Prenatal ultrasonographic diagnosis of osteogenesis imperfecta

Association of Antenatal Evaluations with Postmortem and Genetic Findings in the Series of Fetal Osteogenesis Imperfecta

INTRODUCTION

Counseling osteogenesis imperfecta (OI) pregnancies is challenging due to the wide range of onsets and clinical severities, from perinatal lethality to milder forms detected later in life.

METHODS

Thirty-eight individuals from 36 families were diagnosed with OI through prenatal ultrasonography and/or postmortem clinical and radiographic findings. Genetic analysis was conducted on 26 genes associated with OI in these subjects that emerged over the past 20 years; while some genes were examined progressively, all 26 genes were examined in the group where no pathogenic variations were detected.

RESULTS

Prenatal and postnatal observations both consistently showed short limbs in 97%, followed by bowing of the long bones in 89%. Among 32 evaluated cases, all exhibited cranial hypomineralization. Fractures were found in 29 (76%) cases, with multiple bones involved in 18 of them. Genetic associations were disclosed in 27 families with 22 (81%) autosomal dominant and five (19%) autosomal recessive forms, revealing 25 variants in six genes (COL1A1, COL1A2, CREB3L1, P3H1, FKBP10, and IFITM5), including nine novels. Postmortem radiological examination showed variability in intrafamily expression of CREBL3- and P3H1-related OI.

CONCLUSION

Prenatal diagnosis for distinguishing OI and its subtypes relies on factors such as family history, timing, ultrasound, genetics, and postmortem evaluation.

First-trimester screening

Screening for fetal chromosome abnormalities, particularly for trisomy 21, has made dramatic advances. Better screening demonstrates that "high-risk" patients--particularly over age 35--can have lower risk of defects than younger unscreened women. This has caused reduction of amniocentesis for older patients and made screening available for younger patients who have the universal 2% to 3% risk. This means lower procedural-related losses of normal fetuses, and better resource allocation. The trend toward first-trimester detection of structural defects continues; a normal survey is reassuring and helps exclude major defects. Based on screening results, patients can be triaged into early follow-up and possible amniocentesis as 14 to 16 weeks, or a later detailed anatomic survey at 18 to 20 weeks.

[Lethal osteogenesis imperfecta. Prenatal diagnosis]

INTRODUCTION

Osteogenesis imparfecta (OI) comprises a group of disorders principally affecting type I collagen, which result in increased bone fragility. Lethal forms are rare and are characterised by micromelia with malformation of the limbs.

CASE REPORT

A prenatal diagnosis of lethal OI was made by ultrasonography at 18 weeks of gestation and therapeutic abortion was indicated.

COMMENTS

Molecular biology and genetic studies offer new possibilities of prenatal diagnosis, but ultrasonography remains the investigation of choice. It confirms the diagnosis by revealing an increase in bone transparency.

Prenatal diagnosis of isolated femoral bent bone skeletal dysplasia: problems in differential diagnosis and genetic counseling

Severe localized and symmetric bowing of the femora, in the absence of other significant skeletal or nonskeletal abnormalities, is a rare prenatal ultrasound finding. A 38-year-old woman was referred at 19 weeks gestation and ultrasound of the fetus showed severe shortening, and marked symmetric bowing of the femora. A provisional diagnosis of kyphomelic dysplasia (KD) was made. The patient elected termination of pregnancy and post mortem assessments were most consistent with kyphomelic dysplasia. KD is bent-bone skeletal dysplasia that, in contrast to campomelic dysplasia, involves principally the femora with relative sparing of the remainder of the skeleton. KD can be difficult to distinguish, particularly from symmetric cases of femoral hypoplasia unusual facies syndrome (FH-UFS), and few prenatal diagnoses have been reported. Because KD is thought to an be autosomal recessive disorder, the possibility that definitive diagnosis may not be possible prenatally, and even by postmortem assessment in cases choosing to abort, is an important counseling consideration.

