Abnormalities detected

Down syndrome results from the presence of an extra copy of chromosome 21 meaning that these patients have three copies of this chromosome (trisomy 21). Down syndrome is the leading cause of intellectual disability and is the most common genetic alteration in humans. Prevalence is estimated at 1 in 750-800 births. The average life expectancy is over 50 years.

The risk of having a child affected by this syndrome increases with maternal age, especially after 35 years of age.

• 1/385 risk at age 35 years
• 1/106 at age 40 years
• 1/30 at age 45 years

Most frequent clinical findings in patients with Down syndrome:

• Intellectual deficit
• Muscular hypotonia (lack of muscle strength)
• Heart problems
• Small stature
• Early aging
• Infertility in men and a severe decrease in fertility in women

Additional information

Ds-int.org – Down Syndrome International

Edwards syndrome (trisomy 18) is a genetic disorder produced by the presence of an extra chromosome 18. It is the second most common autosomal trisomy after Down syndrome.

The prevalence is estimated at 1 in 6,000 births. Life expectancy is limited: mortality is around 60% in the first week of life and reaches 94-95% between the first and second year of life. Babies with Edwards may have a number of serious medical problems for which they require specialized care.

Similar to Down syndrome, Edwards syndrome is more frequent in mothers with advanced age: after 35 years the incidence progressively increases from 1/2,500 live births at age 36 years to 1/500 at age 43 years.

Most frequent clinical findings in patients with Edwards syndrome:

• Small head
• Low birth weight
• Neonatal hypotonia followed by hypertonia
• Delayed growth
• Congenital heart defects
• Craniofacial anomalies
• Neurological problems

Additional information

Internationaltrisomyalliance.com – International Trisomy 13/18 Alliance

Orpha.net – The portal for rare diseases and orphan drugs

Patau syndrome (Trisomy 13) is a genetic disorder caused by the presence of an extra chromosome 13. It is the least common but the most serious of the viable chromosomal trisomies.

The prevalence is estimated at 1 in 12,000 births.

Life expectancy is limited, with an average 2.5 day survival rate. Ninety percent of infants die before they reach their first year. Many of the fetuses affected by the syndrome die before they are born (spontaneously miscarry). Babies with Patau syndrome suffer from multiple serious malformations resulting in profound physical and mental damage which causes the high mortality rate.

Most frequent clinical findings in patients with Patau syndrome:

• Cleft lip
• Cranial malformations
• Cardiac and renal malformations
• Delayed growth
• Profound intellectual deficit

Additional information

Internationaltrisomyalliance.com – International Trisomy 13/18 Alliance

Orpha.net – The portal for rare diseases and orphan drugs

Turner syndrome is associated with the total or partial absence (complete or partial monosomy) of chromosome X. Even though patients with Turner syndrome only have one normal X chromosome, all of them are women.

The prevalence is between 1/2000 to 1/5000 live female births. Around 1% of all conceptions present with monosomy X. Of these, the majority end in spontaneous abortion, generally during the first week of pregnancy. There is a reduced life expectancy.

Most frequent clinical findings in patients with Turner syndrome – 45,X0)

• Short stature
• Birth with a low hairline at the back of the neck
• Thyroid hormone deficiency (hypothyroidism)
• High arterial pressure (hypertension)
• Renal problems
• Congenital heart defects
• Breast underdevelopment
• Skeletal anomalies
• Increased weight

The majority of women with Turner syndrome have normal intelligence.

Additional information

Tsint.org – Turner Syndrome International

Orpha.net – The portal for rare diseases and orphan drugs

Klinefelter syndrome only occurs in males and results from the presence of an extra chromosome X.
The prevalence is estimated at 1 in 500-1000 male births. Life expectancy is normal.
Most frequent clinical findings in patients with Klinefelter syndrome – 47,XXY

• Infertility
• Increased breast tissue
• Above average height
• Reduction in muscular mass
• Feminine body fat distribution
• Small testicles

Additional information

Aaksis.org – American Association for Klinefelter Syndrome Information and Support (AAKSIS)

Orpha.net – The portal for rare diseases and orphan drugs

Patau syndrome (Trisomy 13) is a genetic disorder caused by the presence of an extra chromosome 13. It is the least common but the most serious of the viable chromosomal trisomies.

The prevalence is estimated at 1 in 12,000 births.

Life expectancy is limited, with an average 2.5 day survival rate. Ninety percent of infants die before they reach their first year. Many of the fetuses affected by the syndrome die before they are born (spontaneously miscarry). Babies with Patau syndrome suffer from multiple serious malformations resulting in profound physical and mental damage which causes the high mortality rate.

Most frequent clinical findings in patients with Patau syndrome:

• Cleft lip
• Cranial malformations
• Cardiac and renal malformations
• Delayed growth
• Profound intellectual deficit

Additional information

Internationaltrisomyalliance.com – International Trisomy 13/18 Alliance

Orpha.net – The portal for rare diseases and orphan drugs

Trisomy of chromosome X, also known as triple X syndrome, is the most common female trisomy and has a variable phenotype caused by the presence of an extra chromosome X.

The prevalence is estimated at 1 in 1000 female births. Life expectancy is normal.

Most frequent clinical findings in patients with 47, XXX syndrome:

Triple X syndrome does not normally present with unusual physical characteristics or medical problems, although women with this condition are often taller than average.

However, there are exceptional cases in which various symptoms have been reported such as:

• Weak muscle tone
• Folds in the upper eyelid
• Seizures
• Renal and genitourinary anomalies
• Delays in the motor system and language, possible cognitive deficits and problems with learning
• Emotional and behavioral difficulties (attention deficit disorder, anxiety, depression)

Additional information

Orpha.net – The portal for rare diseases and orphan drugs