Femur and humerus length in trisomy 21 fetuses at 11-14 weeks of gestation

Green Tea Catechins Modulate Skeletal Development with Effects Dependent on Dose, Time, and Structure in a down Syndrome Mouse Model

Altered skeletal development in Down syndrome (DS) results in a brachycephalic skull, flattened face, shorter mandibular ramus, shorter limbs, and reduced bone mineral density (BMD). Our previous study showed that low doses of green tea extract enriched in epigallocatechin-3-gallate (GTE-EGCG), administered continuously from embryonic day 9 to postnatal day 29, reduced facial dysmorphologies in the Ts65Dn (TS) mouse model of DS, but high doses could exacerbate them. Here, we extended the analyses to other skeletal structures and systematically evaluated the effects of high and low doses of GTE-EGCG treatment over postnatal development in wild-type (WT) and TS mice using in vivo µCT and geometric morphometrics. TS mice developed shorter and wider faces, skulls, and mandibles, together with shorter and narrower humerus and scapula, and reduced BMD dynamically over time. Besides facial morphology, GTE-EGCG did not rescue any other skeletal phenotype in TS treated mice. In WT mice, GTE-EGCG significantly altered the shape of the skull and mandible, reduced the length and width of the long bones, and lowered the BMD. The disparate effects of GTE-EGCG depended on the dose, developmental timepoint, and anatomical structure analyzed, emphasizing the complex nature of DS and the need to further investigate the simultaneous effects of GTE-EGCG supplementation.

Interaction of sexual dimorphism and gene dosage imbalance in skeletal deficits associated with Down syndrome

All individuals with Down syndrome (DS), which results from trisomy of human chromosome 21 (Ts21), present with skeletal abnormalities typified by craniofacial features, short stature and low bone mineral density (BMD). Differences in skeletal deficits between males and females with DS suggest a sexual dimorphism in how trisomy affects bone. Dp1Tyb mice contain three copies of all of the genes on mouse chromosome 16 that are homologous to human chromosome 21, males and females are fertile, and therefore are an excellent model to test the hypothesis that gene dosage influences the sexual dimorphism of bone abnormalities in DS. Dp1Tyb as compared to control littermate mice at time points associated with bone accrual (6 weeks) and skeletal maturity (16 weeks) showed deficits in BMD and trabecular architecture that occur largely through interactions between sex and genotype and resulted in lower percent bone volume in all female and Dp1Tyb male mice. Cortical bone in Dp1Tyb as compared to control mice exhibited different changes over time influenced by sex × genotype interactions including reduced cortical area in both male and female Dp1Tyb mice. Mechanical testing analyses suggested deficits in whole bone properties such as bone mass and geometry, but improved material properties in female and Dp1Tyb mice. Sexual dimorphisms and the influence of trisomic gene dosage differentially altered cellular properties of male and female Dp1Tyb bone. These data establish sex, gene dosage, skeletal site and age as important factors in skeletal development of DS model mice, paving the way for identification of the causal dosage-sensitive genes. Skeletal differences in developing male and female Dp1Tyb DS model mice replicated differences in less-studied adolescents with DS and established a foundation to understand the etiology of trisomic bone deficits.

Skeletal dynamics of Down syndrome: A developing perspective

Individuals with Down syndrome (DS) display distinctive skeletal morphology compared to the general population, but disparate descriptions, methodologies, analyses, and populations sampled have led to diverging conclusions about this unique skeletal phenotype. As individuals with DS are living longer, they may be at a higher risk of aging disorders such as osteoporosis and increased fracture risk. Sexual dimorphism has been suggested between males and females with DS in which males, not females, experience an earlier decline in bone mineral density (BMD). Unfortunately, studies focusing on skeletal health related to Trisomy 21 (Ts21) are few in number and often too underpowered to answer questions about skeletal development, resultant osteoporosis, and sexual dimorphism, especially in stages of bone accrual. Further confounding the field are the varied methods of bone imaging, analysis, and data interpretation. This review takes a critical look at the current knowledge of DS skeletal phenotypes, both from human and mouse studies, and presents knowledge gaps that need to be addressed, differences in research methodologies and analyses that affect the interpretation of results, and proposes guidelines for overcoming obstacles to understand skeletal traits associated with DS. By examining our current knowledge of bone in individuals with Ts21, a trajectory for future studies may be established to provide meaningful solutions for understanding the development of and improving skeletal structures in individuals with and without DS.

