Génétique humaine et Embryologie

Heterotopic ossification (HO) is caused by trauma, neurogenic insults, and genetic disorders. Recent detailed analyses have revealed a cellular origin for ectopic bone formation as novel mesenchymal progenitors. The differentiation of these into osteogenic lineages is induced by a pathological microenvironment in soft tissues outside the skeletal tissue, which includes inflammation. Multiple therapeutic strategies for preventing ectopic bone formation have recently emerged, including inhibition of bone morphogenetic protein signaling and retinoid signaling.

Molecular and paleontological dating indicates human appearance 6 million years ago. Early hominin fossils show that they were bipeds. Three salient characteristics distinguish humans from other primates: bipedality, practical nakedness, and the family reproductive unit. Once a hairless mutation was initially introduced, the three characteristics became separately inexplicable. All primates except humans can carry their babies without using their hands. A hairless mother would be forced to stand and walk upright to hold a baby. Her activities would be markedly limited. The male partner would have to collect food and carry it to her to keep their baby from starving; irresponsible and selfish males could not have left their offspring. The mother would have sexually accepted her partner at any time as a reward for food. Sexual relations irrespective of estrus cycles might have strengthened the pair bond. Consequently, hairless and upright pairs would have established strong families. Early hominins had the opposable hallux and remained as arboreal denizens. Climate changes probably forced them to terrestrial life, but the ground was full of danger and trees were indispensable for refuge and nesting. Consequently, archaic hominins had mosaic characteristics of the upper body adapted for arboreal life and the lower body for terrestrial life, for which a larger brain became advantageous. Alternative strategies became possible: development of a large pelvis with a big birth canal through which a baby with a big head could pass, or delivery of an immature baby, with rearing after birth. The former was physically incompatible with an upright posture, and structurally unfavorable for swift movement. The latter was unavailable to primates, the babies of which had to cling to the mother; upright hominins were able to hold the immature baby with hands and raise it after birth.

Caudal regression syndrome (CRS) is a rare congenital disorder in which lumbosacral anomalies are combined with anorectal and urogenital malformations. However, the molecular mechanisms of human CRS are not yet known. Trauma, nutritional problems, toxic agents, and genetics are suggested in the etiology of CRS. To the best of our knowledge, linkage studies of families affected exclusively by CRS or total sacral agenesis have not been conducted. In spite of the small number of familial cases reported, some specific genes have been shown to cause defined phenotypes. Environmental factors also may act as an enhancer in the etiology for CRS. There are several mutant mice that are considered as models for CRS, showing characteristic vertebral, anorectal, and urogenital abnormalities. Understanding the mechanisms for CRS development gives us valuable information to understand better what mutations may cause or contribute to CRS in humans. This review highlights the current evidence that pinpoints the link to the etiology of CRS.

Adipogenesis is the process by which Mesenchymal Stem cells commit to become adipocyte precursor cells, which will later differentiate into mature adipocytes following exposure to differentiation factors. The transcriptional programs involved in the differentiation process have been carefully studied. Recently, small non-coding RNAs, microRNAs, have been found to play critical roles throughout the adipogenic process. MicroRNAs have been identified that are involved in promoting or inhibiting adipogenesis by targeting anti- or pro-adipogenic factors and cell cycle regulatory proteins. Here, we will discuss the latest discoveries regarding microRNA regulation of adipocyte differentiation.

Background: This audit aimed to evaluate the cases Kawasaki disease (KD) seen in the pediatric department of a community hospital over a 10-year-period. In particular, length of time to diagnosis and variations in treatment were reviewed. Possible effects of these factors on patient outcome in the acute and chronic phase of KD were analyzed. Methods: Data were obtained from the hospital information and coding departments. The following parameters were studied: demographic characteristics, presenting signs and symptoms, duration and peak of fever, hemoglobin and platelet count, coagulation times, C-reactive protein, urine dipstick analysis, length of hospital admission and cardiovascular abnormalities. The data were compared using standard computer software. Results: Eleven patients were identified. Seven of them were male, and the mean age was 35 months. Mean length of hospital stay was 5 days. Mean time from admission to diagnosis was 4 days. All but one patient were given one course of immunoglobulin upon diagnosis. Two developed coronary artery aneurysms and were still receiving aspirin therapy at the time of the audit. Eight of the 11 patients were treated with antibiotics during their time in hospital, all prescribed to treat suspected infections. Once KD had been confirmed antibiotics were stopped. Conclusion: A retrospective case note audit was performed which found that delay in diagnosis may be associated with cardiac complications. The data analyzed highlight the importance of early diagnosis and adequate treatment of KD. It is likely that new genetic tests will help clinicians achieve these goals in the near future.