Hand anomalies in fetal-hydantoin syndrome: from nail/phalangeal hypoplasia to unilateral acheiria

A case of acheiria

Congenital limb anomalies are rare. Acheiria is a congenital limb abnormality that presents as an absence of the hand and it is often diagnosed by prenatal ultrasonography. Herein we present a case of an 11-year-old female patient with acheiria. This case stresses on further studying the relationship between advanced pregnancy age, drugs or herb use during pregnancy and acheiria.

Syndromic disorders caused by gain-of-function variants in KCNH1, KCNK4, and KCNN3-a subgroup of K+ channelopathies

Decreased or increased activity of potassium channels caused by loss-of-function and gain-of-function (GOF) variants in the corresponding genes, respectively, underlies a broad spectrum of human disorders affecting the central nervous system, heart, kidney, and other organs. While the association of epilepsy and intellectual disability (ID) with variants affecting function in genes encoding potassium channels is well known, GOF missense variants in K⁺ channel encoding genes in individuals with syndromic developmental disorders have only recently been recognized. These syndromic phenotypes include Zimmermann–Laband and Temple–Baraitser syndromes, caused by dominant variants in KCNH1, FHEIG syndrome due to dominant variants in KCNK4, and the clinical picture associated with dominant variants in KCNN3. Here we review the presentation of these individuals, including five newly reported with variants in KCNH1 and three additional individuals with KCNN3 variants, all variants likely affecting function. There is notable overlap in the phenotypic findings of these syndromes associated with dominant KCNN3, KCNH1, and KCNK4 variants, sharing developmental delay and/or ID, coarse facial features, gingival enlargement, distal digital hypoplasia, and hypertrichosis. We suggest to combine the phenotypes and define a new subgroup of potassium channelopathies caused by increased K⁺ conductance, referred to as syndromic neurodevelopmental K⁺ channelopathies due to dominant variants in KCNH1, KCNK4, or KCNN3.

Deletions and de novo mutations of SOX11 are associated with a neurodevelopmental disorder with features of Coffin-Siris syndrome

BACKGROUND

SOX11 is a transcription factor proposed to play a role in brain development. The relevance of SOX11 to human developmental disorders was suggested by a recent report of SOX11 mutations in two patients with Coffin-Siris syndrome. Here we further investigate the role of SOX11 variants in neurodevelopmental disorders.

METHODS

We used array based comparative genomic hybridisation and trio exome sequencing to identify children with intellectual disability who have deletions or de novo point mutations disrupting SOX11. The pathogenicity of the SOX11 mutations was assessed using an in vitro gene expression reporter system. Loss-of-function experiments were performed in xenopus by knockdown of Sox11 expression.

RESULTS

We identified seven individuals with chromosome 2p25 deletions involving SOX11. Trio exome sequencing identified three de novo SOX11 variants, two missense (p.K50N; p.P120H) and one nonsense (p.C29*). The biological consequences of the missense mutations were assessed using an in vitro gene expression system. These individuals had microcephaly, developmental delay and shared dysmorphic features compatible with mild Coffin-Siris syndrome. To further investigate the function of SOX11, we knocked down the orthologous gene in xenopus. Morphants had significant reduction in head size compared with controls. This suggests that SOX11 loss of function can be associated with microcephaly.

CONCLUSIONS

We thus propose that SOX11 deletion or mutation can present with a Coffin-Siris phenotype.

The adverse effects of antiepileptic drugs in children

Efficacy of antiepileptic drugs (AEDs) are often equivalent, hence selection of an AED is often determined by the adverse effects (AEs). The development of neurocognitive AEs is almost inevitable with use of AEDs, especially in high-risk groups. Teratogenesis with major or minor malformations is of great concern during the first trimester of pregnancy, but an increasing body of information suggests that potential neurocognitive developmental delay may also occur with use of AEDs in the latter part of pregnancy. Decreased bone mineral density has been found in adults and children receiving both enzyme-inducing AEDs and valproate, an enzyme-inhibiting drug. AEDs may influence the lipid profile, body weight, reproductive, hormonal and other endocrine functions, and sleep architecture. There are age-specific AEs related to pharmacokinetic differences that have been highlighted in this review with emphasis on the pediatric population. A classification of AEs using different parameters is also included.

