group of 21 women counseled after exposure to chickenpox during pregnancy, 4 developed varicella despite initial studies showing that preinfection sera were varicella-zoster virus (VZV)-seropositive by fluorescent anti-membrane antibody, latex agglutination, ELISA, and VZV glycoprotein immunoblot assay. Further investigations showed that 2 of the 4 had low-titer (1/100), low-avidity, VZV-reactive IgG3 antibodies by ELISAs of preinfection sera. After chickenpox, these women developed primary-like serologic responses to VZV. Two women with high-titer (1/1600, 1/3200), high-avidity, IgG1 antibodies showed anamnestic serologic responses after reinfection. The criteria of protective VZV immunity remain ill-defined.

Clinical variability within Brachmann-de Lange syndrome: a proposed classification system

Seven patients, including two sibs, with the Brachmann-de Lange syndrome (BDLS) are presented as representative of the different types of BDLS in a proposed classification system. Type I ("classic") patients have the characteristic facial and skeletal changes of BDLS using the criteria in the diagnostic index of Preus and Rex. Type I is distinguished from the other subtypes by prenatal growth deficiency (< 2.5 S.D. below mean for gestation) becoming more severe postnatally (< 3.5 S.D. below the mean), moderate to profound psychomotor retardation, and major malformations which result in severe disability or death. Type II ("mild") BDLS patients have similar facial and minor skeletal abnormalities to those seen in type I; however, these changes may develop with time or may be partially expressed. Patients with type II BDLS are distinguished from those with other types by mild to borderline psychomotor retardation, less severe pre- and postnatal growth deficiency, and the absence of (or loss severe) major malformations. Behavioral problems can be a significant clinical problem in type II BDLS. Type III ("phenocopies") BDLS includes patients who have phenotypic manifestations of BDLS which are causally related to chromosomal aneuploidies or teratogenic exposures.

Partial duplication of 3q (q25.1-->q26.1) without the Brachmann-de Lange phenotype

Partial duplications of chromosome 3 have previously been reported to have phenotypic characteristics similar to Brachmann-de Lange syndrome (BDLS). We present the case of a 13-year-old girl with an apparent duplication in the 3q25.1-->q26.1 region but none of the manifestations commonly seen in BDLS. The chromosome 3 duplication was confirmed with a FISH painting probe of the involved region. These results suggest that the region critical for Brachmann-de Lange syndrome is not within the duplicated region of 3q25.1-->q26.1.

Recommendations on the use of folic acid supplementation to prevent the recurrence of neural tube defects. Clinical Teratology Committee, Canadian College of Medical Geneticists

OBJECTIVE

To prevent the recurrence of neural tube defects (NTDs) in families at increased risk of having offspring with NTDs with the use of periconceptional folic acid supplementation.

OPTIONS

Genetic counselling and prenatal diagnosis of NTDs.

OUTCOMES

NTDs cause stillbirth, neonatal death and severe disabilities. The cost for medical care and rehabilitation in the first 10 years of life of a child with spina bifida cystica was estimated to be $42,507 in 1987.

EVIDENCE

The authors reviewed the medical literature, communicated with investigators from key studies, reviewed policy recommendations from other organizations and drew on their own expertise. A recent multicentre randomized controlled trial showed that among women at high risk of having a child with an NTD those who received 4 mg/d of folic acid had 72% fewer cases of NTD-affected offspring than nonsupplemented women. Two previous intervention studies also demonstrated that folic acid supplementation was effective in reducing the rate of NTD recurrence. Several retrospective studies support this conclusion.

VALUES

Recommendations are the consensus of the Clinical Teratology Committee of the Canadian College of Medical Geneticists (CCMG) and have been approved by the CCMG Board. The committee believes that primary prevention of NTDs is preferable to treatment or to prenatal detection and abortion.