Natural History and Clinical Significance of Multiple Cysts in a Single Choroid Plexus

Different types and locations of choroid plexus cysts (CPCs) have been described, including oversized and bilateral. It appears that the type, size, and number of CPCs are correlated with various degrees of aneuploidy risk. This report deals with the natural history and significance of CPCs filling only one choroid plexus. Multiple CPCs filling the entire choroid plexus were detected in 9 of 4211 consecutive second-trimester sonographic examinations. Karyotyping via amniocentesis or neonatal blood analysis was performed in all cases. CPCs in a single choroid plexus were associated with transient ventriculomegaly in five of nine fetuses. Resolution of CPCs took place between 25 and 33 weeks of pregnancy, with most resolving after the 30th week. Karyotyping revealed normal results in all cases. Favorable prognosis of newly described multiple CPCs in a single choroid plexus should be mentioned during patient counseling.

Growth charts for Brazilian children with Down syndrome: Birth to 20 years of age

BACKGROUND

The growth of youth with Down syndrome (DS) differs from that of youth without DS, and growth charts specific to DS have been developed. However, little is known about the growth of Brazilian youth with DS. The objective of this study was to construct growth charts for Brazilian youth with DS and compare the growth data with the Child Growth Standards of the World Health Organization (WHO) and charts for children with DS from other studies.

METHODS

Mixed longitudinal and cross-sectional data were collected at University of Campinas, 48 specialized centers for people with intellectual disabilities, and two foundations for people with DS between 2012 and 2015. A total of 10,516 growth measurements from birth to 20 years of age were available from 938 youth with DS (53.7% boys) born between 1980 and 2013. The Lambda Mu Sigma method was applied to construct the curves using generalized additive models for location, scale, and shape.

RESULTS

Length/height-for-age, weight-for-age, and head circumference-for-age percentile curves were generated for Brazilian boys and girls from birth to 20 years of age. Differences in growth of Brazilian youth ranged from -0.8 to -3.2 z-scores compared to WHO standards, and -1.9 to +1.3 compared to children with DS in other studies.

CONCLUSIONS

These specific growth charts may guide clinicians and families in monitoring the growth of Brazilian children and adolescents with DS.

Abnormal mineralization of the Ts65Dn Down syndrome mouse appendicular skeleton begins during embryonic development in a Dyrk1a-independent manner

The relationship between gene dosage imbalance and phenotypes associated with Trisomy 21, including the etiology of abnormal bone phenotypes linked to Down syndrome (DS), is not well understood. The Ts65Dn mouse model for DS exhibits appendicular skeletal defects during adolescence and adulthood but the developmental and genetic origin of these phenotypes remains unclear. It is hypothesized that the postnatal Ts65Dn skeletal phenotype originates during embryonic development and results from an increased Dyrk1a gene copy number, a gene hypothesized to play a critical role in many DS phenotypes. Ts65Dn embryos exhibit a lower percent bone volume in the E17.5 femur when compared to euploid embryos. Concomitant with gene copy number, qPCR analysis revealed a  ~1.5 fold increase in Dyrk1a transcript levels in the Ts65Dn E17.5 embryonic femur as compared to euploid. Returning Dyrk1a copy number to euploid levels in Ts65Dn, Dyrk1a(+/-) embryos did not correct the trisomic skeletal phenotype but did return Dyrk1a gene transcript levels to normal. The size and protein expression patterns of the cartilage template during embryonic bone development appear to be unaffected at E14.5 and E17.5 in trisomic embryos. Taken together, these data suggest that the dosage imbalance of genes other than Dyrk1a is involved in the development of the prenatal bone phenotype in Ts65Dn embryos.

Narrowed beam width in newer ultrasound machines shortens measurements in the lateral direction: fetal measurement charts may be obsolete

OBJECTIVES

Fetal ultrasound measurements are made in axial, lateral and oblique directions. Lateral resolution is influenced by the beam width of the ultrasound system. To improve lateral resolution and image quality, the beam width has been made narrower; consequently, measurements in the lateral direction are affected and apparently made shorter, approaching the true length. The aims of this study were to explore our database to reveal time-dependent shortening of ultrasound measurements made in the lateral direction, and to assess the extent of beam-width changes by comparing beam-width measurements made on old and new ultrasound machines.