Pregnancy in women who have epilepsy

Ideal, comprehensive care of women who have epilepsy during the reproductive years must include effective preconceptional counseling and preparation. The importance of planned pregnancies with effective birth control should be emphasized, with consideration of the effects of the enzyme-inducing AEDs on lowering efficacy of hormonal contraceptive medications and the need for back-up barrier methods. Before pregnancy occurs, the patient's diagnosis and treatment regimen should be reassessed. Once the diagnosis of epilepsy is confirmed, it is important to verify if the individual patient continues to need medications and if she is taking the most appropriate AED to balance control of her seizures with teratogenic risks. For most women who have epilepsy, withdrawal of all AEDs before pregnancy is not a realistic option. A decision to undergo a trial while not taking AEDs before a planned pregnancy should be based on the same principles used for AED withdrawal in any person who has epilepsy. The taper should be completed at least 6 months before planned conception to provide some reassurance that seizures are not going to recur. If a woman who has epilepsy is in the more prevalent category of needing AEDs for seizure control, then monotherapy at the lowest effective dosage should be used. If large daily doses are needed, then frequent smaller doses or extended-release formulations may be helpful to avoid high peak levels. Some of the newest information about differential risks between AEDs also should be considered. The woman's AED regimen should be optimized and folate supplementation should begin before pregnancy. Given that 50% of pregnancies are unplanned in the United States, folate supplementation should be encouraged in all women of childbearing age who are taking any AED for any indication. Dosing recommendations vary from 0.4 mg/d to 5 mg/d. It is not uncommon for a physician to consider changing AED regimens when the patient first reports that she is pregnant. In many cases, she already is in or past the critical period of organogenesis (Table 3). If a woman who has epilepsy presents after conception and is taking a single AED that is effective, her medication usually should not be changed. Exposing the fetus to a second agent during a crossover period of AEDs only increases the teratogenic risk, and seizures are more likely to occur with any abrupt medication changes. If a woman is on polytherapy, it may be possible to switch to monotherapy safely. Seizure control remains an important goal during pregnancy. In particular, convulsive seizures place the mother and fetus at risk. Nonconvulsive seizures also may be harmful, especially if they involve falling or other forms of trauma. Monitoring serum AED levels during pregnancy can be helpful in optimizing seizure control. Prenatal screening can detect major malformations in the first and second trimesters. Vitamin K1 is given 10 mg/d orally during the last month of pregnancy followed by 1 mg intramuscularly or intravenously to the new-born. Although women who have epilepsy and women who are taking AEDs for other indications do have increased risks for maternal and fetal complications, these risks can be reduced considerably with effective preconceptional planning and careful management during pregnancy and the postpartum period.

The correlation of deficits in IQ with midface and digit hypoplasia in children exposed in utero to anticonvulsant drugs

OBJECTIVE

Children exposed during pregnancy to the anticonvulsant drugs phenytoin, phenobarbital, and carbamazepine as monotherapy and polytherapy have an increased frequency of midface and digit hypoplasia. Some children also have cognitive dysfunction. The hypothesis tested is that the anticonvulsant drug-exposed child with midface and digit hypoplasia is more likely to have cognitive dysfunction.

METHODS

Children exposed to anticonvulsant drugs (n = 80) were recruited for a follow-up evaluation, which included testing cognitive function and a physical examination for head size, height, and the presence of midface and digit hypoplasia. Microcephaly, midface and digit hypoplasia, and major malformations were correlated with full scale (FSI), performance (PIQ) and verbal (VIQ) intelligence.

