The present disclosure provides methods for determining the ploidy status of a chromosome in a gestating fetus from genotypic data measured from a mixed sample of DNA comprising DNA from both the mother of the fetus and from the fetus, and optionally from genotypic data from the mother and father. The ploidy state is determined by using a joint distribution model to create a plurality of expected allele distributions for different possible fetal ploidy states given the parental genotypic data, and comparing the expected allelic distributions to the pattern of measured allelic distributions measured in the mixed sample, and choosing the ploidy state whose expected allelic distribution pattern most closely matches the observed allelic distribution pattern. The mixed sample of DNA may be preferentially enriched at a plurality of polymorphic loci in a way that minimizes the allelic bias, for example using massively multiplexed targeted PCR.

Disclosed are compositions and methods for nucleic acid amplification and detection. Specifically, disclosed herein are compositions and methods that allow for amplification of nucleic acids at a wide variety of temperatures. This includes a polymerase which is thermostable at high temperatures, and a method of amplification that can be conducted at relatively low temperatures.

Disclosed are compositions and methods for nucleic acid amplification and detection. Specifically, disclosed herein are compositions and methods that allow for amplification of nucleic acids at a wide variety of temperatures. This includes a polymerase which is thermostable at high temperatures, and a method of amplification that can be conducted at relatively low temperatures.

The present disclosure provides, among other things, systems, methods, and kits include internal amplification controls. Provided internal amplification controls are or include non-target sequences that are amplified during nucleic acid amplification. Provided internal amplification controls are linearly amplified. Provided internal amplification controls are useful for systems, methods and kits for nucleic acid amplification.

The present disclosure provides, among other things, systems, methods, and kits include internal amplification controls. Provided internal amplification controls are or include non-target sequences that are amplified during nucleic acid amplification. Provided internal amplification controls are linearly amplified. Provided internal amplification controls are useful for systems, methods and kits for nucleic acid amplification.

Ultraspecific, programmable nucleic acid sensors capable of detecting and preferentially amplifying target DNA molecules comprising a particular SNP or mutation are provided. In some cases, the ultraspecific programmable nucleic acid sensors are useful for detecting SNP-containing DNA molecules indicative of cancer such as cell-free DNA circulating in the blood or indicative of organ transplant rejection Also provided are methods for construction of such ultraspecific nucleic acid sensors and methods for preferential amplification of target DNA molecules containing a mutation of interest, as well as testing systems for early cancer screening and routine monitoring of circulating cancer DNA using liquid biological samples such as serum, plasma, or saliva.

Ultraspecific, programmable nucleic acid sensors capable of detecting and preferentially amplifying target DNA molecules comprising a particular SNP or mutation are provided. In some cases, the ultraspecific programmable nucleic acid sensors are useful for detecting SNP-containing DNA molecules indicative of cancer such as cell-free DNA circulating in the blood or indicative of organ transplant rejection Also provided are methods for construction of such ultraspecific nucleic acid sensors and methods for preferential amplification of target DNA molecules containing a mutation of interest, as well as testing systems for early cancer screening and routine monitoring of circulating cancer DNA using liquid biological samples such as serum, plasma, or saliva.

The present disclosure provides methods for determining the ploidy status of a chromosome in a gestating fetus from genotypic data measured from a mixed sample of DNA comprising DNA from both the mother of the fetus and from the fetus, and optionally from genotypic data from the mother and father. The ploidy state is determined by using a joint distribution model to create a plurality of expected allele distributions for different possible fetal ploidy states given the parental genotypic data, and comparing the expected allelic distributions to the pattern of measured allelic distributions measured in the mixed sample, and choosing the ploidy state whose expected allelic distribution pattern most closely matches the observed allelic distribution pattern. The mixed sample of DNA may be preferentially enriched at a plurality of polymorphic loci in a way that minimizes the allelic bias, for example using massively multiplexed targeted PCR.

The present disclosure provides methods for determining the ploidy status of a chromosome in a gestating fetus from genotypic data measured from a mixed sample of DNA comprising DNA from both the mother of the fetus and from the fetus, and optionally from genotypic data from the mother and father. The ploidy state is determined by using a joint distribution model to create a plurality of expected allele distributions for different possible fetal ploidy states given the parental genotypic data, and comparing the expected allelic distributions to the pattern of measured allelic distributions measured in the mixed sample, and choosing the ploidy state whose expected allelic distribution pattern most closely matches the observed allelic distribution pattern. The mixed sample of DNA may be preferentially enriched at a plurality of polymorphic loci in a way that minimizes the allelic bias, for example using massively multiplexed targeted PCR.

Disclosed are a method for marking 5-formyl cytosine and the use thereof in single base resolution sequencing. The method for marking the 5-formyl cytosine comprises the following steps of: (1) preparing a DNA or RNA sample; and (2) mixing the DNA or RNA sample with a buffer solution and a compound R.sub.1—CH.sub.2—CN to obtain a marking reaction system; and reacting the compound R.sub.1—CH.sub.2—CN therein with the 5-formyl cytosine in DNA and RNA molecules, and thereby achieving the marking of the 5-formyl cytosine; the reaction process is as in (I) below: ##STR00001##
wherein, R.sub.1 is an electron withdrawing group next to the CH.sub.2 group, preferably —CN, (II) or (III), and more preferably —CN; R is a DNA or RNA molecule connected to the 5-formyl cytosine; and the pH value of the marking reaction system is 7.5-9. On this basis, also provided in the present invention is a sequencing analysis method for the 5-formyl cytosine. The method can be implemented at a single cell level, and can achieve the sequencing of single-base resolution levels.