Congenital anomalies: a 25-year overview

Expansion of the discipline of hand surgery and heightened interest in congenital problems have resulted in major advances in the treatment of congenital hand anomalies over the past 25 years. Increased experience with congenital anomalies of the hand has expanded the hand surgeon's knowledge of patterns and relationships between different anomalies resulting in new methods of classification and more logical approaches to treatment. The principles of treatment of the more common anomalies, such as syndactyly, established by prior generations of hand surgeons have been refined in details of technique. New technologies, such as distraction lengthening and free vascularized transfers, have allowed the surgeon to treat new problems and old problems in new ways. In spite of our successes, much remains to challenge hand surgeons in this new millennium, especially in the construction of joints and the expanding field of fetal surgery.

Ultrasonographic prediction of fetal outcome in suspected skeletal dysplasias with use of the femur length-to-abdominal circumference ratio

OBJECTIVE

Our purpose was to determine whether the femur length-to-abdominal circumference ratio can be used antenatally to predict a lethal skeletal dysplasia.

STUDY DESIGN

All obstetric sonograms performed from January 1990 to October 1995 were reviewed (44,020 studies) to find those scans suggestive of a skeletal dysplasia. Thirty patients were identified. The femur length/abdominal circumference ratio was then calculated from each patient's initial and subsequent sonograms. Birth outcomes were obtained on the 27 patients who elected to continue their pregnancies.

RESULTS

All fetuses with a lethal skeletal dysplasia (n = 12) had a ratio <0.16. The fetuses with a nonlethal dysplasia (n = 8) had ratios between 0.134 and 0.193, with only 1 fetus with a ratio <0.16. All fetuses with no evidence of a skeletal dysplasia after birth (n = 7) had femur length/abdominal circumference ratios >0.18. The 1 fetus with a ratio <0.16 who survived the neonatal period had extreme bowing and demonstrates the limitation of the ratio when bowing is present.

CONCLUSIONS

A stillbirth or neonatal death occurred in 12 of 13 patients with a femur length/abdominal circumference ratio <0.16, independent of gestational age. Conversely, no fetus with a ratio >0.16 was found to have a lethal skeletal dysplasia. This information may be useful in counseling women when ultrasonography suggests the diagnosis of a skeletal dysplasia.

Prenatal diagnosis of osteogenesis imperfecta type II

OBJECTIVE

To characterize the prenatal sonographic features of osteogenesis imperfecta (OI) type II.

DESIGN

Descriptive (case series).

SETTING

Department of Obstetrics and Gynecology, Faculty of Medicine, Maharaj Nakorn Chiang Mai Hospital, Chiang Mai University.

SUBJECTS

Six fetuses with prenatal diagnosis of OI were evaluated.

RESULTS

Six fetuses were prenatally diagnosed as OI type II in five mothers without familial history of the disease. One mother had two consecutive pregnancies complicated with this condition. The first five cases were classified as OI type IIA, while the last one was OI type IIB. All of subtype A exhibited typical triad of bone shortening, diffuse hypomineralization and multiple fractures of long bones including beaded ribs whereas the subtype B showed shortening of only femurs, normal bone echodensity and isolated fractures of long bones. The postnatal radiography and autopsy confirmed the prenatal diagnosis in all cases. Other findings may occasionally be found, including polyhydramnios, oligohydramnios, hydrop fetalis and small for gestational age.

CONCLUSION

The triad of bone shortening, decreased bone density and numerous fractures including beaded ribs permits a confident diagnosis of OI type IIA. Furthermore, sonographic features may differentiate the subtype of OI type II, depending on degree of bone shortening and echodensity.

Prenatal diagnosis of osteochondrodysplasias in high risk pregnancy

We collected data on 39 prenatally diagnosed osteochondrodysplasias. We detected 30 (76.9%) cases in the first and second trimesters, including 18 (46.2%) with two twins before the 24th week of gestation. Of 39 cases 11 (28.2%) had osteogenesis imperfecta (OI) type II. Verification of the prenatal diagnosis was attempted in 26 cases on the basis of the data obtained from ultrasonographs, radiographs, external examination, and autopsy protocols. The prenatal diagnosis was confirmed in 19 (73%) fetuses. In 13 cases verification was not possible because one or several investigations could not be performed. Counselling followed all identified cases with osteochondrodysplasia. We present the pedigree of two families indicating the possibility of early prenatal diagnosis of achondrogenesis type I and metatropic dysplasia. We propose indications for ultrasonographic anatomical screening with subsequent phenotype analysis in high risk pregnancy to provide for the prenatal detection of malformations and hereditary diseases.

