Patients with cobalamin G or J defect missed by the current newborn screening program: diagnosis and novel mutations

Microfluidic on-chip valve and pump for applications in immunoassays

On-chip valves can simplify a microfluidic chip and make it easy to operate. However, most on-chip valves already reported still need complicated manufacture and sophisticated supporting devices. In this work, we present a straightforward on-chip valve, which can be serially connected, to form an on-chip pump. The liquid can horizontally flow one way by the regular deformations of flexure strips in the two valves at both sides of the chamber under pressure changes in microchannels generated by repeated vertical movements of linear actuators. The volume of this system including the chip and the supporting device is 0.65 cubic decimeters, which is much smaller than that of reported systems with a volume of at least 12 cubic decimeters, and the weight of this system is only 0.56 kg, making it possible for point-of-care testing. We carry out an immunoassay of folic acid on chip, and the results show satisfactory reproducibility with acceptable coefficients of variation. We determine 163 clinical human serum samples for folic acid. Furthermore, we detect transferrin, cobalamin and folic acid simultaneously on one chip with both sandwich and competitive binding immunoassay methods. We anticipate that this on-chip valve and pump can be applied in immunoassays and other biosensing applications.

Current attitudes and preconceptions on newborn genetic screening in the Chinese reproductive-aged population

Purpose

Newborn screening (NBS) applications are limited as they can only cover a few genetic diseases and may have false positive or false negative rates. A new detection program called newborn genetic screening (NBGS) has been designed to address the potential defects of NBS. This study aimed to investigate the perceptions, acceptance, and expectations of childbearing people related to NBGS to provide the basis for the targeted improvement in the NBGS program carried out in Hospitals.

Methods

A questionnaire with 20 items was designed on www.wjx.cn. Individuals who came to the Nanjing maternity and child health care Hospital for consultation from June 2021 to August 2021 participated in the survey. The data of the study was arranged properly and analyzed after the investigation.

Results

A total of 1141 valid questionnaires were collected in the survey, in which the average age of the participants was 31 (± 4) years, and a 1:4 ratio of males to females. Additionally, 65.12% of the participants possessed a bachelor's degree or above qualification. Overall, 50.57% of participants had an annual household income of 100,000–250,000 RMB, while about 86.68% of the participants supported the development of NBGS. The participation cost to pay for NBGS depended on the family incomes; about 59.42% of them were willing to pay a participation fee of 1000–2000 RMB.

Conclusion

Our research provisionally demonstrated that the residents generally supported the use of NBGS, especially those with higher educational degrees, but the understanding of the genetic diseases and NBGS among the low-educated population still needs to be strengthened.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02474-8.

Methionine synthase deficiency: Variable clinical presentation and benefit of early diagnosis and treatment

Methionine synthase deficiency (cblG complementation group) is a rare inborn error of metabolism affecting the homocysteine re-methylation pathway. It leads to a biochemical phenotype of hyperhomocysteinemia and hypomethioninemia. The clinical presentation of cblG is variable, ranging from seizures, encephalopathy, macrocytic anemia, hypotonia, and feeding difficulties in the neonatal period to onset of psychiatric symptoms or acute neurologic changes in adolescence or adulthood. Given the variable and nonspecific symptoms seen in cblG, the diagnosis of affected patients is often delayed. Medical management of cblG includes the use of hydroxocobalamin, betaine, folinic acid, and in some cases methionine supplementation. Treatment has been shown to lead to improvement in the biochemical profile of affected patients, with lowering of total homocysteine levels and increasing methionine levels. However, the published literature contains differing conclusions on whether treatment is effective in changing the natural history of the disease. Herein, we present five patients with cblG who have shown substantial clinical benefit from treatment with objective improvement in their neurologic outcomes. We demonstrate more favorable outcomes in our patients who were treated early in life, especially those who were treated before neurologic symptoms manifested. Given improved outcomes from treatment of presymptomatic patients, cblG warrants inclusion in newborn screening.

Cobalamin J disease detected on newborn screening: Novel variant and normal neurodevelopmental course

Cobalamin J disease (CblJ) is an ultra-rare autosomal recessive disorder of intracellular cobalamin metabolism associated with combined methylmalonic acidemia and homocystinuria. It is caused by pathogenic variants in ABCD4, which encodes an ATP-binding cassette (ABC) transporter that affects the lysosomal release of cobalamin (Cbl) into the cytoplasm. Only six cases of CblJ have been reported in the literature. Described clinical features include feeding difficulties, failure to thrive, hypotonia, seizures, developmental delay, and hematological abnormalities. Information on clinical outcomes is extremely limited, and no cases of presymptomatic diagnosis have been reported. We describe a now 17-month-old male with CblJ detected by newborn screening and confirmed by biochemical, molecular, and complementation studies. With early detection and initiation of treatment, this patient has remained asymptomatic with normal growth parameters and neurodevelopmental function. To the best of our knowledge, this report represents the first asymptomatic and neurotypical patient with CblJ.