Of those fetuses that do survive to gestation and subsequent birth, common abnormalities may include:

- Nervous system

- Intellectual disability and motor disorder

- Microcephaly

- Holoprosencephaly (failure of the forebrain to divide properly).

- Structural eye defects, including microphthalmia, Peters' anomaly, cataract, iris or fundus (coloboma), retinal dysplasia or retinal detachment, sensory nystagmus, cortical visual loss, and optic nerve hypoplasia

- Meningomyelocele (a spinal defect)

- Musculoskeletal and cutaneous

- Polydactyly (extra digits)

- Cyclopia

- Proboscis

- Congenital trigger digits

- Low-set ears

- Prominent heel

- Deformed feet known as rocker-bottom feet

- Omphalocele (abdominal defect)

- Abnormal palm pattern

- Overlapping of fingers over thumb

- Cutis aplasia (missing portion of the skin/hair)

- Cleft palate

- Urogenital

- Abnormal genitalia

- Kidney defects

- Other

- Heart defects (ventricular septal defect) (Patent Ductus Arteriosus)

- Dextrocardia

- Single umbilical artery

Complete trisomy 8 causes severe effects on the developing fetus and can be a cause of miscarriage.

Complete trisomy 8 is usually an early lethal condition, whereas trisomy 8 mosaicism is less severe and individuals with a low proportion of affected cells may exhibit a comparatively mild range of physical abnormalities and developmental delay. Individuals with trisomy 8 mosaicism are more likely to survive into childhood and adulthood, and exhibit a characteristic and recognizable pattern of developmental abnormalities. Common findings include retarded psychomotor development, moderate to severe mental retardation, variable growth patterns which can result in either abnormally short or tall stature, an expressionless face, and many musculoskeletal, visceral, and eye abnormalities, as well as other anomalies. A deep plantar furrow is considered to be pathognomonic of this condition, especially when seen in combination with other associated features. The type and severity of symptoms are dependent upon the location and proportion of trisomy 8 cells compared to normal cells.

Infants with Emanuel syndrome have weak muscle tone (hypotonia) and fail to gain weight and grow at the expected rate (failure to thrive). Their development is significantly delayed, and most affected individuals have severe to profound intellectual disability. Other features of Emanuel syndrome include an unusually small head (microcephaly), distinctive facial features, and a small lower jaw (micrognathia). Ear abnormalities are common, including small holes in the skin just in front of the ears (preauricular pits or sinuses). About half of all affected infants are born with an opening in the roof of the mouth (cleft palate) or a high arched palate. Males with Emanuel syndrome often have genital abnormalities. Additional signs of this condition can include heart defects and absent or unusually small (hypoplastic) kidneys; these problems can be life-threatening in infancy or childhood.

Children born with Edwards syndrome may have some or all of these characteristics: kidney malformations, structural heart defects at birth (i.e., ventricular septal defect, atrial septal defect, patent ductus arteriosus), intestines protruding outside the body (omphalocele), esophageal atresia, intellectual disability, developmental delays, growth deficiency, feeding difficulties, breathing difficulties, and arthrogryposis (a muscle disorder that causes multiple joint contractures at birth).

Some physical malformations associated with Edwards syndrome include small head (microcephaly) accompanied by a prominent back portion of the head (occiput), low-set, malformed ears, abnormally small jaw (micrognathia), cleft lip/cleft palate, upturned nose, narrow eyelid folds (palpebral fissures), widely spaced eyes (ocular hypertelorism), drooping of the upper eyelids (ptosis), a short breast bone, clenched hands, choroid plexus cysts, underdeveloped thumbs and/or nails, absent radius, webbing of the second and third toes, clubfoot or rocker bottom feet, and in males, undescended testicles.

"In utero", the most common characteristic is cardiac anomalies, followed by central nervous system anomalies such as head shape abnormalities. The most common intracranial anomaly is the presence of choroid plexus cysts, which are pockets of fluid on the brain. These are not problematic in themselves, but their presence may be a marker for trisomy 18. Sometimes, excess amniotic fluid or polyhydramnios is exhibited.

Symptoms may include tall stature, vertical skin folds that may cover the inner corners of the eyes (epicanthal folds), poor muscle tone, and a curve in the 5th finger towards the 4th. There may also be a small head (microcephaly). There are seldom any observable physical anomalies in triple X females, other than being taller than average.

Poor coordination may be present. Those affected appear to have higher rates of scoliosis.

