1 Introduction
Birth
defects (also known as congenital anomalies) are the major causes of
neonatal deaths, worldwide. According to the report on prevention and
treatment of birth defects-Ministry of Public Health of China in 2012,
the incidence of birth defects in China is about 5.6%, with
approximately 900000 new cases of birth defects every
year1. To reduce the occurrence of birth defects, the
World Health Organization (WHO) develops prevention strategies into
three levels based on the causes and epidemiology of birth defects:
preconception care to increase the
likelihood of a healthy infant delivery, pregnancy care to reduce the
birth rate of defective infant, newborn infant and child care to
decrease disability, mortality, and serious consequences of birth
defects2. 3 periods-screening (Preconception
screening, Peri-conception screening, Neonatal screening) prevent
different diseases of birth defects. Newborn screening (NBS) is the last
step against birth defects, which aims to identify seriously harmful
diseases in the neonatal period. It is helpful for early diagnosis,
early intervention (as reducing exposure to risk factors), and early
management of the diseases, thus preventing mortality and morbidity of
children3,4.
NBS begins in the 1960s when Professor
Guthrie firstly applied the method
of bacterial inhibition to screen phenylketonuria (PKU) in the dried
blood spots5.
Since then, NBS has gradually
expanded under the screening guiding principles with the progression of
clearly-investigated diseases, the feasibility of screening methods, and
the increment of public conscientious 6,7. In 2006,
the American college of medical genetics (ACMG) expert group published
and continually updated the Recommended Uniform Screening Panel (RUSP)
for NBS consensus with 35 primary and 26 secondary
conditions8. While in China, NBS started in 1981,
mainly focused on the screening of PKU, congenital hypothyroidism (CH)
firstly, followed by deafness, glucose-6-phosphate dehydrogenase (G6PD)
deficiency, congenital adrenal hyperplasia (CAH), and so
on9. With the expansion of screening diseases, NBS
methods have developed from the initial low throughput biochemical
approach to high throughput molecular biology technology. Tandem mass
spectrometry (MS) is the main conventional NBS method and has been
widely used in clinical practice for the last 20 years, with the feature
of rapid, sensitive, and high throughput10. Although
MS accelerated the development of NBS, it is now well established from a
variety of studies that MS has a high false-positive/negative
ratio4,11,12. Besides, conventional NBS covered a
limited range of diseases. New methods are urgently needed for
complementing the shortcomings of MS and other conventional NBS.
Recently, high-throughput
sequencing technology has been widely used in tumor-targeted genes
test13, pathogen detection14, as
well as 3 periods-screening of birth defects15.
Laboratories have successfully carried out studies on sequencing
technology as an NBS method16-18 and indicated
sequencing could be used as a second-tier confirmation for conventional
NBS of some diseases19,20. Besides, the ability of
sequencing for the gene diagnosis of Neonatal Intensive Care Units
(NICU) patients has also been uncovered by multiple
studies21,22. However, there are several concerns
about the use of sequencing in NBS. 1) Interpretation of the gene
variant site. Sequencing may identify lots of variants with uncertain
significance (VUS), while the relationship between many genes and
diseases is not clear. 2) Report of the results. There is no
gene-disease association list about conditions that are treatable and
preventable so far. 3) Personalized sequencing panel. Sequencing
protocols and panels specifically designed for NBS are lacking. 4)
Clinical trials of the whole population. Most of the previous studies
focused on the use of sequencing in ill infants, or for the screening
for a specific disease, studies about multiple monogenic-disease
screening in healthy newborns are not fully understood. These big
challenges for the application of sequencing in NBS are presented and
aroused great interest in this field.
Based on the above-mentioned
challenges, researchers devoted to establishing proper criteria of
gene-disease association list and reporting strategies for newborn gene
sequencing since the year 2012 23,24. However, this
gene-disease association list and
reporting strategy cannot be fully applied, as the high incidence of
monogenic diseases in the Chinese population is quite different from
that of other countries, due to different races and geographical areas.
Here, we systemically evaluated the NGS methods used in NBS, designed
the severe, actionable, and early-onset inherited gene-disease list for
the Chinese population, established the featured NGS panel (NeoExome),
performed a multi-center study to verify its feasibility with 3423
neonates, and compared the NeoExome panel with other NGS panels of NBS.
(Supplementary Fig. 1)