METHODS

A total of 41,941 femur length measurements, collected during the time-period 1987-2005, were analyzed, with time as a covariate. Using three ultrasound machines from the 1990s and three newer machines from 2007, we performed 25 series of blinded beam-width measurements on a tissue-mimicking phantom, measuring at depths of 3-8 cm with a 5-MHz transducer.

RESULTS

Regression analysis showed time to be a significant covariate. At the same gestational age, femur length measurement was 1.15 (95% CI, 1.08-1.23) mm shorter in the time-period 1999-2005 than in the time-period 1987-1992. Overall, the beam width was 1.08 (95% CI, 0.50-1.65) mm narrower with the new machines than with the old machines.

CONCLUSIONS

Technical improvements in modern ultrasound machines that have reduced the beam width affect fetal measurements in the lateral direction. This has clinical implications and new measurement charts are needed.

Disruption of bone development and homeostasis by trisomy in Ts65Dn Down syndrome mice

Down syndrome (DS) is a genetic disorder resulting from trisomy 21 that causes cognitive impairment, low muscle tone and craniofacial alterations. Morphometric studies of the craniofacial and appendicular skeleton in individuals with DS suggest that bone development and homeostasis are affected by trisomy. The Ts65Dn mouse model has three copies of approximately half the genes found on human chromosome 21 and exhibits craniofacial skeletal and size differences similar to those observed in humans with DS. We hypothesized that Ts65Dn and euploid mice have distinct differences in bone development and homeostasis influencing both the craniofacial and appendicular skeletal phenotypes. Quantitative assessment of structural and mechanical properties of the femur in Ts65Dn and control mice at 6 and 16 weeks of age revealed significant deficiencies in trabecular and cortical bone architecture, bone mineral density, bone formation, and bone strength in trisomic bone. Furthermore, bone mineral density and dynamic dentin formation rate of the skull and incisor, respectively, were also reduced in Ts65Dn mice, demonstrating that trisomy significantly affects both the craniofacial and appendicular skeleton.

Evaluation of the usefulness of the fetal femur length with respect to gestational age to detect Down syndrome in Korean subjects

OBJECTIVE

We investigated the usefulness of shortening of the fetal femur length (FL) to predict Down syndrome at different gestational ages in Korean subjects.

METHODS

This study involved 110 Korean Down syndrome fetuses and 602 randomly selected euploid controls. The expected FL for any biparietal diameter (BPD) was calculated based on the control group data. Subjects were divided into four groups according to gestational age periods: 14-18 weeks; 19-23 weeks; 24-28 weeks and 29-36 weeks. The value of measured/expected FL ratio to predict Down syndrome was analyzed for each group.

RESULTS

The values of FL for any BPD in Down syndrome patients were significantly different from those in the control group (p < 0.001). A low ratio of measured/expected FL increased the risk of fetal Down syndrome (p < 0.001) with a mean measured/expected FL in Down syndrome of 0.907 (SD 0.075). At a fixed false positive rate of 5%, the sensitivities of FL were lower than 32.8% (95% CI 0.705-0.915) in three second trimester groups, and 71.1% (95% CI 0.924-0.997) in the third trimester group.

CONCLUSION

Short FL is a poor marker of Down syndrome in the second trimester in Korean subject. It may be used as a screening marker only in the third trimester.

[Screening of chromosomal abnormalities--the focus is on the first trimester]