Symptoms of tetrasomy X are highly variable, ranging from relatively mild to severe. Symptoms are often similar to those of trisomy X. Physically, tetrasomy X patients tend to have distinctive facial features such as epicanthal folds, flat nasal bridges, upslanting palpebral fissures, midface hypoplasia, small mouths, cleft or high arched palates, delayed or absent teeth, or enamel defects. The majority have also been reported as being longer and taller. Many also show joint and muscle tone abnormalities, including hypotonia and joint looseness in the hips. Skeletal problems may also be present, including abnormal curvatures of the spine. An informal study conducted found that 10% of girls had joint laxity in the hips and 20% had joint limitations in a sample size of 20 tetrasomy and pentasomy patients.

Developmentally, people with tetrasomy X frequently show mild delays in the areas of speech development and articulation, language expression and understanding, and reading skills. Delays in motor development are also present, with walking ages ranging from 16 months to 4.5 years. About 50% of patients undergo puberty normally, whereas the other 50% experiences no puberty, partial puberty without secondary sexual characteristics, or complete puberty with menstrual irregularities and/or early menopause (possibly as early as the teens). Medical literature reports four tetra-X pregnancies, two healthy, one with trisomy 21, one stillborn with omphalocele.

In terms of internal organ systems, tetrasomy X patients may have abnormal vision, hearing, circulatory systems, kidneys, or nervous systems. Disorders of the eye include myopia, nystagmus, coloboma, microphthalmus, or optic nerve hypoplasia. In terms of hearing, patients are more prone to ear infections, sound blockage, or nerve abnormalities. Several cardiac defects have also been reported, including ventricular/atrial septal defects, atresia, hypoplastic right heart syndrome, patent ductus arteriosus, and conotruncal or valvular cardiac defects. Tetrasomy X patients also appear to be more prone to seizure activity, although there is no documented abnormalities in brain function or structure when analyzed using an EEG or MRI.

Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division. There are three forms of nondisjunction: failure of a pair of homologous chromosomes to separate in meiosis I, failure of sister chromatids to separate during meiosis II, and failure of sister chromatids to separate during mitosis. Nondisjunction results in daughter cells with abnormal chromosome numbers (aneuploidy).

Calvin Bridges and Thomas Hunt Morgan are credited with discovering nondisjunction in "Drosophila melanogaster" sex chromosomes in the spring of 1910, while working in the Zoological Laboratory of Columbia University.

Patau syndrome is a syndrome caused by a chromosomal abnormality, in which some or all of the cells of the body contain extra genetic material from chromosome 13. The extra genetic material disrupts normal development, causing multiple and complex organ defects.

This can occur either because each cell contains a full extra copy of chromosome 13 (a disorder known as trisomy 13 or trisomy D), or because each cell contains an extra partial copy of the chromosome (i.e., Robertsonian translocation) or because of mosaic Patau syndrome. Full trisomy 13 is caused by nondisjunction of chromosomes during meiosis (the mosaic form is caused by nondisjunction during mitosis).

Like all nondisjunction conditions (such as Down syndrome and Edwards syndrome), the risk of this syndrome in the offspring increases with maternal age at pregnancy, with about 31 years being the average. Patau syndrome affects somewhere between 1 in 10,000 and 1 in 21,700 live births.

Potocki–Lupski syndrome (PTLS), also known as dup(17)p11.2p11.2 syndrome, trisomy 17p11.2 or duplication 17p11.2 syndrome, is a contiguous gene syndrome involving the microduplication of band 11.2 on the short arm of human chromosome 17 (17p11.2). The duplication was first described as a case study in 1996. In 2000, the first study of the disease was released, and in 2007, enough patients had been gathered to complete a comprehensive study and give it a detailed clinical description. PTLS is named for two researchers involved in the latter phases, Drs. Lorraine Potocki and James R. Lupski of Baylor College of Medicine.

PTLS was the first predicted of a homologous recombination (microdeletion or microduplication) where both reciprocal recombinations result in a contiguous gene syndrome. Its reciprocal disease is Smith–Magenis syndrome (SMS), in which the chromosome portion duplicated in PTLS is deleted altogether.

Potocki–Lupski syndrome is considered a rare disease, predicted to appear in at least 1 in 20,000 humans.

Symptoms of the syndrome include intellectual disability, autism, and other disorders unrelated to the listed symptoms.

Because the vast majority of triple X females are never diagnosed, it may be very difficult to make generalizations about the effects of this syndrome. The samples that were studied were small and may be nonrepresentative. Because of the lyonization, inactivation, and formation of Barr bodies in all female cells, only one X chromosome is active at any time. Thus, triple X syndrome most often has only mild effects or has no effects. The symptoms vary from person to person, with some women being more affected than others.

