Ligase IV syndrome can present with microcephaly and radial ray anomalies similar to Fanconi anaemia plus fatal kidney malformations.

Ligase IV (LIG4) syndrome is a rare disorder of DNA damage repair caused by biallelic, pathogenic variants in LIG4. This is a phenotypically heterogeneous condition with clinical presentation varying from lymphoreticular malignancies in developmentally normal individuals to significant microcephaly, primordial dwarfism, radiation hypersensitivity, severe combined immunodeficiency and early mortality. Renal defects have only rarely been described as part of the ligase IV disease spectrum. We identified a consanguineous family where three siblings presenting with antenatal growth retardation, microcephaly, severe renal anomalies and skeletal abnormalities, including radial ray defects. Autozygosity mapping and exome sequencing identified a novel homozygous frameshift variant in LIG4, c.597_600delTCAG, p.(Gln200LysfsTer33), which segregated in the family. LIG4 is encoded by a single exon and so this frameshift variant is predicted to result in a protein truncated by 678 amino acids. This is the shortest predicted LIG4 protein product reported and correlates with the most severe clinical phenotype described to date. We note the clinical overlap with Fanconi anemia and suggest that LIG4 syndrome is considered in the differential diagnosis of this severe developmental disorder.

Upper limb phocomelia: A prenatal case of thrombocytopenia-absent radius (TAR) syndrome illustrating the importance of chromosomal microarray in limb reduction defects.

OBJECTIVE: To describe the ultrasonographic, pathologic and molecular findings in a fetus with TAR syndrome, and to illustrate the contribution of chromosomal microarray analysis (CMA) to the etiological investigation of fetal upper limb reduction defects. CASE REPORT: A 35-year-old woman was referred for Genetic Counseling after pregnancy termination for severe upper limb bilateral phocomelia detected in the second trimester. Fetal autopsy showed severe shortening of the arms and forearms. The fetal skeletal survey confirmed the absence of the radii, ulnae and humeri. CMA revealed an interstitial deletion in 1q21 including the RBM8A gene. Subsequent Sanger sequencing of this gene identified a hypomorphic mutant allele, c.-21G > A, confirming the diagnosis of TAR syndrome. CONCLUSION: The differential diagnosis of upper limb defects is broad. Identification of their cause is essential for adequate genetic counseling including prognosis and recurrence risk estimation. CMA should be considered in fetuses with upper limb reduction defects, especially when the thumbs are present.

Quantitative anatomy of the primary ossification center of the radial shaft in human fetuses.

PURPOSE: The medical literature still lacks studies on the size of the radial shaft primary ossification center, thus preventing us from potentially relevant data in diagnosing skeletal dysplasias, i.e., TAR syndrome, VATER syndrome, Holt-Oram syndrome, Fanconi anemia and Edwards syndrome, frequently characterized by disrupted or retarded fetal growth. MATERIALS AND METHODS: The size of the radial shaft primary ossification center in 47 (25 males and 22 females) spontaneously aborted human fetuses aged 17-30 weeks was studied by means of CT, digital image analysis and statistics. RESULTS: With neither sex nor laterality differences, the best-fit growth dynamics for the radial shaft primary ossification center was modeled by the following functions: y = - 10.988 + 1.565 × age ± 0.018 for its length, y = - 2.969 + 0.266 × age ± 0.01 for its proximal transverse diameter, y = - 0.702 + 0.109 × age ± 0.018 for its middle transverse diameter, y = - 2.358 + 0.203 × age ± 0.018 for its distal transverse diameter, y = -189.992 + 11.788 × (age)2 ± 0.018 for its projection surface area, and y = - 798.174 + 51.152 × age ± 0.018 for its volume. CONCLUSIONS: The morphometric characteristics of the radial shaft primary ossification center show neither sex nor bilateral differences. The radial shaft primary ossification center grows proportionately in length, transverse dimensions and volume, and quadratically in its projection surface area. The obtained numerical findings of the radial shaft ossification center are considered age-specific reference of relevance in both the estimation of fetal ages and the diagnostic process of congenital defects.