RESULTS

The presence of the 3 anticonvulsant-exposed children with microcephaly had a deficit of 23.7 IQ points in FSI in comparison with the other children with a normal head size. Either midface or digit hypoplasia, after excluding the persons with microcephaly and with the Bonferroni correction, correlated significantly with deficits in VIQ (-12.7), PIQ (-10) and FSI (-12.8) IQ points ( P = .0061). There was no decrease in IQ in association with major malformations.

CONCLUSION

The presence of midface and digit hypoplasia in a child exposed to anticonvulsant drugs in pregnancy is an indication for a systematic developmental evaluation.

Multiple congenital anomalies associated with in utero exposure of phenytoin: Possible hypoxic ischemic mechanism?

BACKGROUND

The characteristics of the phenotype of the malformed phenytoin-exposed infant can help to clarify the mechanism of the drug's teratogenesis. One postulated mechanism is vascular disruption.

CASE

An infant who was exposed to phenytoin as monotherapy throughout pregnancy was born with the following abnormalities: midface hypoplasia, digit hypoplasia with syndactyly in the hands and feet, meningomyelocele, talipes equinovarus, and a long skin pedicle on the back. The mother was also exposed to cigarette smoking and alcohol during the pregnancy.

CONCLUSIONS

The malformations of the hands and feet, and the talipes deformity are potential effects of vascular disruption, a postulated fetal effect of both phenytoin and cigarette smoking. The mechanism of the teratogenicity of phenytoin may have included episodes of bradyarrhythmia in the fetus; however, no such episodes were documented.

Craniofacial skeletal deviations following in utero exposure to the anticonvulsant phenytoin: monotherapy and polytherapy

OBJECTIVE

To identify and quantify the craniofacial effects from prenatal exposure to phenytoin monotherapy and polytherapy using cephalometric, hand-wrist, and panoramic radiographs and to determine if such deviations persist with age.

DESIGN

Craniofacial structures of 28 anticonvulsant-exposed individuals were evaluated using 20 landmarks in lateral cephalometric radiographs and 19 landmarks in frontal cephalometric radiographs. Skeletal maturity was assessed using hand-wrist radiographs. Dental maturity and the presence of dental anomalies were evaluated using panoramic radiographs. Eleven individuals were re-evaluated 7 years later, on average, to determine the persistence of any measured deviations.

SETTING AND SAMPLE POPULATION

Department of Growth and Development, Harvard School of Dental Medicine and Massachusetts General Hospital. Patients were recruited from several sources.

OUTCOME MEASURE

The evaluated dimensions included linear, angular, and proportional measures.

RESULTS

The most common deviations were decreased height and length of the maxilla, decreased length of the posterior cranial base, length of the mandible, cranial width and level of the cribriform plate, and a decrease in the Wits Appraisal assessment. The deviations were more significant in the polytherapy-exposed individuals than in the monotherapyexposed individuals. These deviations, especially in the maxilla, persisted with age as revealed in a re-evaluation of 11 individuals.

CONCLUSION

The craniofacial skeletal findings among individuals exposed in utero to phenytoin monotherapy or phenytoin polytherapy, when considered in aggregate, suggest a mild pattern of maxillary hypoplasia that becomes more pronounced with age.

Teratogen-induced limb defects

Limb abnormalities are one of the most common and visible phenotypic effects of several human teratogens. The specific effects are different for most teratogens and include effects on limb morphogenesis (thalidomide, warfarin, phenytoin, valproic acid) and the effect of vascular disruption on a limb that had formed normally (misoprostol, chorionic villus sampling, and phenytoin). Either duplication (preaxial polydactyly of hands and feet) or deficiency (absence of thumb) is a common effect of thalidomide; no other human teratogen identified to date has this effect on the developing limb. Procedures during pregnancy, including chorionic villus sampling and dilation and curettage, produce defects of vascular disruption. For common exposures, such as alcohol and cocaine, it has been difficult to confirm objectively the exposure during embryogenesis and to ascribe specific limb defects that are produced. The molecular basis for the limb defects produced by the recognized human teratogens remains unknown.

