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Patau Syndrome

Trisomy 13

Patau syndrome (Trisomy 13) is a genetic disorder caused by an extra copy of chromosome 13, characterized by mental retardation and defects to the central nervous system and heart.


Presentation

The signs of Patau syndrome become evident at birth. Although microphthalmia, cleft palate and polydactyly constitute the classic triad of trisomy 13 [8], not all three signs are present in all cases of Patau syndrome. The neonate presents with variable physical defects, and upon further assessment, cardiac, neurological, renal and ocular anomalies. Some of these anomalies are listed here [5] [8] [9] [10]:

Craniofacial defects

Limb defects

Heart defects

CNS abnormalities

Ocular abnormalities

Renal anomalies

Genitalia anomalies

These clinical findings at birth are indicative of Patau syndrome. However, diagnosis must only be made when trisomy 13 is evident on karyotyping. Parents who opt for screening of fetal chromosomal defects can find if the fetus has an extra chromosome 13 before birth. They, then, have the option of continuing or terminating the pregnancy.

The clinical signs of Patau syndrome are similar to those of Edwards syndrome [8]. Care must be taken, as this similarity often leads to misdiagnosis.

Fishing
  • The karyotype was found to be 46, XY, der(18)t(13;18) (q32;p11.32) pat confirmed by fluorescence in situ hybridisation (FISH). A review of earlier studies showed that features of trisomy 13 are found in cases of duplication of bands 13q14 to qter.[ncbi.nlm.nih.gov]
  • FISH To perform AneuVysion FISH following a standard protocol (Abbott Molecular, Des Plaines, IL), 5 mg of the original CV sample and 5 ml of amniotic fluid were used.[oadoi.org]
  • The derivatives (13) present in the three cell lines were characterized through fluorescence in situ hybridization (FISH) experiments with suitable probes; the results suggested a sequence of rearrangements which beginning from an isochromosome (13q)[ncbi.nlm.nih.gov]
  • Causes for Rejection Frozen specimen, inappropriate container Turnaround Time FISH: 24 hours Cytogenetic analysis: 7-10 days[cytogenx.com]
Multiple Congenital Anomalies
  • Trisomy 13 or Patau syndrome (PS) is a chromosomal disorder characterized by a well known presentation of multiple congenital anomalies. Our objective was to determine the clinical features and prognosis observed in a sample of patients with PS.[ncbi.nlm.nih.gov]
  • Entry H01562 Disease Name Patau syndrome; Trisomy 13 Description Patau syndrome, also known as trisomy 13, is a chromosomal disorder characterized by the severe clinical picture of multiple congenital anomalies.[genome.jp]
  • Wagner: Multiple congenital anomaly caused by an extra autosome. The Lancet, London, 1960, I: 790. What is an eponym? An eponym is a word derived from the name of a person, whether real or fictional.[whonamedit.com]
  • Trisomy 13 is a severe syndrome with multiple congenital anomalies and a poor prognosis. Of the rare fetuses that survive to term, most die in the first week of life and 5% survive to 6 months of age.[clinicaladvisor.com]
  • Available from: Incidence of Patau syndrome More Details (Trisomy 13) is 1/5000 births and it is the most severe of the three autosomal trisomies that can lead to live born infants. [1] This syndrome is characterized by multiple congenital anomalies involving[ijri.org]
Short Hands
  • The most common physical signs for Patau Syndrome are the decreasing of muscle tone, small hands, small ears, small head and mouth, as well as wide and short hands with short fingers.[en.wikipedia.org]
Bulbous Nose
  • Some of these anomalies are listed here: Craniofacial defects Scalp defects Low-set ears Cleft lip Cleft palate Bulbous nose Hypotelorism Micrognathia Limb defects Polydactyly Rocker-bottom feet Single palmar crease Heart defects Patent ductus arteriosus[symptoma.com]
Thin Lips
  • The 8 year old white male presented with psychomotor retardation, tethered cord, soft, fleshy ears, and normal facial features except for thin lips.[ncbi.nlm.nih.gov]
Neurologic Manifestation
  • The neurological manifestations are severe with hypotonia and hyporeactivity with an apparent lack of awareness of surroundings.[orpha.net]
Myoclonic Jerking
  • We also recorded non-epileptic myoclonic jerks in one patient known to suffer from epileptic spasms.[ncbi.nlm.nih.gov]

Workup

The clinical diagnosis of Patau syndrome is made either prenatally or at birth. In both cases, evidence of trisomy 13 on cytogenetic analysis is a sure diagnosis of Patau syndrome.

