The disease was first described by Patau in 1960 and is therefore also known as Patau syndrome (pediatric Patau’s syndrome). The prevalence is 1/(4000-10000) in newborns, significantly more in females than in males, and the incidence increases with maternal age. The main features of the disease are severe mental retardation, peculiar facial features, hand, foot and genital malformations, and can be accompanied by severe lethal malformations, 90% of which die within one year of age. Karyotype analysis: simple 13-trisomy 75%, translocation 20%, chimerism 5%. The chimeric type usually has mild symptoms, and the translocation type usually has a predominance of 13 and 14 Roche translocations. The patient has a t(13q14q) translocation chromosome with karyotype 46, -14, +t(13q14q), which results in an extra long arm of 13. When one of the two parents is a balanced translocation carrier, the risk of producing an affected child is no more than 5% or 1% because the majority of abnormal fetuses are aborted and die . If one of the parents is a 13q13q translocation carrier, the miscarriage rate is 100% because only trisomy or monosomy congeners can be produced. Clinical manifestations: The malformations and clinical manifestations of affected children are much more severe than in trisomy 21. Craniofacial malformations include microcephaly, forehead tilt, sagittal suture and wide autoglossus, holoprosencephaly or forebrain malformation, localized scalp defects in the parieto-occipital region, forehead capillary hemangioma, microphthalmia, iris fissure, retinal hypoplasia, wide eye spacing, low malformed ears, central labial and/or stunned cleft, small collar, round face in infancy, and short neck with dermatome. Malformations of the brain and internal organs are very common, such as anosmia, congenital heart disease (mostly ventricular septal defect, patent ductus arteriosus, or atrial septal defect), thin or absent ribs, renal malformations, and deafness due to defective inner ear spiracles. Mental retardation is seen in all patients and is severe, with seizure-like epilepsy and hypotonia in longer surviving children. A single umbilical artery, persistent fetal hemoglobin, and pelvic dysplasia are present. Multiple deformities such as ulnar (or platysmal) polydactyly (or toe) hyperconvex and narrow nails, overlapping flexed fingers, rocker foot, congenital clubfoot, etc. Heel bone protrusion, through the palm, palm distal axis three rays; big toe fat arch or “5” type or tibial skip, linear fish interval, except for the index finger for flexion skip, especially the thumb, abnormal tone. Males often have scrotal malformation and cryptorchidism, while females have ovarian dysplasia, clitoral hypertrophy, double vagina, bicornuate uterus, and spina bifida. Less than 5% survive to 3 years of age, with an average life expectancy of 130 days. The surviving children have poor life skills and are not easily fed due to facial deformities. Asphyxia, seizure-like epilepsy and severe mental retardation are common, making care extremely difficult. The advanced age of the mother may be one of the reasons, with a mean age of 31.6 years for the mother and 34.6 years for the father of the child. In addition, it is well documented that 79% of cases are gestated in the cold season (September-February). Examination 1. cytogenetic examination: karyotype analysis of chromosomes; 2. molecular cytogenetic examination: broken in situ hybridization (i.e., FISH technique) with lymphocytes or amniotic fluid cells in peripheral blood using a fluorescein-labeled probe with the corresponding fragment sequence of chromosome 13, presenting a fluorescent signal of three chromosomes 13 in the cells of patients with this disease; 3. persistence of blood methemoglobin and neutrophils with Drumstick bodies are increased. Diagnosis Typical cases are not difficult to make clinical judgments based on specific facial features, intellectual backwardness, and multiple malformations, but karyotype analysis should be performed to confirm the diagnosis and determine the type. In chimeric cases, newborns or those with atypical symptoms, karyotype analysis is more necessary to confirm the diagnosis. Prenatal diagnosis is currently the best way to reduce the number of children born with trisomy 13. The main methods are as follows: 1. Prenatal ultrasonography: Most of the children have bilateral cleft lip and palate, polydactyly and congenital heart disease on ultrasonography. The main advantage of this method is that it is non-invasive, and the disadvantage is that it does not confirm the diagnosis. 2. Serological screening: The risk value of fetal development of trisomy 13 can be derived from a comprehensive risk assessment by detecting AFP, Free-βhCG and uE3 in maternal serum during early or mid-pregnancy combined with maternal age, weight and gestational week. The main advantage of this method is that it is non-invasive and inexpensive; the disadvantage is that the detection rate is low, and even if the screening result is negative or low risk, it only indicates that the fetus has a low chance of developing trisomy 13, but does not completely exclude the possibility of developing trisomy 13. This method is suitable for singleton pregnancies in which the expected age is less than 35 years; 3. FISH detection: detection of fetal chromosome 13 number abnormalities by chorionic villus puncture or amniocentesis. The advantages of this method are: the detection time is short, generally 3-5 days to produce results; the disadvantage is: the test is invasive, is a screening method, can not confirm the diagnosis; 4, non-invasive prenatal screening: the detection of fetal free DNA in maternal plasma through gene sequencing, to derive the risk value of fetus suffering from trisomy 13. The main advantages of this method are: it is non-invasive, the best detection week is 12-22+6 weeks, and the detection rate is high, up to 99%; the disadvantage is: it can only be used for screening, not for diagnosis. If the screening result is positive, amniocentesis and umbilical cord blood sampling are required to confirm the diagnosis. This method is suitable for pregnant women of advanced age and high risk of serological screening who do not want to undergo invasive prenatal diagnosis; 5. Chromosomal karyotype analysis: the material is taken by chorionic villus puncture, amniotic fluid puncture or umbilical cord blood puncture, cell culture is performed, and then the fetal chromosomal karyotype is analyzed. The advantage of this method is that it can confirm the diagnosis of trisomy 13, which is currently the “gold standard” for prenatal diagnosis of fetal chromosomal disorders, and can detect all chromosomal number abnormalities and chromosomal structure abnormalities with fragments larger than 10MB; the disadvantage is that because it is an invasive test, there is a possibility of bleeding, amniotic fluid leakage and miscarriage. This method is suitable for pregnant women whose due date is greater than or equal to 35 years old, pregnant women who have given birth to a child with chromosomal abnormalities, pregnant women with chromosomal abnormalities in one of the spouses, pregnant women at high risk for serological screening or non-invasive prenatal screening, and other cases where amniotic fluid specimens need to be taken for examination.