Antenatal diagnosis of short-limb dwarfism: sonographic approach

Based on the findings in 12 patients with skeletal dysplasia diagnosed antenatally, the authors propose a tailored approach to the evaluation of foetuses with shortened long bones, depending on the time of discovery, the degree of shortening and the associated findings. During the second trimester, a very short femur [2 standard deviations (SD) - 5 mm and less] most probably corresponds to a bone dysplasia, although the differential diagnosis is mainly early intra-uterine growth retardation, and the foetal skeleton should be surveyed completely in order to find supplementary features suggestive of dwarfism. Anomalies of long bones in their shape, thickness or contour, or spinal ossification disorders or undermineralisation (best evaluated at the level of calvarial bones) are most helpful in determining the type of dysplasia. A short femur (between 2 SD and 2 SD - 4 mm) may indicate growth retardation, a chromosomal anomaly or dwarfism. Follow-up examinations are mandatory in order to differentiate between them. During the third trimester a very short femur may indicate a bone dysplasia and the work-up should be the same as in the second trimester. A short femur may correspond to dwarfism of late development, a growth-retarded foetus or constitutional shortness. Various ratios, especially that of the femur/foot, are helpful in differentiating between them. In case of previous family history, a short or very short femur usually indicates recurrence of the dwarfism. In all cases of antenatal diagnosis, confirmation of the sonographic findings should be obtained either by foetal or neonatal radiographs. The approach proposed by the authors should provide sufficient information to counsel the family not only for the ongoing pregnancy but also for subsequent ones.

Transvaginal ultrasonography at early pregnancy cannot be used alone for targeted organ ultrasonographic examination in a high-risk population

OBJECTIVE

A study was performed to evaluate whether early second-trimester (13 to 16 weeks) transvaginal scan can be used alone for structure evaluation of the fetus or whether it should be followed by a transabdominal scan performed at 18 to 20 weeks of gestation.

STUDY DESIGN

A total of 536 pregnant women at high risk for birth defects were examined by transvaginal ultrasonography at 13 to 16 weeks' gestation. This was followed by a transabdominal scan at 18 to 20 weeks of pregnancy. Aborted specimens were examined by a pediatric pathologist in terminated pregnancies, and newborn babies were examined by a pediatrician to detect congenital anomalies.

RESULTS

Transvaginal ultrasonography performed at 13 to 16 weeks' gestation identified 42 structural anomalies. Of these, 24 pregnancies were terminated and one fetus died. The other 17 fetuses and the rest of the population underwent a second transabdominal survey at 18 to 20 weeks' gestation, which identified eight structural anomalies that were not diagnosed by the previous examination. In five cases the diagnosed anomaly disappeared. Together, the scans brought about the detection of 41 of 46 abnormal fetuses (89%).

CONCLUSIONS

Because a significant number of birth defects (17.4%) was not detected by early second-trimester vaginal scan, we recommend that whenever early transvaginal ultrasonographic examination is performed it should be followed by a transabdominal scan at the most advanced stage of pregnancy at which an abortion is still feasible.

Early prenatal ultrasonographic diagnosis of osteogenesis imperfecta: a case report

A case of lethal osteogenesis imperfecta detected at 14 weeks' gestation by transvaginal ultrasonography is described. The prenatal diagnosis of limb-shortening deformities caused by fractures and their repair is discussed.

First-trimester prenatal diagnosis of osteogenesis imperfecta type II by DNA analysis and sonography

Osteogenesis imperfecta type II was diagnosed prenatally by analysis of DNA obtained from chorionic villus sampling (CVS) performed at 12 weeks of gestation in a woman who previously had had an affected child. The father had been shown to be mosaic for a mutation in the gene (COL1A2) which encodes the alpha 2(I) chain of type I collagen. An affected fetus was predicted by detection of the mutation in amplified chorionic villus genomic DNA. Ultrasound examination at 13 weeks 4 days demonstrated femoral deformity and virtual absence of calvarial mineralization. In pregnancies at risk for osteogenesis imperfecta type II, sonographic evidence of skeletal abnormalities may be evident by 13 weeks' gestation.