Prenatally, cytogenetic analysis can be done using chorionic villous sampling (10-13 weeks' gestation) or amniocentesis (15 weeks' gestation or later). Non-invasive methods like cfDNA from maternal blood are highly sensitive and specific, and therefore, promising [11].

After birth, conventional cytogenetic or FISH (Fluorescence in Situ Hybridization) studies can show trisomy 13. FISH can describe some chromosomal anomalies more accurately.

A cytogenetic analysis may reveal free trisomy 13, partial trisomy 13 or Robertsonian translocation [7]. Free trisomy 13 rarely recurs. However, the latter two variants have a high risk of recurrence, and therefore, should be followed with cytogenetic analysis of parents. Genetic counseling should be recommended to parents with high risk of recurrence.

A neonate with Patau syndrome requires detailed workup to evaluate the severity of the condition. All systems, especially CNS and heart, should be assessed through metabolic workup and imaging studies.

Photoparoxysmal Response
  • METHODS: All EEGs, case-notes, cytogenetic diagnosis and neuroimaging when available were reviewed; data on the occurrence of seizures, epileptiform discharges, photoparoxysmal response and their characteristics in terms of positive frequencies, latencies[ncbi.nlm.nih.gov]

Treatment

Patau syndrome, like other trisomies, has no treatment. Therapy aims to support defective organs of the body, prevent complications and prolong survival of the neonate.

Parents of such children should be recommended psychological therapy and genetic counseling. They should also be connected to support groups, comprising of other parents whose children also suffered from Patau syndrome [8].

Prognosis

Patau syndrome, like other trisomies, has no treatment. Therapy aims to support defective organs of the body, prevent complications and prolong survival of the neonate. Despite that, the prognosis remains poor.

Median survival age for children with Patau syndrome is less than 3 days. Those who do survive for longer time exhibit severe mental retardation and developmental delays [8] [9].

Etiology

Patau syndrome is a genetic disorder, caused by presence of three copies of chromosome 13, instead of normal two.

Epidemiology

Patau syndrome is rare, with the incidence of about 1-2 cases from 10,000 births. It is the third most frequent trisomy among live births [1]. Like other trisomies, it is linked to maternal age [1] [2]. Significant bias on basis of race or ethnicity is not evident.

Patau syndrome is associated with a high rate of spontaneous abortion, intrauterine death, and a very short life span [3] [4]. Only 5% to 10% of neonates survive past the first year [3].

Gender: Males have a decreased prognosis of survival compared to females, both at birth and later in life [5] [6].

Age: Patau syndrome is a congenital syndrome, and is present prenatally. It may be diagnosed prenatally or at birth.

Sex distribution
Age distribution

Pathophysiology

The most frequent form of Patau syndrome is free trisomy 13 [7], in which all cells of the neonate contain an extra copy of chromosome 13. In a rarer type of trisomy 13, called mosaic trisomy 13, some cells of the neonate’s body contain three copies of chromosome 13, while some are normal.

Robertsonian translocation of chromosome 13 to another chromosome constitutes of the third and the rarest type of trisomy 13 found in neonates with Patau syndrome.

Prevention

There is no guideline for the prevetion of Patau syndrome.

Summary

Patau syndrome, more specifically known as trisomy 13, is a severe condition of newborns who have an extra copy of chromosome 13. It is characterized by structural defects, poor neurological performance, heart anomalies and other conditions at birth. Although rare compared to other trisomies, it is untreatable and holds a poor prognosis for the newborn.

Patient Information

Patau syndrome is a genetic defect that presents at birth as physical, neurological, cardiac, ocular, renal and genital defects due to an extra copy of chromosome 13. It is very rare. It is not an inherited disease, although some of its variants have a higher risk of recurrence. Prognosis is very poor, as many children are stillborn or die within few days of birth. There is no cure for a child with Patau syndrome, but you can prevent recurrence by prenatal screening and karyotyping of future children at fetal stage.

What are the symptoms of Patau syndrome?

The symptoms are always present at birth. Children with Patau syndrome suffer from severe mental retardation, heart defects, physical deformities and other problems that make their bodies incompatible to survive. Physically, they may exhibit:

These three signs make up the triad of Patau syndrome. However, it should be noted that all three signs may not be present in a child suffering from Patau syndrome.

What causes this disorder?

Patau syndrome is caused by an extra copy of chromosome 13. A normal human has 23 pairs of chromosomes, i.e. only two copies of chromosome 13. A child with Patau syndrome, however, has three copies of chromosome 13 (trisomy 13).

The most common variant of trisomy 13 is free trisomy 13. Like the name suggests, the extra chromosome is not attached to another, and is present in all cells of the child. This is the most severe variant of Patau syndrome, but has a very low risk of recurrence.