Effects on toes from prenatal exposure to anticonvulsants

BACKGROUND

Changes in the distal phalanges of the fingers, including coned epiphyses and hypoplasia of the phalanges, are recognized teratogenic effects of the anticonvulsant drugs phenytoin and phenobarbital. We hypothesized that the frequency of these changes would also be increased in the toes of children exposed to these drugs in comparison to unexposed children.

METHODS

We report on the findings in an analysis of radiographs of the feet of 63 children exposed in utero to either phenytoin alone, phenobarbital alone or both drugs and 56 unexposed comparison children.

RESULTS

Only subtle changes were identified. The frequency of coned epiphyses and hypoplasia of phalanges of the toes was the same in both the anticonvulsant and unexposed children. Among the anticonvulsant-exposed children, however, there was a strong association between the presence of coned epiphyses in the feet and in the hands: all five children with coned epiphyses in the hands, as described previously in the same individuals by Lu et al. ([2000] Teratology 61:277-283) had coned epiphyses in their feet (P = 0.0012). Measurements showed a shortening of metatarsals in all three treatment groups, but this was significant only in the phenytoin monotherapy-exposed children.

CONCLUSIONS

Subtle changes are present in the phalanges and metatarsals of the feet of anticonvulsant-exposed children, but the overall frequency is much less than occurred in the hands of the same children. We conclude that the presence of either coned epiphyses or hypoplasia of the phalanges of the toes cannot be considered a distinctive feature of the teratogenicity of the anticonvulsant drugs phenytoin and phenobarbital.

Effect of prenatal exposure to anticonvulsant drugs on dermal ridge patterns of fingers

BACKGROUND

An altered frequency of specific dermal ridge patterns on fingertips, such as an increased number of arches, has been observed in children exposed in utero to anticonvulsants and other teratogens. Asymmetry of the distribution of dermal ridge patterns has been attributed to environmental exposures and genetic factors.

METHODS

We evaluated all of the dermal ridge patterns of 66 children who had been exposed to either the anticonvulsant phenytoin alone or phenytoin and phenobarbital. We determined the frequency of each pattern, concordance between the fingers on the left and right hands, sex differences and total ridge counts in the drug-exposed children and compared them to the findings in 716 unexposed comparison children. The frequency of each pattern was established in comparison to the most common type of pattern (ulnar loop), which showed that there were alterations in the frequency of arches, radial loops and whorls on specific fingers.

RESULTS

Eight (12.1%) of 66 children had three or more arch patterns, with all but one having been exposed to phenytoin and phenobarbital. Only one of these eight children was considered by the masked examiner to have fingernail hypoplasia. There was no evidence of asymmetry in the anticonvulsant-exposed children. There were minor differences in the distribution of total ridge count.

CONCLUSIONS

Subtle differences in several dermal ridge patterns, not just arch patterns, were present in anticonvulsant-exposed children, primarily in those exposed to polytherapy: phenytoin and phenobarbital.

Transposition of the great arteries and hypocalcemia in a patient with fetal hydantoin syndrome

We report a patient with fetal hydantoin syndrome (FHS) with associated d-transposition of the great arteries (d-TGA) and persistent hypocalcemia. d-TGA and hypocalcemia have each been individually reported once in association with FHS, but these patients were also prenatally exposed to phenobarbital. To our knowledge, this is the first report of these problems occurring after prenatal exposure to hydantoin alone. The combination of congenital heart disease and hypocalcemia in our patient raises the possibility of a hydantoin effect on neural crest migration.