Non-invasive prenatal diagnosis of osteogenesis imperfecta

The main mode of non-invasive prenatal diagnosis of osteogenesis imperfecta (OI) is fetal imaging, either by radiography or detailed ultrasonography. Radiography is more of historical interest and ultrasonography is in practice virtually exclusively used for non-invasive second trimester diagnosis of OI. Both methods have also been reported later in pregnancy when diagnosis allows the most appropriate method of delivery to be planned. For example, a caesarean section can be avoided if the fetus is shown to have a form of OI associated with limited survival. Ultrasonography is useful mainly for prenatal diagnosis of the severe forms of OI, especially the perinatally lethal forms (Sillence type II) and to a lesser extent for the severe progressively deforming forms (Sillence types III and III/IV). For the milder varieties of OI (Sillence types I and IV), many cases will be missed by scans. Invasive methods of prenatal diagnosis of OI (principally chorion villous sampling) are used for families with the milder dominant forms of OI and in severe forms of OI in which the actual biochemical or molecular defect in type I collagen is known. Many cases of type II OI and a few of type III have now been reported which were detected by scans before 20 weeks gestation, the earliest being at 15 weeks, for type IIA OI. These include cases not only at genetic risk but also sporadic cases in which scans were done either routinely or for obstetric indications. The ultrasonic abnormalities which are found include reduced echogenicity, multiple fractures, and deformity of the long bones, ribs and skull.(ABSTRACT TRUNCATED AT 250 WORDS)

Anencephaly in a fetus with osteogenesis imperfecta: early diagnosis by transvaginal sonography

Early prenatal diagnosis of osteogenesis imperfecta at 14 weeks' gestation by transvaginal sonography is reported. An anencephalic fetus was found at autopsy, although on sonographic examination complete brain tissue had been observed. A possible explanation for these findings and theories on the pathogenesis of anencephaly are discussed.

Prenatal counselling and diagnosis in progressively deforming osteogenesis imperfecta: a case of autosomal dominant transmission

A 21-year-old woman with progressively deforming or type III osteogenesis imperfecta (OI) presented for prenatal counselling and diagnosis at 10 weeks' gestation. Family history was non-contributory. At 14.8 weeks' gestation, ultrasonographic examination revealed fetal skeletal hypomineralization, easily compressible fetal cranium, and thickened long bones, indicating that the fetus was also affected. Confirmation of the prenatal diagnosis of OI type III was made following a Caesarean section birth of a male infant with multiple skeletal deformities and blue sclerae implying, in this case, autosomal dominant inheritance.

Prenatal diagnosis of severe osteogenesis imperfecta

The ultrasound findings in a series of 15 prenatally diagnosed cases of severe osteogenesis imperfecta types IIA, IIB, IIC, and III are described, eleven being detected on routine scans of women with no relevant history. As most cases of osteogenesis imperfecta type IIA are dominant sporadic mutations, the importance of prenatal diagnosis during routine scanning at a local level is emphasized. In addition to characteristic broad, shortened and fractured long bones, striking features of the chest and head are highlighted which may be encountered during a routine scan, prompting further assessment.

Studies of type I collagen in osteogenesis imperfecta

We used the results of skin fibroblast type I collagen analysis to improve the accuracy of diagnosis and genetic counseling for six patients with osteogenesis imperfecta. The fibroblasts of two patients with osteogenesis imperfecta type I synthesized a reduced quantity of qualitatively normal type I procollagen. Another patient with osteogenesis imperfecta type I had two populations of type I collagen molecules, one apparently normal and the other with a substitution of cysteine for glycine in the triple helical domain. Three sporadic cases with osteogenesis imperfecta types II, III, and IV were studied; in each proband a normal and an abnormal overmodified population of type I collagen molecules were demonstrated, and parental collagens were normal in the two available patients. These results indicated that the probands were heterozygous for new dominant mutations and assisted our genetic counseling, especially in osteogenesis imperfecta types II and III, which were formerly believed to be inherited in an autosomal recessive fashion. The results could not exclude parental germ line mosaicism for a new dominant mutation, which has resulted in recurrence in siblings of some patients with osteogenesis imperfecta, so prenatal diagnosis was therefore offered for future pregnancies. Analysis of chorionic villus cell collagen may facilitate antenatal diagnosis in selected cases, and the study of a larger number of patients may allow correlation of the biochemical defects with the natural history and prognosis.