BENEFITS, HARMS AND COSTS

Folic acid supplementation should result in fewer NTDs among infants in Canada and ancillary savings in medical costs. The recommended dosage of folic acid is not known to be associated with adverse effects. Higher dosages of folic acid may make vitamin B12 deficiency difficult to diagnose and may alter seizure frequency in patients with epilepsy due to drug interactions with anticonvulsants.

RECOMMENDATIONS

A minimum dosage of folic acid of 0.8 mg/d, not to exceed 5.0 mg/d, is recommended along with a well-balanced, nutritious diet for all women who are at increased risk of having offspring with NTDs and who are planning a pregnancy or may become pregnant. Supplementation should begin before conception and continue for at least 10 to 12 weeks of pregnancy.

VALIDATION

These guidelines are similar to those of the Society of Obstetricians and Gynaecologists of Canada, the US Centers for Disease Control and Prevention and the Department of Health in Britain.

SPONSORS

These guidelines were developed by the CCMG Clinical Teratology Committee and endorsed by the Board of the CCMG. No funding for the development of these guidelines was obtained from any other sources.

Evidence for multi-site closure of the neural tube in humans

Four separate initiation sites for neural tube (NT) fusion have been demonstrated recently in mice and other experimental animals. We evaluated the question of whether the multisite model vs. the traditional single-site model of NT closure provided the best explanation for neural tube defects (NTDs) in humans. Evidence for segmental vs. continuous NT closure was obtained by review of our recent clinical cases of NTDs and previous medical literature. With the multi-site NT closure model, we find that the majority of NTDs can be explained by failure of fusion of one of the closures or their contiguous neuropores. We hypothesize that: Anencephaly results from failure of closure 2 for meroacranium and closures 2 and 4 for holoacranium. Spina-bifida cystica results from failure of rostral and/or caudal closure 1 fusion. Craniorachischisis results from failure of closures 2, 4, and 1. Closure 3 non-fusion is rare, presenting as a midfacial cleft extending from the upper lip through the frontal area ("facioschisis"). Frontal and parietal cephaloceles occur at the sites of the junctions of the cranial closures 3-2 and 2-4 (the prosencephalic and mesencephalic neuropores). Occipital cephaloceles result from incomplete membrane fusion of closure 4. In humans, the most caudal NT may have a 5th closure site involving L2 to S2. Closure below S2 is by secondary neurulation. Evidence for multi-site NT closure is apparent in clinical cases of NTDs, as well as in previous epidemiological studies, empiric recurrence risk studies, and pathological studies. Genetic variations of NT closures sites occur in mice and are evident in humans, e.g., familial NTDs with Sikh heritage (closure 4 and rostral 1), Meckel-Gruber syndrome (closure 4), and Walker-Warburg syndrome (2-4 neuropore, closure 4). Environmental and teratogenic exposures frequently affect specific closure sites, e.g., folate deficiency (closures 2, 4, and caudal 1) and valproic acid (closure 5 and canalization). Classification of NTDs by closure site is recommended for all studies of NTDs in humans.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of insulin-dependent diabetes on plasma lipoproteins in diabetic pregnancy

A reduction in total plasma cholesterol concentration has been reported in insulin-dependent diabetic (IDDM) pregnant women in early gestation. To determine if this reduction extends throughout gestation and which lipoprotein fractions may be responsible, we measured plasma triglyceride, cholesterol (C), high density lipoprotein cholesterol (HDL-C) and HDL2 and HDL3-C subfractions between 6 and 36 weeks' gestation in normal and IDDM women. Total plasma C was significantly lower in IDDM pregnant subjects between 20 and 36 weeks' gestation as compared to nondiabetic controls, while plasma triglyceride concentrations were not significantly different in this interval. Very low and low density lipoprotein (VLDL, LDL) C concentrations were not statistically significantly different from controls at any of the times studied, while HDL-C was lower throughout diabetic pregnancy as compared to controls, significantly so between 20 and 36 weeks' gestation. The lower HDL-C in IDDM women was associated with a significantly lower HDL3-C level. Plasma apoprotein A-I and A-II concentrations, markers of the HDL2 and HDL3 subclasses, respectively, were measured to corroborate the HDL subfraction changes. Apo A-I and A-II increased significantly between 12 and 28 weeks' gestation in control but not in diabetic pregnant subjects, consistent with a higher HDL3 in normal than in diabetic pregnant subjects. It appears that plasma triglyceride, VLDL and LDL-C, and HDL2-C concentrations are similar in IDDM and normal pregnancy, while total-C, HDL-C and HDL3-C and its associated apoproteins are lower than in normal subjects in late gestation. The mechanism of these changes and their significance for fetal growth and development deserve further study.