Symptoms vary, but usually result in dysmorphisms in the skull, nervous system, and developmental delay. Dysmorphisms in the heart, kidneys, and musculoskeletal system may also occur. An infant with complete trisomy 9 surviving 20 days after birth showed clinical features including a small face, wide fontanelle, prominent occiput, micrognathia, low set ears, upslanting palpebral fissures, high-arched palate, short sternum, overlapping fingers, limited hip abduction, rocker bottom feet, heart murmurs and also a webbed neck.

Trisomy 9p is one of the most frequent autosomal anomalies compatible with long survival rate. A study of five cases showed an association with Coffin–Siris syndrome, as well as a wide gap between the first and second toes in all five, while three had brain malformations including dilated ventricles with hypogenesis of the corpus callosum and Dandy-Walker malformation.

Young–Madders syndrome is detectable from the fetal stage of development largely due to the distinctive consequences of holoprosencephaly, a spectrum of defects or malformations of the brain and face. Facial defects which may manifest in the eyes, nose, and upper lip, featuring cyclopia, anosmia, or in the growth of only a single central incisor, and severe overlapping of the bones of the skull. Cardiac and in some cases pulmonary deformities are present. Another signature deformity is bilateral polydactyly, and many patients also suffer from hypoplasia and genital deformities.

Edwards syndrome, also known as trisomy 18, is a genetic disorder caused by the presence of all, or part of a third copy of chromosome 18. Many parts of the body are affected. Babies are often born small and have heart defects. Other features include a small head, small jaw, clenched fists with overlapping fingers, and severe intellectual disability.

Most cases of Edwards syndrome occur due to problems during the formation of the reproductive cells or during early development. The rate of disease increases with the mother's age. Rarely cases may be inherited from a person's parents. Occasionally not all cells have the extra chromosome, known as mosaic trisomy, and symptoms in these cases may be less severe. Ultrasound can increase suspicion for the condition, which can be confirmed by amniocentesis.

Treatment is supportive. After having one child with the condition, the risk of having a second is typically around one percent. It is the second-most frequent condition due to a third chromosome at birth, after Down syndrome.

Edwards syndrome occurs in around one in 5,000 live births. Some studies suggest that more babies that survive to birth are female. Many of those affected die before birth. Survival beyond a year of life is around 5-25%. It is named after John Hilton Edwards, who first described the syndrome in 1960.

Trisomy 8, also known as Warkany syndrome 2, is a human chromosomal disorder caused by having three copies (trisomy) of chromosome 8. It can appear with or without mosaicism.

Derivative 22 syndrome, or der(22), is a rare disorder associated with multiple congenital anomalies, including profound mental retardation, preauricular skin tags or pits, and conotruncal heart defects. It can occur in offspring of carriers of the constitutional chromosomal translocation t(11;22)(q23;q11), owing to a 3:1 meiotic malsegregation event resulting in partial trisomy of chromosomes 11 and 22. An unbalanced translocation between chromosomes 11 & 22 is described as Emanuel syndrome. It was characterized in 1980.

Diploid-triploid mosaicism (DTM) is a chromosome disorder. Individuals with diploid-triploid syndrome have some cells with three copies of each chromosome for a total of 69 chromosomes (called triploid cells) and some cells with the usual 2 copies of each chromosome for a total of 46 chromosomes (called diploid cells).

Having two or more different cell types is called mosaicism. Diploid-triploid mosaicism can be associated with truncal obesity, body/facial asymmetry, weak muscle tone (hypotonia), delays in growth, mild differences in facial features, fusion or webbing between some of the fingers and/or toes (syndactyly) and irregularities in the skin pigmentation.

Intellectual disabilities may be present but are highly variable from person to person ranging from mild to more severe.

The chromosome disorder is usually not present in the blood; a skin biopsy, or analyzing cells in the urine is needed to detect the triploid cells.

A regular human carries 23 pairs of chromosomes in his or her cells. Cells containing two pairs of chromosomes are known as diploid cells. Those with diploid triploid mosaicism have some cells which are triploid, meaning that they have three copies of chromosomes, or a total of 69 chromosomes. Triploidy is distinct from trisomy, in which only one chromosome exists in three pairs. A well-known example of trisomy is trisomy 21 or Down syndrome.

Full trisomy 9 is a lethal chromosomal disorder caused by having three copies (trisomy) of chromosome number 9. It can be a viable condition if trisomy affects only part of the cells of the body (mosaicism) or in cases of partial trisomy (trisomy 9p) in which cells have a normal set of two entire chromosomes 9 plus part of a third copy, usually of the short arm of the chromosome (arm p).