<zakljucak> U savremenoj perinatologiji skriningu hromozomopatija posvecuje se velika paznja i postojece metode se stalno unapredjuju. Bez obzira koji test koristili, treba biti samokritican - ultrazvucni pregled u prvom trimestru je veoma vazan ne samo zbog markera hromozomopatija, nego i iskljucivanja postojanja velikih defekata fetusa, te je potrebno napraviti detaljan pregled. Merenje nuhalne translucencije je jedan od najvaznijih koraka ovog procesa, i preporucuje se da svi operateri koji pristupaju proceni rizika od hromozomopatija prodju adekvatnu obuku i sertifikaciju Fondacije za fetalnu medicinu, radi postizanja adekvatnog nivoa pregleda i reproducibilnosti rezultata. Laboratorije koje se bave biohemijskim skriningom i u prvom i u drugom trimestru moraju biti sertifikovane za to, te imati stalnu spoljnu kontrolu kvaliteta rezultata, jer je u protivnom vise kako lazno pozitivnih, tako i lazno negativnih nalaza, sto smanjuje stopu detekcije. Veoma je vazno da se pacijentima uvek napomene i to da se radi o procesu skrininga, ma koliko efikasan on bio, a ne definitivne dijagnoze i da se dijagnoza moze postaviti samo na osnovu invazivne intervencije i odredjivanja kariotipa ploda. .

Choroid plexus cyst, intracardiac echogenic focus, hyperechogenic bowel and hydronephrosis in screening for trisomy 21 at 11 + 0 to 13 + 6 weeks

OBJECTIVES

To investigate the potential value of choroid plexus cyst, intracardiac echogenic focus, hydronephrosis and hyperechogenic bowel as markers of trisomy 21 at 11 + 0 to 13 + 6 weeks.

METHODS

We examined three-dimensional volumes from 228 fetuses with trisomy 21 and 797 chromosomally normal fetuses at 11 + 0 to 13 + 6 weeks of gestation. We looked for choroid plexus cysts with a minimum diameter of 1.5 mm, intracardiac echogenic focus, hydronephrosis with a minimum anteroposterior diameter of the pelvis of 1.5 mm and hyperechogenic bowel.

RESULTS

The prevalence of intracardiac echogenic focus, hydronephrosis and hyperechogenic bowel was significantly higher in trisomy 21 than in normal fetuses (9.6% vs. 1.5%, 17.1% vs. 5.3% and 11.4% vs. 2.4%, respectively). There was no significant difference between the two groups in the prevalence of choroid plexus cysts (7.5% vs. 5.0%). There were no significant differences in crown-rump length or nuchal translucency thickness in either chromosomally normal or trisomy 21 fetuses between those with and those without any one of the markers.

CONCLUSIONS

At 11 + 0 to 13 + 6 weeks the prevalence of intracardiac echogenic focus, hydronephrosis and hyperechogenic bowel is higher in trisomy 21 than in chromosomally normal fetuses. As there is no significant association between the presence of these markers and nuchal translucency thickness, they could be included in the assessment of risk to improve accuracy of screening.

First trimester ultrasonography in screening and detection of fetal anomalies

An obstetrical ultrasound examination provides invaluable information regarding the fetus. Until the mid-1980s, ultrasound in the first trimester was limited to localization of the pregnancy, establishing viability, and accurate dating. With the advent of high-resolution ultrasound and transvaginal scanning, a significant amount of information about the fetus can be gained and provided to the patient at a very early stage in gestation. This article provides an overview of the role of first trimester (11-13 + 6 weeks' gestation) ultrasound in screening and diagnosis of fetal anomalies. The first trimester is an ideal time for screening for aneuploidy, primarily due to the advantages that nuchal translucency (NT) measurement provides. NT measurement is also useful in establishing the risk of congenital cardiac disorders and a number of genetic and non-genetic syndromes. Significant NT thickening is associated with an increase in perinatal morbidity and mortality. Potential mechanisms resulting in increased NT are discussed. A number of new ultrasound markers for fetal aneuploidy have been investigated over the past several years, some of which appear to improve the screening efficacy of early ultrasonography. The role of these is reviewed. A number of fetal anomalies can now be consistently diagnosed in the first trimester. Their appearance at this early gestational age is discussed as well. It is clear that, data obtained by first trimester ultrasound are useful in counseling expectant parents and in planning the appropriate follow-up.

First-trimester fetal limb biometry in Chinese population

OBJECTIVES

To establish reference ranges for fetal limb biometry obtained by transabdominal ultrasound examination at 12-14 weeks of gestation in Chinese women.

METHODS

A total of 1489 normal singleton fetuses between 12(+0) and 14(+6) weeks of gestation were examined transabdominally by two experienced observers. The gestation was ascertained by measurement of fetal crown-rump length (CRL) or biparietal diameter (BPD) and head circumference (HC). The lengths of the humerus and femur were prospectively worked out.