Prenatal ultrasonographic diagnosis of radial-ray reduction malformations

Radial-ray reduction malformations (RRRMs) may occur isolated or in association with other anomalies. The data of seven fetuses born with RRRMs were collected. Six fetuses had associated lethal abnormalities of the central nervous system, urogenital system, and/or heart, detected by ultrasound. In five cases, it was possible to establish the precise diagnosis, enabling an informed prognosis and subsequent genetic counselling. The diagnoses were: Edwards syndrome (n = 3), VACTERL association (n = 1), and Poland-Moebius-like complex (n = 1). In two cases, a complete diagnosis was not possible because of inadequate evaluation of these fetuses before and/or after birth. A proposal is given for the diagnostic approach for infants with RRRMs detected in the antenatal period by means of ultrasonography.

Radiological "metamorphosis" in a patient with severe congenital osteogenesis imperfecta

Congenital osteogenesis imperfecta (OI) was diagnosed by ultrasound in a 31-week-old fetus, and the diagnosis confirmed after delivery by caesarean section at week 36. The baby survived the neonatal period, but failed to thrive, had recurrent respiratory infections and ultimately died at 8 months. Cultured fibroblasts synthesized both normal type I collagen and unstable type I collagen harbouring a structural defect in the alpha 1 (I) cyanogen bromide-derived peptide number 8 (CB8) region of the molecule, indicating a heterozygous dominant mutation. At birth, the radiological picture was that of the "thin bone"-type of congenital OI (OI type IIB/III in the Sillence classification); at the age of 12 weeks ribs and long bones had undergone a marked expansion giving a very different picture, that of the "thick bone"-type congenital OI (OI type IIA). The mechanism responsible for this change in bone structure is not known, but fractures and callus formation are unlikely to be the only factors. Caution is needed in the interpretation of radiographs of newborns with OI for prognostic or genetic purposes.

Ratios between growth parameters for the prenatal ultrasonographic diagnosis of skeletal dysplasias

The clinical applicability and usefulness of nine ratios that express the relation between particular fetal growth parameters were tested in ten fetuses affected by skeletal dysplasia. The results were compared with the ratios calculated from five growth-retarded fetuses without structural anomalies. Femur/foot, femur/head circumference, head circumference/thoracic circumference and abdominal circumference/thoracic circumference ratios are useful additional parameters for the prenatal ultrasonographic diagnosis of skeletal dysplasias. They reduce the problem of an unknown gestational age and help to distinguish between fetal skeletal dysplasia and intra-uterine growth-retardation caused by other factors.

The prenatal development of the normal human skeleton: a combined ultrasonographic and post-mortem radiographic study

Post-mortem radiography of fetuses with skeletal dysplasia is essential for diagnostic classification. Interpretation of the radiographs should be based on the knowledge of morphology and dimensions of the normal skeleton in all stages of development. A retrospective post-mortem radiographic study is presented with measurements of the lengths of the long bones and thoracic and lumbar spine. The study included 69 fetuses and neonates with a normal skeleton, whose gestational age ranged from 13-42 weeks and who died perinatally or lived for less than one week. The measurements of the long bones were plotted on growth curves obtained from a prospective longitudinal ultrasonographic investigation of another group of 63 normal fetuses from 12-40 weeks of gestation. Thoracic and lumbar spine measurements by ultrasonography were not available. The radiographic data of thoracic and lumbar spine were, therefore, compared to radiographic studies from the literature. No disagreement with these studies was found. It can be concluded that measurements of bones from standardized post-mortem radiographs in cases of questionable gestational age or defects of bone development can be compared with ultrasonographic measurements. To illustrate the usefulness of the graphs, 13 fetuses with various types of skeletal dysplasia were evaluated retrospectively.