Trisomy 4 in a fetus with cyclopia and other anomalies

We report on an 18-week fetus with cyclopia, alobar holoprosencephaly, complex congenital heart defect, anal atresia, oligosyndactyly, cystic hygroma, and skeletal abnormalities with trisomy 4. Structural anomalies were detected on routine ultrasound of the pregnancy of a 17-year-old G3 P1 TAB1 woman with sickle cell trait. Trisomy 4 conceptuses usually miscarry in the first trimester. We are aware of no other reports of a fetus with trisomy 4 and cyclopia. Causal association of chromosome abnormalities and holoprosencephaly sequence may be more apparent in embryos and early fetuses than term fetuses because of poor viability of affected conceptuses.

Constriction bands and limb reduction defects in two newborns with fetal ultrasound evidence for vascular disruption

Most structural anomalies attributed to vascular disruption have been inferred, though not proven, to be the result of disruptive events in utero. We report on 2 pregnancies with ultrasound evidence of disruptive events resulting in terminal limb "reduction" defects with constriction bands and other anomalies. In the first patient a fetal ultrasound study at 12 weeks post-LMP demonstrated a monochorionic (MC) twin pregnancy with a nonviable co-twin and no evidence of amniotic bands. At birth, there was a left cleft lip and palate, and terminal limb "reduction" defects with ring constrictions of the left hand and both feet. In the second patient, a routine fetal ultrasound study at 18 weeks post-LMP identified a subhepatic cyst which subsequently resolved. Fetal ultrasound examination and neonatal computed tomography (CT) scan of the liver were consistent with a hepatic infarct due to emboli from the umbilical vein. At birth, patient 2 had acrosyndactyly of the left hand with ring constrictions of the digits and reduction of the left big toe. There was no evidence of abnormal amnion. Postnatal development has been normal in both cases. We present ultrasound evidence supporting the hypothesis that vascular disruption from death of a co-twin or from in utero embolic infarcts can cause: 1) terminal limb "reduction" defects and possibly cleft lip and palate; and 2) ring constrictions similar to those of "amniotic band disruption sequence" in the absence of an abnormal amnion. Serial pregnancy ultrasound studies are recommended for evaluation of the development of fetal structural anomalies following ultrasound evidence of a disruptive event in utero.

Craniosynostosis associated with partial duplication of 15q and deletion of 2q

We report on an infant with multiple congenital anomalies including complex craniosynostosis associated with an unbalanced karyotype, 46,XY,-2,+der(2),t(2;15)(q37;q26)pat. The previous report of a child with cloverleaf skull and partial duplication of 15q25----qter and the Man-on-Mouse Homology map suggests that a critical segment for synostosis of sutures may be in this region.

Trisomy 18 and a constitutional maternal translocation (2;18)

Parental chromosomes are usually not analyzed in cases of trisomy 18 because the extra 18 is assumed to have arisen through a meiotic nondisjunctional event. We report on a case of a trisomy 18 and a maternal translocation (2;18)(q34;q12).

