Prenatal diagnosis of a case with complete and uniform tetrasomy 12p by the utility of noninvasive prenatal testing

PURPOSE

To report a rare type of Pallister-Killian syndrome (PKS) diagnosed prenatally by the utility of non-invasive prenatal testing (NIPT).

METHODS

NIPT was performed in the first trimester. Conventional karyotyping and chromosomal microarray analysis (CMA) were performed on the amniotic samples in the second trimester. Copy number variation sequencing (CNV-seq) was used for the validation of fetal skin and the placental tissue after pregnancy termination.

RESULTS

NIPT results showed increased signal from chromosome 12p. Subsequent prenatal diagnostic testing by karyotype revealed 47, XY, +i (12p), and CMA displayed four copies of 12p: 12p13.33-12p11.1(173786_34835641) × 4. The CNV-seq results of the fetal skin and the fetal side of placenta showed four copies of 12p13.33-p11 and an estimated chimeric duplication of 34.08 Mb (chimerism ratio: 10%) in 12 p13.33-p11, respectively. However, no abnormality was detected by CNV-seq at the maternal side of placenta.

CONCLUSIONS

Our findings suggest that a positive signal from chromosome 12p on NIPT should raise suspicion for PKS. With the wide application of NIPT, the true positive of incidental finding is expected to increase.

Functional Covariance Connectivity of Gray and White Matter in Olfactory-Related Brain Regions in Parkinson’s Disease

Before the onset of motor symptoms, Parkinson’s disease (PD) involves dysfunction of the anterior olfactory nucleus and olfactory bulb, causing olfactory disturbance, commonly resulting in hyposmia in the early stages of PD. Accumulating evidence has shown that blood oxygen level dependent (BOLD) signals in white matter are altered by olfactory disorders and related stimuli, and the signal changes in brain white matter pathways show a certain degree of specificity, which can reflect changes of early olfactory dysfunction in Parkinson’s disease. In this study, we apply the functional covariance connectivity (FCC) method to decode FCC of gray and white matter in olfactory-related brain regions in Parkinson’s disease. Our results show that the dorsolateral prefrontal, anterior entorhinal cortex and fronto-orbital cortices in the gray matter have abnormal connectivity with the posterior corona radiata and superior corona radiata in white matter in patients with Parkinson’s hyposmia. The functional covariance connection strength (FCS) of the right dorsolateral prefrontal cortex and white matter, and the covariance connection strength of the left superior corona radiata and gray matter function have potential diagnostic value. These results demonstrate that alterations in FCC of gray and white matter in olfactory-related brain regions can reflect the change of olfactory function in the early stages of Parkinson’s disease, indicating that it could be a potential neuroimaging marker for early diagnosis.

Generation and Characterization of Monoclonal Antibodies Against Tth DNA Polymerase and its Application to Hot-Start PCR

BACKGROUND

As a heat-resistant polymerase, Thermus thermophilus (Tth) DNA polymerase can be widely used in Polymerase Chain Reaction (PCR). However, its non-specific amplification phenomenon is serious, which greatly limits development.

OBJECTIVE

In this study, we prepared Tth monoclonal antibodies against Tth DNA polymerase and researched their application in hot-start PCR.

METHODS

Tth was recombinantly expressed and purified, and used as an antigen to immunize BALB/ c mice to obtain monoclonal antibodies. The qualified monoclonal antibody and Tth were incubated for a period of time at a certain temperature to obtain the hot-start Tth. We tested the polymerase activity and exonuclease activity blocking the performance of hot-start Tth. Finally, the hot-start Tth was applied to one-step RT-PCR.

RESULTS

Tth with a purity of >95% was obtained, and ten monoclonal antibodies were obtained by immunization. After incubation, three monoclonal antibodies were identified that could inhibit the polymerase activity of Tth at low temperature. Furthermore, these three antibodies successfully eliminated non-specific amplification in practical applications.

CONCLUSION

Three monoclonal antibodies were successfully validated. Among them, monoclonal antibody 9 had the best overall effect. They possess the function of inhibiting at low temperature and releasing at high temperature, which can be used as Tth polymerase inhibitors in the field of molecular diagnostics.