Prenatal diagnosis of radial ray defects by ultrasound: A report of 6 cases.

OBJECTIVE: All of the medical records of fetuses with the sonographic finding of radial ray defects (RRDs) between 2008 and 2015 were retrieved. The associated sonographic findings, cytogenetic results, and necropsy findings were correlated. CASE REPORT: There were 6 cases of RRD. Three cases were bilateral and the other 3 cases were unilateral. The gestational ages at diagnosis were between 12 and 24 weeks gestation. All women carrying fetuses with RRDs opted to terminate the pregnancy. There were 2 cases of trisomy 18, one case of thrombocytopenia-absent radius syndrome, and 2 cases of isolated RRD. Both cases of trisomy 18 had other sonographic abnormalities. CONCLUSION: RRD should be considered if a short radius and abnormal angulation of the wrist or thumb is noted. The use of 3-D ultrasound facilitates the diagnosis of RRD, even at early gestation, by providing a better surface appearance, panoramic views, and spatial orientation.

Cross-sectional study of fetal long-bone length in an Iranian population at 17-25 weeks of gestation.

OBJECTIVE: To construct improved reference charts for fetal long bones in an Iranian setting and to compare them with previous studies. METHODS: The present prospective cross-sectional study included singleton fetuses assessed by ultrasonography at 17-25 weeks of gestation at the Comprehensive Medical Genetics Center, Shahid Soltani, Shiraz, Iran between May 1, 2012, and February 28, 2014. Exclusion criteria included conditions that could affect fetal growth. Fetal long bones (femur, humerus, tibia, fibula, ulna, and radius) were measured with ultrasonography and biometric charts were produced. Regression models were fitted to estimate bone lengths. The models produced were compared with those from previous studies in other populations. RESULTS: There were 660 singleton fetuses included and 660 femur, 633 humerus, 512 tibia, 498 fibula, 505 ulna, and 498 radius biometric measurements were recorded. The models generated to predict the length of the tibia, fibula, ulna, and radius from the length of the femur and humerus demonstrated a high goodness of fit when the predicted lengths were plotted against the actual lengths. Comparisons of mean lengths with previous studies suggested that long-bone length was affected by maternal ethnicity. CONCLUSION: The equations generated could be used to predict long-bone length in an Iranian population and ethnicity should be considered when using fetal long-bone length as a prenatal diagnostic tool.

Leptin administration affects growth and skeletal development in a rat intrauterine growth restriction model: preliminary study.

OBJECTIVE: Skeletal abnormalities are one of the hallmarks of growth delay during gestation. The aim of this study was to determine changes induced by leptin in skeletal growth and development in a rat model of intrauterine growth retardation (IUGR) and to elucidate the possible underlying mechanisms. METHODS: Intrauterine growth retardation was induced prepartum and the effects of leptin to mothers prenatally or to offspring postnatally were studied. Radii were harvested and tested mechanically and structurally. Tibias were evaluated for growth-plate morphometry. RESULTS: On day 40 postpartum, total bone length and mineral density and tibial growth-plate width and numbers of cells within its zones of offspring treated with leptin were significantly greater than in the control group. CONCLUSION: Postnatal leptin administration in an IUGR model improves the structural properties and elongation rate of bone. These findings could pave the way to preventing some phenotypic presentations of IUGR.

Are distributions of secondary osteon variants useful for interpreting load history in mammalian bones?