Fatal combined defects in mitochondrial multienzyme complexes in two siblings

A female child suffering from intrauterine growth retardation was born by caesarean section at 32 weeks. In the immediate newborn period there was a metabolic acidosis but this resolved. Hypotonia, muscular weakness and poor respiratory effort were evident and the child died at 6 days of age. A previous male sibling had died at 3 months of age after similar symptoms with seizures and a dysmyelination disorder. Post-mortem examination of both children showed damage to the basal ganglia. Defects in the activities of the pyruvate dehydrogenase complex, cytochrome oxidase and succinate cytochrome c reductase were found in cultured skin fibroblasts. Similar defects were found in isolated muscle mitochondria but not in isolated liver mitochondria from the patient. Immunoblotting for cytochrome oxidase showed that the multienzyme complex was not assembled in muscle and skin fibroblast mitochondria, but was assembled in liver mitochondria. Similar results were obtained in cultured skin fibroblast mitochondria for complex I of the mitochondrial respiratory chain. This is the first occasion that multiple defects have been demonstrated both in tissue and in culture skin fibroblasts in mitochondrial respiratory chain complexes.

Early sonographic evaluation for fetal growth delay and congenital malformations in pregnancies complicated by insulin-requiring diabetes. National Institute of Child Health and Human Development Diabetes in Early Pregnancy Study

OBJECTIVE

It has been reported that early fetal growth retardation may be a useful marker for congenital malformations in diabetic pregnancies. To test this hypothesis, diabetic and nondiabetic women were sonographically evaluated during the first trimester.

RESEARCH DESIGN AND METHODS

Fetal crown-rump lengths were measured sonographically at least once during the first 15 wk of pregnancy in 329 nondiabetic and 312 diabetic women. Of these, 289 nondiabetic and 269 diabetic women had sonograms before 10 wk of gestation and 283 nondiabetic and 269 diabetic women had sonograms between 10 and 15 wk of gestation. Early fetal growth delay was defined as a sonographic gestational age of greater than or equal to 6 days less than menstrual gestational age.

RESULTS

The mean crown-rump lengths at 8 wk were 17.9 +/- 4.6 mm in the diabetic and 18.7 +/- 4.9 mm in the nondiabetic groups (P = 0.13). At 12 wk, the mean fetal crown-rump length was 58.5 +/- 8.8 mm for diabetic subjects and 60.6 +/- 8.7 mm for nondiabetic subjects (P = 0.04). Between 5 and 9 wk, 28 of 289 (9.7%) fetuses of nondiabetic subjects, 34 of 259 (13.1%) normal fetuses of diabetic subjects, and 2 of 10 (20%) malformed fetuses of diabetic subjects demonstrated growth delay (P = 0.31, normal vs. malformed diabetic). Between 10 and 15 wk of gestation, 28 of 283 (9.9%) fetuses of nondiabetic subjects, 32 of 256 (12.5%) normal fetuses of diabetic subjects, and 4 of 13 (30.8%) malformed fetuses of diabetic subjects demonstrated growth delay (P = 0.06, normal vs. malformed diabetic). Early fetal growth delay did not predict a reduced birth weight at term.

CONCLUSIONS

Among insulin-dependent diabetic subjects who were moderately well controlled at conception, statistically significant but mild early fetal growth delay was present but did not appear to be useful clinically in predicting congenital malformations. Recommendations that growth delay demonstrated on early ultrasound be used as a predictor of congenital malformation require careful reexamination.

Structural anomalies resulting from vascular disruption

A diverse yet distinctive group of disorders and structural anomalies result from vascular disruption of embryonic and fetal blood vessels. The extent of damage, timing in gestation, and the mechanism of vascular disruption all determine the nature of the resultant structural anomalies. The developing human remains susceptible throughout pregnancy to teratogenic agents and events that alter uterine, placental, and embryonic or fetal circulation.