Tetrasomy X (also called XXXX syndrome, quadruple X, or 48,XXXX) is a rare chromosomal disorder caused by the presence of four X chromosomes instead of two X chromosomes.

This condition occurs only in females, as there are no Y chromosomes present.

Tetrasomy X was first described in 1961, and since then approximately 100 cases have been reported worldwide. Approximately 60 affected females have been described in the medical literature.

Young–Madders syndrome, alternatively known as Pseudotrisomy 13 syndrome or holoprosencephaly–polydactyly syndrome, is a genetic disorder resulting from defective and duplicated chromosomes which result in holoprosencephaly, polydactyly, facial malformations and mental retardation, with a significant variance in the severity of symptoms being seen across known cases. Many cases often suffer with several other genetic disorders, and some have presented with hypoplasia, cleft lip, cardiac lesions and other heart defects. In one case in 1991 and another in 2000 the condition was found in siblings who were the product of incest. Many cases are diagnosed prenatally and often in siblings. Cases are almost fatal in the prenatal stage with babies being stillborn.

Though it is now thought that earlier cases were misdiagnosed as other genetic disorders with similar pathology—such as Smith–Lemli–Opitz syndrome—the earliest publicised recognition of the condition as a new, hitherto unclassified, genetic disorder was made by two British doctors in Leicester in 1987. Though they identified the condition, later named for them, they did not identify the genetic anomalies responsible but suspected a link with trisomy 13 due to the similar symptoms. With only one or two occurrences documented towards the end of the decade, a group of eight doctors published a five-patient case-study in 1991 which identified the likely chromosomal factors that caused the condition, similar to but distinct from trisomy 13, and gave it the name 'holoprosencephaly–polydactyly syndrome' based on its two most prolific presenting conditions. Later research showed that the condition could manifest in patients with normal karyotypes, without duplication of the chromosomes, and the most recent genetic research implicates problems with the gene code FBXW11 as a likely cause.

Many organ systems are affected by triploidy, but the central nervous system and skeleton are the most severely affected. Common central nervous system defects seen in triploidy include holoprosencephaly, hydrocephalus (increased amount of cerebrospinal fluid within the brain), ventriculomegaly, Arnold-Chiari malformation, agenesis of the corpus callosum, and neural tube defects. Skeletal manifestations include cleft lip/palate, hypertelorism, club foot, and syndactyly of fingers three and four. Congenital heart defects, hydronephrosis, omphalocele, and meningocele (spina bifida) are also common. Cystic hygromas occur but are uncommon. Triploid fetuses have intrauterine growth restriction beginning early in the pregnancy, as early as 12 weeks, and does not affect the head as severely as the body. Oligohydramnios, low levels of amniotic fluid, is common in triploid pregnancies.

Placental abnormalities are common in triploidy. Most frequently, the placenta is enlarged and may have cysts within. In some cases, the placenta may be unusually small, having ceased to grow.

Clinically, PTLS presents as a milder syndrome than SMS, with distinct characteristics, though PTLS can be mistaken for SMS. Both syndromes are characterized by multiple congenital abnormalities and mental retardation. A key feature which appears in 80% of cases is autism spectrum disorder. Other unique features of Potocki–Lupski syndrome include infantile hypotonia, sleep apnea, structural cardiovascular anomalies, cognitive deficits, abnormal social behaviors, learning disabilities, attention-deficit disorder, obsessive-compulsive behaviours, malocclusions, short stature and failure to thrive.

After noting that autism is commonly associated with PTLS, researchers at the Centro de Estudios Científicos and the Austral University of Chile genetically engineered a PTLS "model mouse" where the syntenic chromosome segment was duplicated, and examined the social behaviours of these mice versus those without the anomaly (the "wild-type"). One human autism-related symptom is abnormal social interaction. The researchers observed that the genetically-engineered mice of both sexes had a slight (statistically insignificant) impairment of their preference of a social target (i.e., a living, breathing mouse) over an inanimate one — the average human will prefer the social target — and preferred to explore newly introduced mice instead of familiar ones, unlike the typical human and mouse preference of a friend over a stranger, demonstrating a change in their liking of social novelty. They also found that male mice, in some scenarios, showed increased anxiety and than the control group. Anatomically, the engineered mice had a decreased brain-to-body mass ratio and an alteration in the expression of several genes in the hippocampus.

