Prevalence of common autosomal recessive mutation carriers in women in the Southern Vietnam following the application of expanded carrier screening.

The common autosomal recessive (AR) mutation carrier is still unknown in Vietnam. This study aims to identify the most common AR gene mutation carriers in women of reproductive age to build a Vietnamese-specific carrier screening panel for AR and X-linked disorders in the preconception and prenatal healthcare program. A cross-sectional study was conducted at University Medical Center-Branch 2 in Ho Chi Minh City from December 1st, 2020, to June 30th, 2023. 338 women have consented to take a 5 mL blood test to identify 540 recessive genes. The carrier screening panel was designed based on the American College of Medical Genetics and Genomics (ACMG)-recommended genes and suggestions from 104 clinical experts in Vietnam. Obstetricians and genetic experts counseled all positive testing results to discuss the possibility of recessive diseases in their offspring. The most common recessive disorders were defined at a prevalence of 1 in 60 or greater, and those were added to a Vietnamese-specific carrier screening panel. 338 non-pregnant and pregnant women underwent the expanded carrier screening (ECS). The carrier frequency was 63.6%, in which 215 women carried at least one AR gene mutation. GJB2 hearing impairment was identified as the most common chronic condition (1 in 5). The second most common AR disorder was beta-thalassemia (1 in 16), followed by cystic fibrosis (1 in 23), G6PD deficiency (1 in 28), Wilson's disease (1 in 31), Usher's syndrome (1 in 31), and glycogen storage disease (1 in 56). Seven common recessive genes were added in ethnic-based carrier screening. Women in the South of Vietnam have been carried for many recessive conditions at high frequency, such as hearing impairment, genetic anemia, and cystic fibrosis. It is necessary to implement a preconception and prenatal screening program by using seven widely popular AR genes in a Vietnamese-specific carrier screening panel to reduce the burden related to AR and X-linked disorders.

Prenatal diagnosis of non-typical Chiari malformation type I associated with de novo Nuclear Factor I A gene mutation: a case report.

BACKGROUND: Chiari malformation is one of the most common Central nervous system (CNS) abnormalities that can be detected in routine fetal scanning. Chiari malformation type I (CMI) is a congenital defect characterized by a displacement of the cerebellar tonsils through the foramen magnum. The etiology of CMI has not been well established and suggested having multifactorial contributions, especially genetic deletion. Clinical characteristics of this anomaly may express in different symptoms from neurological dysfunction and/or skeletal abnormalities in the later age, but it is rarely reported in pregnancy. CASE PRESENTATION: We present a case in which the Chiari malformation type I was diagnosed with comorbidities of facial anomalies (flatting forehead and micrognathia) and muscular-skeletal dysmorphologies (clenched hands and clubfeet) at the 24+6 weeks of gestation in a 29-year-old Vietnamese pregnant woman. The couple refused an amniocentesis, and the pregnancy was followed up every 4 weeks until a spontaneous delivery occurred at 38 weeks. The newborn had a severe asphyxia and seizures at birth required to have an emergency resuscitation at delivery. He is currently being treated in the intensive neonatal care unit. He carries the novel heterozygous NFIA gene mutation confirmed after birth. No further postnatal malformation detected. CONCLUSION: CMI may only represent with facial abnormalities and muscle-skeletal malformations at the early stage of pregnancy, which may also alert an adverse outcome. A novel heterozygous NFIA gene mutation identified after birth helps to confirm prenatal diagnosis of CMI and to provide an appropriate consultation.

Fabrication and Evaluation of N-Channel GaN Metal-Oxide-Semiconductor Field-Effect Transistors Based on Regrown and Implantation Methods.

We have demonstrated the enhancement-mode n-channel gallium nitride (GaN) metal-oxide field-effect transistors (MOSFETs) on homoepitaxial GaN substrates using the selective area regrowth and ion implantation techniques. Both types of MOSFETs perform normally off operations. The GaN-MOSFETs fabricated using the regrowth method perform superior characteristics over the other relative devices fabricated using the ion implantation technique. The electron mobility of 100 cm2/V·s, subthreshold of 500 mV/dec, and transconductance of 14 µs/mm are measured in GaN-MOSFETs based on the implantation technique. Meanwhile, the GaN-MOSFETs fabricated using the regrowth method perform the electron mobility, transconductance, and subthreshold of 120 cm2/V s, 18 µs/mm, and 300 mV/dec, respectively. Additionally, the MOSFETs with the regrown p-GaN gate body show the Ion/Ioff ratio of approximately 4 × 107, which is, to our knowledge, among the best results of GaN-MOSFETs to date. This research contributes a valuable information for the design and fabrication of power switching devices based on GaN.