New multiple congenital anomalies syndrome in a stillborn infant of consanguinous parents and a prediabetic pregnancy

We report on a term stillborn female infant with multiple congenital anomalies (MCA) which have not previously been reported as occurring together. The malformations include a first and second branchial arch sequence, ectopia cordis with congenital heart defect, caudal "regression" sequence with absent sacrum and hypoplastic right femur, ectrodactyly, left radial abnormality, islet cell hyperplasia, and skin lesions. The pregnancy was complicated by abdominal cramping with exercise, heavy vaginal bleeding, maternal obesity, and a normal screening glucose tolerance test at 6 months gestation. The infant was born to 20-year-old G3P1SAB2 Mexican-American parents who are first cousins. There was strong maternal family history of adult-onset diabetes. The malformations have some findings in common with those seen in infants of diabetic mothers. Structural defects similar to, but not inclusive of, those in our infant have been reported in 2 sibs born to a prediabetic mother with a first cousin marriage as well as in focal dermal hypoplasia. Parental consanguinity is suggestive of an autosomal recessive disorder. Alternatively, it may represent a combined multifactorial effect making the conceptus more sensitive to metabolic teratogens and thus placing it at increased risk for disruption of normal development.

Familial marker chromosome due to 3:1 disjunction of t(9;15) in a grandparent

An extra small chromosome detected in amniotic fluid was identified as the product of a translocation [46,XX,t(9;15)(p24;q11.2)]. This case is unusual in that individuals with the unbalanced karyotype resulting from a 3:1 disjunction are phenotypically normal.

In utero thrombosis and neonatal gangrene in an infant of a diabetic mother

We report an infant of a diabetic mother (IDM) with in utero brachial artery thrombosis and neonatal gangrene to illustrate that there may be an increased risk for arterial as well as venous thrombosis in IDMs. The diagnosis of brachial artery thrombosis was made by using Doppler sonography flow studies and was confirmed with autopsy. The postnatal period was complicated by aortic and mesenteric artery thrombosis, with subsequent necrotizing enterocolitis, renal infarction, and death. Gangrene of a limb presenting at birth is rare, with 32 individuals reported in the literature, including this patient. Twenty-two percent (7/32) of the infants with peripartum limb gangrene were IDMs. This implies a marked increase in arterial thrombosis in IDMs over the general population. Changes in coagulation factors have been reported in newborn IDMs with poor control of maternal diabetes. Increased clotting and decreased fibrinolysis found in diabetics may lead to arterial thrombosis in IDMs in utero and postnatally. Use of anticoagulants in at-risk infants should be considered to prevent further thrombosis postnatally. Additionally, IDMs may be at increased risk for thrombotic complications from umbilical artery catheter. In utero thrombosis of the brachial artery may be one mechanism which leads to limb reduction defects in IDMs.

Limb-body wall complex: II. Limb and spine defects

Limb defects from 25 fetuses with limb-body wall (LBW) complex were evaluated to determine the mechanism of limb damage. The limb defects could be divided into 3 pathogenetic groups: (1) secondary to disruption of embryonic vessels and surrounding tissue (84%), (2) secondary to amniotic bands or adhesions (16%), and (3) deformation versus hemorrhage (44% with club feet), with some fetuses having more than one pathogenetic mechanism causing limb defects. The hypothesis that the majority of limb defects resulted from disruption of embryonic vessels was supported by the following findings: 96% of the LBW complex fetuses had limb defects; the lower limbs were at greater risk of damage than the upper limbs (28% rt arm, 52% lt arm, 60% rt leg, 72% lt leg); there was a distal to proximal progression of limb damage in 92% of the fetuses; statistical analysis of comparing the location of the most severe limb defect and the body wall defect did not find concordance between the side (p = 1.0) and the region (p = 0.18) of the body wall defect; and limb defects found in the human specimens were similar to those produced in experimental animals following disruption of embryonic vessels at a corresponding gestation. In the specimens with amniotic band related limb defects (16%), the most likely pathogenesis is mechanical rupture through the amnion in the presence of a persistent extraembryonic coelom or from adhesion of the amnion to necrotic embryonic tissue after the initial disruptive event. Club feet were present in 44% and may be due either to disruption of embryonic vessels or to deformation. Further studies are needed to resolve this question.