The less severe variants are partial trisomy 13 and Robertsonian translocation. In partial trisomy 13, not all cells of the child have three copies of chromosome 13 while in Robertsonian translocation, only a part of the extra chromosome 13 is present as an attachment to another chromosome. Although both these variants are less severe, they have more risk of recurrence. Hence, if your child has been diagnosed with one of these two variants, there’s a high chance that your next child may also suffer from Patau syndrome.

How is it diagnosed?

Patau syndrome is diagnosed through:

  • Physical exam – Your doctor will perform a physical examination of your child. Most signs are evident on physical exam. However, your doctor will recommend further tests before giving a final diagnosis of Patau syndrome. 
  • Genetic test – Genetic testing is a definite way to diagnose the syndrome. It allows the doctor to analyze your child’s DNA. Depending on the results of this test, your doctor may recommend a genetic test to you and your partner.
  • Once the diagnosis is confirmed, your doctor may recommend further tests to assess the severity of your child’s condition.
  • Blood tests – Since the body of a child suffering from Patau syndrome is incompatible with life, the blood tests will help your doctor to keep a check on your child’s body. The tests will show any problem that threatens the life of your newborn, and will enable your doctor to address it appropriately. 
  • Imaging studies – A child suffering from Patau syndrome does not only have physical malformations. There may be problems present inside the body, hidden from your eye. X-rays, CT scans and MRIs will help assess the condition of the internal organs of your child’s body.

What are the treatments for this disease?

There is no treatment available for Patau syndrome. Many children die before, or within a few days of birth. If your child has been diagnosed with Patau syndrome before delivery, you may choose to continue or terminate the pregnancy. Survivors suffer from severe mental retardation and health problems all their lives.
If your child had a free trisomy 13, it is rare that your next child would also suffer from Patau syndrome. However, if your child had one of the other two variants, i.e. partial trisomy 13 or Robertsonian translocation, the risk of your next child suffering from the same is high.

In the latter case, your doctor will recommend genetic testing and counseling for you and your partner. This will help you assess the risk, and prevent recurrence of Patau syndrome in your next pregnancy.

There are support groups for parents whose children had suffered from Patau syndrome. These may be helpful in reducing your anxiety and depression. Genetic counseling will help you get more information, and make an informed decision about your current or future pregnancies.

References

Article

  1. Savva GM, Walker K, Morris JK. The maternal age‐specific live birth prevalence of trisomies 13 and 18 compared to trisomy 21 (Down syndrome). Prenat diag. 2010; 30:57-64.
  2. Bugge M, Collins A, Hertz JM, et al. Non-disjunction of chromosome 13. Hum Molec Genet. 2007;16(16)
  3. Rasmussen SA, Lee-Yang CW, Quanhe Y, et al. Population-based analyses of mortality in trisomy 13 and trisomy 18. Pediatrics. 2003;111(4)
  4. Lakovschek IC, Streubel B, Ulm B. Natural outcome of trisomy 13, trisomy 18, and triploidy after prenatal diagnosis. Am J Med Genet Part A. 2011; 155: 2626–2633.
  5. Crider KS, Olney RS, Cragan JD. Trisomies 13 and 18: population prevalences, characteristics, and prenatal diagnosis, metropolitan Atlanta, 1994-2003. Am J Med Genet A. 2008; 146A(7):820-6.
  6. Baty BJ, Blackburn BL, Carey JC. Natural history of trisomy 18 and trisomy 13: I. Growth, physical assessment, medical histories, survival, and recurrence risk. Am J Med Genet. 1994; 49(2):175-88.
  7. Caba, L, Rusu C, Butnariu L et al. Phenotypic variability in Patau syndrome. Revista medico-chirurgicala a Societatii de Medici si Naturalisti din Iasi. 2012; 117(2):321-327.
  8. Plaiasu V, Ochiana D, Motei G, Anca I, Georgescu A. Clinical relevance of cytogenetics to pediatric practice. Postnatal findings of Patau syndrome - Review of 5 cases. Maedica (Buchar). 2010; 5(3):178-85.
  9. Baty BJ, Jorde LB, Blackburn BL, Carey JC. Natural history of trisomy 18 and trisomy 13: II. Psychomotor development. Am J Med Genet. 1994; 49(2):189-94.
  10. Pont SJ, Robbins JM, Bird TM, et al. Congenital malformations among liveborn infants with trisomies 18 and 13. Am J Med Genet A. 2006; 140(16):1749-56.
  11. Palomaki GE, Kloza EM, Lambert-Messerlian GM et al. DNA sequencing of maternal plasma to detect Down syndrome: an international clinical validation study. Genet Med. 2011; 13: 913–920

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Last updated: 2019-07-11 22:04