A ring chromosome is an aberrant chromosome whose ends have fused together to form a ring. Ring chromosomes were first discovered by Lilian Vaughan Morgan in 1926. A ring chromosome is denoted by the symbol "r" in human genetics and "R" in Drosophila genetics. Ring chromosomes may form in cells following genetic damage by mutagens like radiation, but they may also arise spontaneously during development.

Trisomy 22 is a chromosomal disorder in which there are three copies of chromosome 22 rather than two. It is a frequent cause of spontaneous abortion during the first trimester of pregnancy. Progression to the second trimester and live birth are rare. This disorder is found in individuals with an extra copy or a variation of chromosome 22 in some or all cells of their body. There are many kinds of disorders associated with Trisomy 22:

Emanuel Syndrome is named after the genetic contributions made by researcher Dr. Beverly Emanuel. This condition is assigned to individuals born with an unbalanced 11/22 translocation. That is, a fragment of chromosome 11 is moved, or translocated, to chromosome 22.

22q11 Deletion Syndrome is a rare condition which occurs in approximately 1 in 4000 births. This condition is identified when a band in the q11.2 section of the arm of chromosome 22 is missing or deleted. This condition has several different names: 22q11.2 Deletion Syndrome, Velocardiofacial syndrome, DiGeorge Syndrome, Conotruncal Anomaly Face syndrome, Opitz G/BBB Syndrome, and Cayler Cardiofacial Syndrome. The effects of this disorder are different in each individual but similarities exist such as heart defects, immune system problems, a distinctive facial appearance, learning challenges, cleft palate, hearing loss, kidney problems, hypocalcemia, and sometimes psychiatric issues.

22q11 microduplication syndrome is the opposite of the 22q11 deletion syndrome: in this condition, a band of q.11.2 section of chromosome 22 is duplicated. Individuals carrying this deficiency are relatively “normal” as in they don’t possess any major birth defects or major medical illnesses. This microduplication is more common than the deletion; this might be due to the milder phenotype of the individuals.

Phelan-McDermid Syndrome / 22q13 Deletion Syndrome is a condition caused by the deletion of the tip of the q arm on chromosome 22. Most individuals with this disorder experience cognitive delays; low muscle tone; and sleeping, eating, and behavioural issues.

Chromosome Ring 22 is a rare disorder caused by the break and re-join of both ends of chromosome 22, forming a ring. The effects on the individual with this disorder are dependent on the amount of genetic information lost during the break/re-join. Major characteristics for this disorder are intellectual disability, muscle weakness and lack of coordination.

Cat Eye Syndrome / Schmid Fraccaro Syndrome is a condition caused by a partial trisomy or tetrasomy in chromosome 22. A small extra chromosome is found, made up of the top half of chromosome 22 and a portion of the q arm at the q11.2 break. This chromosome can be found three or four times. This syndrome is referred as “Cat Eye” due to the eye appearance of reported affected individuals who have coloboma of the iris; however, this feature is only seen in about half of the cases.

Mosaic trisomy 22 is a disorder in which an extra chromosome 22 is found only in some cells of the body. The severity of each case is determined by the number of cells with this extra copy. Some characteristics of individuals with this condition are cardiac abnormalities, growth retardation, mental delay, etc.

Complete Trisomy 22 is in contrast with Mosaic trisomy 22; this disorder is characterized by an extra copy of chromosome 22 which is found in each cell of the body of the affected individual. These cases are very rare, and most of the affected individuals die before birth or shortly after.

Trisomy 16 is a chromosomal abnormality in which there are 3 copies of chromosome 16 rather than two. It is the most common trisomy leading to miscarriage and the second most common chromosomal cause of it, closely following X-chromosome monosomy. About 6% of miscarriages have trisomy 16. Those mostly occur between 8 to 15 weeks after the last menstrual period.

It is not possible for a child to be born alive with an extra copy of this chromosome present in all cells (full trisomy 16). It is possible, however, for a child to be born alive with the mosaic form.

Chromosome 15q trisomy is an extremely rare genetic disorder, caused by a chromosomal aberration in which there is an excess copy of the long ("q") arm of human chromosome 15. The disorder is also known as Distal Duplication 15q and Partial Duplication 15q Syndrome.

The disorder is primarily characterized by growth abnormalities, which range from growth retardation to accelerated growth, intellectual disability, and distinctive malformations of the head and face. Additional abnormalities may involve malformation of the skeleton, spine and neck; fingers and/or toes; genitals (particularly in males); and, in some cases, heart problems. When accelerated growth is present, it is thought to result from the duplication of the IGF1 receptor gene.