Limb body wall complex: I. Pathogenesis

Twenty-five fetuses with limb body wall complex (LBW complex) were evaluated. The diagnosis was based on two out of three of the following: exencephaly/encephalocele with facial clefts; thoraco- and/or abdominoschisis; and limb defect. Ninety-five percent (24/25) of the fetuses had associated internal structural defects. In 72% (18/25) the internal defects have been recognized as being secondary to vascular disruption. Concordance was not found between the side and location of the body wall defect versus the limb, internal, and cranial defects. In 85% there was evidence for persistence of the extraembryonic coelom by examination of the placenta. In this same group (85%) there was persistence of the ectodermal-amnion margin, with the amnion being continuous with the skin of the body wall defect. In 40% (10/25) there were tags and amniotic adhesions at other sites. There was no difference in the types or incidence of internal defects between those with and those without amniotic bands. The abnormalities in this collection and experimental animal models support vascular disruption during 4-6 weeks' gestation as an etiology for LBW complex. There is disruption and loss of existing tissues, persistence of embryonic structures, and secondary malformations. Persistence of the extraembryonic coelom may lead to the typical amniotic tags, ring constrictions, and adhesions seen in some specimens.

Lipoprotein metabolism in pregnancy, fat transport to the fetus, and the effects of diabetes

The objective of this paper is to review the extent and mechanisms of lipoprotein alterations in pregnancy, present new data relating to placental lipid transport in normal humans and diabetic animals and consider possible effects on fetal growth and development in normal and diabetic pregnancy. The concentration of all lipoprotein fractions increases during pregnancy. VLDL cholesterol and triglyceride increase 2.5-fold over prepregnancy levels and LDL cholesterol increases 1.6-fold, all with peak levels at term. HDL cholesterol is maximally increased in midgestation by 1.45-fold and subsequently declines to 1.15-fold at term. The mechanisms of these lipoprotein changes have not been studied in humans but the hypertriglyceridemia in animal models is related to enhanced VLDL entry into the circulation. In addition, diminished adipose tissue lipoprotein lipase (LPL) activity in late gestation may cause a rerouting of triglyceride fatty acids to other tissues such as muscle and uterus for oxidation, rather than storage, since triglyceride transport is not reduced in pregnancy. All of these changes appear to be sex hormone mediated. In diabetic pregnancies, the available data indicate that triglyceride concentrations are increased and HDL cholesterol concentrations are decreased with reference to lipoproteins in nondiabetic pregnant women. Previously unpublished data show that a transplacental FFA gradient exists across the umbilical circulation in the direction of the fetus and is proportional to the maternal FFA concentration. No gradient is seen for triglyceride or total plasma cholesterol. However, transport of unmeasured amounts of triglyceride fatty acids may still occur via placental LPL and be exaggerated in diabetes where LPL declines in adipose tissue but not in placenta. The mechanism of transplacental cholesterol transport remains to be defined. Preliminary studies suggest that it depends on HDL as well as LDL since both can provide cholesterol for placental progesterone synthesis. In addition, fetal weight and length are associated with maternal apoproteins A-I and A-II, both major apoproteins of HDL. By lowering HDL in pregnancy, diabetes mellitus could negatively affect these relationships. In conclusion, sex hormone mediated modifications of lipoprotein physiology are described in pregnancy which may enhance triglyceride fatty acid transport to muscle for oxidation and LDL and HDL cholesterol delivery to growing maternal and fetal tissues, a process that diabetes could globally disrupt.

Ectopia cordis thoracalis with craniofacial defects resulting from early amnion rupture

A 33-week-gestation fetus was evaluated as having ectopia cordis thoracalis, midline sternal cleft, frontonasal dysgenesis, a midfacial cleft, and amniotic bands. Fibrous bands were attached to the apex of the heart, face, and the brain. There were no associated limb defects or scoliosis. The findings in this fetus and those in the literature suggest that acute amnion rupture in the third week of gestation may be the cause of these defects. Mechanical teratogenesis by tissue bands adherent to the heart may lead to ectopia cordis. The changes seen in the thorax, face, and brain suggest pressure necrosis, incomplete morphogenesis, tearing and tethering by amnion, and compression as a cause for these defects. A spectrum of defects is found following amnion rupture with the abnormalities being dependent upon the timing of the event. Ectopia cordis with amniotic bands appears to have an etiology distinct from isolated ectopia cordis. This suggests several different etiologies for ectopia cordis.