The teratogenicity of anticonvulsant drugs

BACKGROUND

The frequency of major malformations, growth retardation, and hypoplasia of the midface and fingers, known as the anticonvulsant embryopathy, is increased in infants exposed to anticonvulsant drugs in utero. However, whether the abnormalities are caused by the maternal epilepsy itself or by exposure to anticonvulsant drugs is not known.

METHODS

We screened 128,049 pregnant women at delivery to identify three groups of infants: those exposed to anticonvulsant drugs, those unexposed to anticonvulsant drugs but with a maternal history of seizures, and those unexposed to anticonvulsant drugs with no maternal history of seizures (control group). The infants were examined systematically for the presence of major malformations, signs of hypoplasia of the midface and fingers, microcephaly, and small body size.

RESULTS

The combined frequency of anticonvulsant embryopathy was higher in 223 infants exposed to one anticonvulsant drug than in 508 control infants (20.6 percent vs. 8.5 percent; odds ratio, 2.8; 95 percent confidence interval, 1.1 to 9.7). The frequency was also higher in 93 infants exposed to two or more anticonvulsant drugs than in the controls (28.0 percent vs. 8.5 percent; odds ratio, 4.2; 95 percent confidence interval, 1.1 to 5.1). The 98 infants whose mothers had a history of epilepsy but took no anticonvulsant drugs during the pregnancy did not have a higher frequency of those abnormalities than the control infants.

CONCLUSIONS

A distinctive pattern of physical abnormalities in infants of mothers with epilepsy is associated with the use of anticonvulsant drugs during pregnancy, rather than with epilepsy itself.

Digit effects produced by prenatal exposure to antiepileptic drugs

The hypothesis tested was that digit anomalies among individuals exposed in utero to antiepileptic drugs (AED) are best identified by a systematic search, including radiographs and dermatoglyphics, rather than relying only on visual inspection. A systematic search was made for five types of digit abnormalities in 46 AED-exposed individuals ages 5-29 years in comparison with controls: visible anomalies, size of fingernails, dermal ridge patterns, length of metacarpals and phalanges, and qualitative changes in the distal phalanges. Among the AED-exposed, nail size was not decreased. However, there was a 10.8% frequency of digit anomalies, a 12% frequency of three or more arch patterns, and significant shortening and qualitative changes in the distal phalanges, all of which are consistent with the fetal effects of AED. Among the 42 individuals who underwent all evaluations, 14.3% had two or more of these abnormalities, most of which would not be identified by clinical inspection. This frequency is much higher in these AED-exposed individuals than in the general population. Radiographs in 13 individuals over a period of several years showed that the changes in the phalanges and metacarpals persisted.

A case of prenatal diagnosis of fetal hydantoin syndrome by ultrasound

Fetal hydantoin syndrome (FHS) is a set of disruptions occasionally present in fetuses exposed in utero to phenytoin or other anticonvulsants. Administration of phenytoin in early pregnancy may impair proper psychomotor performance expected for children's development. Several combined phenotypic markers delineate the syndrome, but the presence of single clinical signs is more common. There is controversy about the etiology of FHS. Associated disruptions may be related to a deficiency in a detoxifying enzyme (epoxide hydrolase), vascular problems, and/or factors not yet known. Genetic causes are believed to influence susceptibility to the drug. This text reports an unusual pattern of malformations detected in an ultrasound scan (gastroschisis, sacral meningomyelocele, and absence of the right lower limb) and in the anatomopathological study (left-side gastroschisis, sacral meningomyelocele, scoliosis, left clubfoot, absence of the right lower limb, and pectus carinatum) of a fetus whose mother took phenytoin. These defects may have been provoked by exposure to the drug during embryogenesis. In view of similar malformations observed in cases of prenatal exposure to cocaine, a recognized vasoconstrictor, it is suggested that vascular disruptions of hemodynamic origin constituted the event leading to some of the anomalies caused in the developing embryo. A complication of the chorionic villus sampling procedure, used for cytogenetic analysis, is another possibility.