BACKGROUND/AIMS: In cortical bone, basic multicellular units (BMUs) produce secondary osteons that mediate adaptations, including variations in their population densities and cross-sectional areas. Additional important BMU-related adaptations might include atypical secondary osteon morphologies (zoned, connected, drifting, elongated, multiple canal). These variants often reflect osteonal branching that enhances toughness by increasing interfacial (cement line) complexity. If these characteristics correlate with strain mode/magnitude-related parameters of habitual loading, then BMUs might produce adaptive differences in unexpected ways. METHODS: We carried out examinations in bones loaded in habitual torsion (horse metacarpals) or bending: sheep, deer, elk, and horse calcanei, and horse radii. Atypical osteons were quantified in backscattered images from anterior, posterior, medial, and lateral cortices. Correlations were determined between atypical osteon densities, densities of all secondary osteons, and associations with habitual strain mode/magnitude or transcortical location. RESULTS: Osteon variants were not consistently associated with 'tension', 'compression', or neutral axis ('shear') regions, even when considering densities or all secondary osteons, or only osteon variants associated with relatively increased interfacial complexity. Similarly, marrow- and strain-magnitude-related associations were not consistent. CONCLUSION: These data do not support the hypothesis that spatial variations in these osteon variants are useful for inferring a habitual bending or torsional load strain history.

Teratogenic mechanisms of longitudinal deficiency and cleft hand.

In order to better understand the teratogenic mechanisms of congenital defects of the digits, we analyzed clinical cases and induced similar types of congenital hand anomalies in rat fetuses by oral administration of busulfan. In clinical cases, radial and ulnar deficiencies had common characteristic features. We induced radial and ulnar deficiencies in rat fetuses with the same drug. Radial and ulnar deficiencies induced in rats have similar clinical manifestations and these anomalies might be caused by the same teratogenic mechanism. Then, the formation of the digital rays was examined histologically. The results of histological examination suggested that these deficiencies were not caused by localized damage of the limb bud. They also suggested that the cause of missing digits in longitudinal deficiency is closely related to a deficit of mesenchymal cells in the limb bud. Cleft hand is considered to be one of the types of longitudinal deficiency. However, several investigators have suggested that the abnormal induction of finger rays in the process of formation of fingers induced central polydactyly, osseous syndactyly and also cleft hand. X-rays of the clinical cases and skeletal changes of the anomalies induced in rats appear to demonstrate that cleft hand formation proceeds from osseous syndactyly and central polydactyly. The results of our experimental study show that the critical periods of central polydactyly, osseous syndactyly and cleft hand are the same. They also suggest that central polydactyly, syndactyly and cleft hand might be induced when the same teratogenic factor acts on embryos at the same developmental stage in the human being. Because they have a similar causation, cleft hand, syndactyly and central polydactyly should be classified into the same entity, that is, abnormal induction of digital rays. Based on these clinical and experimental studies, we modified the Swanson classification. In our modified classification, typical cleft hand, syndactyly and polydactyly are included in the same category of abnormal induction of digital rays as the fourth new category.

Multiple roles of Hoxa11 and Hoxd11 in the formation of the mammalian forelimb zeugopod.

Mutations in the 5' or posterior murine Hox genes (paralogous groups 9-13) markedly affect the formation of the stylopod, zeugopod and autopod of both forelimbs and hindlimbs. Targeted disruption of Hoxa11 and Hoxd11 or Hoxa10, Hoxc10 and Hoxd10 result in gross mispatterning of the radius and ulna or the femur, respectively. Similarly, in mice with disruptions of both Hoxa13 and Hoxd13, development of the forelimb and hindlimb autopod is severely curtailed. Although these examples clearly illustrate the major roles played by the posterior Hox genes, little is known regarding the stage or stages at which Hox transcription factors intersect with the limb development program to ensure proper patterning of the principle elements of the limb. Moreover, the cellular and/or molecular bases for the developmental defects observed in these mutant mice have not been described. In this study, we show that malformation of the forelimb zeugopod in Hoxa11/Hoxd11 double mutants is a consequence of interruption at multiple steps during the formation of the radius and ulna. In particular, reductions in the levels of Fgf8 and Fgf10 expression may be related to the observed delay in forelimb bud outgrowth that, in turn, leads to the formation of smaller mesenchymal condensations. However, the most significant defect appears to be the failure to form normal growth plates at the proximal and distal ends of the zeugopod bones. As a consequence, growth and maturation of these bones is highly disorganized, resulting in the creation of amorphous bony elements, rather than a normal radius and ulna.