[Genetic features of a case with mosaic ring chromosome 4 and a review of the literature].

OBJECTIVE: To explore the genetic basis, clinical phenotype and pathogenesis for a child with mosaicism ring chromosome 4. METHODS: Clinical data of the child was collected. Peripheral blood chromosomal karyotype G banding analysis, chromosomal microarray analysis (CMA), fluorescence in situ hybridization (FISH) were carried out for the child, in addition with a review of the literature. RESULTS: The child was born full-term with low birth weight, facial dysmorphism, patent ductus arteriosus and ventricular septal defect. His karyotype was determined as mos46,XY,r(4)(p16.3q35.2)[259]/45,XY,-4[25]/47,XY,r(4)(p16.3q35.2), +r(4)(p16.3q35.2)[8]/46,XY,der(4)del(4)(p16.3)inv(4)(p16.3q31.1)[6]/46,XY,dic?r(4;4)(p16.3q35.2;p16.3q35.2)[4]/48,XY,r(4)(p16.3q35.2),+r(4)(p16.3q35.2)×2[3]/46,XY,r(4)(p1?q2?)[2]; CMA result was arr[GRCH37]4p16.3(68 345-2 981 614)×1; FISH result was 45,XY,-4[12]/45,XY,-4×2,+mar1.ish r1(4)(WHS-,D4Z1+)[1]/ 46,XY,-4,+mar1.ishr1(4)(WHS-,D4Z1+)[73]/46,XY,-4,+mar2.ishr2(4)(WHS-,D4Z1++)[1]/47,XY,-4,+mar1×2.ishr1(4) (WHS-, D4Z1+)×2[4]/46,XY,del(4)(p16.3).ish del(4)(p16.3)(WHS-,D4Z1+)[9]. CONCLUSION: In this case, the ring chromosome 4 as a de novo variant has produced a number of cell lines during embryonic development and given rise to mosaicism. The clinical phenotype of ring chromosome 4 is variable. The instability of the ring chromosome itself, presence of mosaicism, chromosome breakpoint and range of deletion and/or duplication may all affect the ultimate phenotype.

Head-nodding: a driving force for the circulation of cerebrospinal fluid.

The myodural bridge (MDB) is a dense connective tissue bridge connecting the suboccipital muscles to the spinal dura mater, and it has been proven to be a normal common existing structure in humans and mammals. Some scholars believe that the suboccipital muscles can serve as a dynamic cerebrospinal fluid (CSF) pump via the MDB, and they found head rotations promote the CSF flow in human body, which provided evidence for this hypothesis. Head movement is a complex motion, but the effects of other forms of head movement on CSF circulation are less known. The present study explored the effects of head-nodding on CSF circulation. The CSF flow of 60 healthy volunteers was analyzed via cine phase-contrast magnetic resonance imaging at the level of the occipitocervical junction before and after one-minute-head-nodding period. Furthermore, the CSF pressures of 100 volunteers were measured via lumbar puncture before and after 5 times head-nodding during their anesthetizing for surgical preparation. As a result, it was found that the maximum and average CSF flow rates at the level of the upper border of atlas during ventricular diastole were significantly decreased from 1.965 ± 0.531 to 1.839 ± 0.460 ml/s and from 0.702 ± 0.253 to 0.606 ± 0.228 ml/s respectively. In the meantime, the changes in the ratio of cranial and caudal orientation of the net flow volume were found differed significantly after the one-minute-head-nodding period (p = 0.017). And on the other hand, the CSF pressures at the L3-L4 level were markedly increased 116.03 ± 26.13 to 124.64 ± 26.18 mmH2O. In conclusion, the head-nodding has obvious effects on CSF circulation and head movement is one of the important drivers of cerebrospinal fluid circulation. We propose that the suboccipital muscles, participating in various head movements, might pull the dura sac via the myodural bridge, and thus, head movement provides power for the CSF circulation.