RESULTS

Gestation-specific reference ranges for limb measurements were calculated. The femur length (FL) (mean +/- SD) was 9.15 +/- 1.44 mm at 12-12(+6) weeks, 11.45 +/- 1.35 mm at 13-13(+6) weeks, and 13.64 +/- 1.60 mm at 14-14(+6) weeks; the corresponding humerus length (HL) (mean +/- SD) was 9.63 +/- 1.44 mm, 12.01 +/- 1.41 mm, 14.29 +/- 1.48 mm, respectively.

CONCLUSIONS

There was a general increase in fetal limb biometry with gestation. Fetal limb length can be an early marker of early growth restriction as well as fetal skeletal dysplasia among women in the local population.

First-trimester maternal serum level of pregnancy-associated plasma protein-A is an independent predictor of fetal maxillary bone length

OBJECTIVE

To derive a nomogram of fetal maxillary bone length (MAX) for a Chinese population and to study whether first-trimester maternal serum levels of pregnancy-associated plasma protein-A (PAPP-A) is an independent predictor of fetal MAX.

METHODS

This was a prospective observational study over 10 months examining Chinese women with a singleton pregnancy who attended the first-trimester screening program for Down syndrome. The subjects had the fetal crown-rump length (CRL), nuchal translucency, MAX, maternal serum PAPP-A and free beta-human chorionic gonadotropin (fbeta-hCG) levels measured. A nomogram of MAX was derived using normal pregnancies with reliable dates. The correlations between MAX, CRL, PAPP-A and fbeta-hCG levels were studied, after correction for gestational dependency using Z-score transformation for the ultrasound markers (Z-MAX and Z-CRL), and logarithmic transformation of multiple of gestation-specific medians for the biochemical markers (log10PAPP-A multiples of the median (MoM) and log10fbeta-hCG MoM), using the Pearson test and multiple regression analysis.

RESULTS

During the study period, 607 Chinese women met the inclusion criteria. The mean gestational age at the first-trimester screening was 12 + 4 weeks (SD, 4 days). Curve estimation analysis showed that a linear relationship fit best between MAX and CRL (MAX (mm) = -0.01 + 0.101 * CRL (mm); r = 0.826; P < 0.0001), and between MAX and gestational age (MAX (mm) = -8.465 + 0.170 * gestational age (day); r = 0.754; SD = 0.71; P < 0.0001). There were significant positive correlations between Z-MAX and Z-CRL (r = 0.627; P = < 0.0001), Z-MAX and log10PAPP-A MoM (r = 0.239; P = < 0.0001). Multiple regression analysis showed that both Z-CRL (P = < 0.0001) and log10 PAPP-A MoM (P = 0.048) were independent predictors for Z-MAX.

CONCLUSION

Both CRL and maternal levels of PAPP-A are independent predictors of the fetal MAX measured during the first trimester. The positive correlation between PAPP-A levels and fetal MAX is consistent with the known biological function of PAPP-A on bone growth. This association must be adjusted for when both PAPP-A and MAX are combined for screening of Down syndrome.

Short hard palate in prenatal trisomy 21

OBJECTIVE

The aim of the present study was for the first time to examine on postmortal material the total midpalatal length of the hard palate and the length of its two components (the maxillary and palatine parts) in trisomy 21 fetuses, and to compare the results to normal standards.

DESIGN

Material from 31 human fetuses with genetically verified trisomy 21 was studied. The fetuses were derived from legally induced or spontaneous abortions. Palates were, after sectioning, radiographed in lateral projection (Grenz Ray radiographic apparatus). Cephalometric measurements were performed with a digital caliper. Statistically, the length measurements for the two groups were compared, adjusting for crown rump length (CRL) through linear regression. At two specific ages (150 and 170 mm CRL), the length of the palatal components in trisomy 21 was compared to normal standards.

RESULTS

For CRL 150 mm and CRL 170 mm it appears that all three palatal lengths, total length, maxillary length, and palatinal length are significantly shorter in fetuses with trisomy 21.

CONCLUSION

The main conclusion of our study is that the total palatal length in prenatal trisomy 21 is shorter than normal and that this is due both to a shortness of the maxillary and the palatine components of the hard palate.