Noonan phenotype associated with neurofibromatosis

We report on four patients with neurofibromatosis and manifestations of Noonan syndrome including short stature, ptosis, "midface hypoplasia," apparently short webbed neck, learning disabilities, and weakness. No family history of neurofibromatosis was present in any case. Average paternal and maternal age at birth was 37 and 28 years, respectively, suggestive of a new mutation. The presence of a distinct phenotype and hypotonia in these patients with neurofibromatosis is suggestive of a new separate disorder.

Vascular pathogenesis of transverse limb reduction defects

Evaluation of four patients with unilateral transverse limb reduction defects indicates that some instances of this structural defect may be the result of an in utero vascular accident. Three of the four patients had microscopic evidence of fetal vascular occlusive disease on multiple sections of the placenta, suggesting that occlusion of the brachial artery was secondary to embolization from the placental vascular thrombi. The fourth, a 116 mm crown-rump long fetus, had a massive thrombus occluding the brachial artery, which was felt secondary to hypovolemia and hypoperfusion associated with fetal blood loss during placental abruption. Recognition of the disruptive vascular pathogenesis of some cases of unilateral transverse limb reduction defects explains their negligible recurrence risk. In such cases attention should be focused on careful gross and, microscopic evaluation of the placenta.

Vascular pathogenesis of limb defects. I. Radial artery anatomy in radial aplasia

Twelve human fetuses with radial aplasia were dissected to evaluate the vasculature of the arm. Three types of vascular patterns were found. In type I there was a single midline superficial vessel with no radial or ulnar artery. This pattern occurred in four perfused twins (acardia) with twins reversed arterial perfusion sequence, one fetus with clinical trisomy 18, and one with an unknown disorder with multiple field defects. In type II there was absence of the radial artery with or without persistence of the embryonic median artery; the other vessels were normal. This pattern was seen in three fetuses with unknown disorders associated with multiple malformations. In type III the radial artery was present but had an abnormal course. This pattern was found in three fetuses with thrombocytopenia-absent radius syndrome. From these dissections and the results of animal experiments on the embryology of the vasculature, the following conclusions can be drawn. Vasculogenesis precedes differentiation of mesenchyme into muscle and bone. The embryonic capillary net determines the adult vascular anatomy of the limb. Failure to form, malformations, or disruption of the capillary net results in anomalies of the adult vasculature and may lead to musculoskeletal defects. Failure to chondrogenesis does not disturb the capillary net, and normal arteries will develop. Absence of the radial artery found in association with radial aplasia implies that there was abnormal vasculogenesis or disruption of developing vessels, or both. Either can lead to this congenital musculoskeletal defect.

Intrinsic auricular muscles and auricular form

Plical folding of the cartilagenous ear plate is largely determined by the insertions of four extrinsic and seven intrinsic auricular muscles. Dissection of ten external auricles from anencephalic fetuses of six or more months' gestation was done. The transversus and obliquus auricular muscles found in association with the antihelical fold were evaluated. Four auricles were of normal form and had the transversus and obliquus auricular muscles with typical insertions in the cartilage. Six of the ten auricles had a simplified form, with no antihelical folding in five and minimal development in one. Fibers from neither the transversus nor the obliquus auricular muscles were identified in these six ears. The results of these dissections strongly suggest that antihelical folding is determined by the presence of functioning transversus and obliquus auriculae muscles. Similarly it is proposed that normal folding of the auricular cartilage is dependent on the presence of functioning auricular muscles. In evaluation of the child with absence of normal ear form, these findings suggest that the unusual shape is due to abnormal placement and/or function of the intrinsic and extrinsic auricular muscles. These changes may be a subtle sign of neuromuscular weakness, abnormal muscle insertion or absence of muscle.