Last Updated on December 16, 2021 by
The Patau syndrome is a congenital disease of genetic origin, due to the presence of trisomy on chromosome 13 (Rebate Molina, Uriel Ramos, and sources, 2010).
Specifically, Patau syndrome is the third most frequent autosomal trisomy, after Down syndrome and Edwards syndrome (Fogu et al., 2008).
At the clinical level, this pathology affects multiple systems. Thus, various alterations and anomalies in the nervous system, generalized growth retardation , cardiac, renal and musculoskeletal malformations appear (Ribate Molina, Uriel and Ramos fuentes, 2010).
The diagnosis is usually made during pregnancy in most cases, since clinical findings can be detected in routine ultrasounds (Ramos Fuentes, 2016).
Patau Syndrome Symptoms
However, to rule out false positives and erroneous diagnoses, several genetic tests are usually performed to identify trisomy 13 (Ribate Molina, Uriel and Ramos fuentes, 2010).
As for treatment, there is currently no cure for Patau syndrome, the survival of those affected usually does not exceed one year of life. The most common causes of death are cardiorespiratory complications (Ramos Fuentes, 2016).
Characteristics of Patau syndrome
Patau syndrome, also known as trisomy 13, is a medical pathology of genetic origin that is associated with severe intellectual disability as well as multiple physical disorders (Genetics Home Reference, 2016).
Affected individuals usually present with serious cardiac anomalies, diverse alterations in the nervous system, musculoskeletal malformations, facial alterations, muscular hypotonia, among others (Genetics Home Reference, 2016).
Due mainly to the serious multisystemic affectation, people affected by the Patau syndrome usually present a very reduced life expectancy (Best, 2015).
This syndrome was initially identified in 1960, as a cytogenetic syndrome, that is, a genetic disorder associated with a chromosomal anomaly (Best, 2015).
Chromosomes make up the genetic material of the cells that make up our body. Specifically, chromosomes are constituted by deoxyribonucleic acid, also known by its acronym DNA, also has a composition characterized by the presence of different protein substances .
These chromosomes are usually organized structurally in pairs. In the case of humans, we present 23 pairs of chromosomes, having in total 46 of these.
In the case of Patau syndrome, the genetic anomaly affects chromosome 13 specifically. Affected people have a trisomy of chromosome 13, that is, they have three copies of it.
At a more specific level, each ovum and each sperm contain 23 chromosomes each, with the genetic material of the maternal and paternal parent (Stanford Children’s Health, 2016).
At the time of fertilization, the union of both cells results in the creation of 23 chromosomal pairs, or what is the same, the presence of 46 chromosomes in total (Stanford Children’s Health, 2016).
However, there are occasions in which an error or an event altered during the union, leads to the presence of genetic anomalies, such as the presence of an extra chromosome in one of the pairs (Stanford Children’s Health, 2016).
In this way, this altered process will cause a succession of neurobiological events during fetal development, which will alter the normal or expected gene expression , giving rise to the presence of organic involvement in various systems.
Statistics
Patau syndrome or trisomy 13 is considered a rare or rare disease. Different investigations estimate that this pathology presents an approximate frequency of 1 case per 5,000-12,000 newborns (National Organization for Rare Disorders, 2007).
Despite this, in most of the cases the gestation of those affected by the Patau syndrome does not usually come to term, so the frequency can increase significantly (National Organization for Rare Disorders, 2007).
Thus, it has been observed that the annual rate of spontaneous abortions in this pathology is high, representing approximately 1% of the total of these (Ramos Fuentes, 2016).
Regarding the distribution of Patau syndrome by sex, it has been observed that this pathology affects women more frequently than men (Genetics Home Reference, 2016).
Characteristic signs and symptoms
Clinically, Patau syndrome can affect very heterogeneously in the body and between different cases, so it is difficult to establish what are the cardinal signs and symptoms of this disease.
However, different clinical reports such as that of Ribate molina, Puisac Uriel and Ramos Fuentes (2010), highlight which are the most frequent clinical findings in those affected by Patau syndrome or trisomy 13:
Alteration of growth
The presence of a generalized growth retardation is one of the most frequent clinical findings. Specifically, slow or delayed growth in the prenatal and postnatal stages can be observed in approximately 87% of cases of Patau syndrome.
Alterations and malformations in the central nervous system (CNS)
In the case of the nervous system, there are several clinical findings that can be observed: hypotonia / hypertonia, apnea crisis, holoprosencephaly, microcephaly, psych0m0tor retardation or severe intellectual disability.
- Hypotonia / muscle hypertonia : the term hypotonia refers to the presence of muscle flaccidity or reduced muscle tone , while the term hypertonia refers to the presence of an abnormally high muscle tone. Both medical events occur in 26-48% of affected individuals.
- Crisis or episodes of apnea : episodes of apnea usually occur in approximately 48% of cases and consist of a reduction or paralysis of the breathing process for a short period of time.
- Holoprosencephaly: this term refers to the presence of different malformations at the cerebral level, affecting mainly the most anterior portion. This clinical finding can be observed in approximately 70% of cases of Patau syndrome.
- Microcephaly : about 86% of those affected have a lower cranial perimeter than expected for their sex and maturational level .
- Psych0m0tor delay : As a result of the various physical malformations, individuals suffering from Patau syndrome will present serious difficulties in coordinating and executing all types of motor acts. This finding can be observed in 100% of cases.
- Severe intellectual disability : cognitive impairment and severe intellectual disability is a clinical finding present in all cases diagnosed with Patau syndrome. Both neurological conditions develop as a result of the extensive involvement of the nervous system.
Alterations and craniofacial malformations
At the facial and cranial level, there are also several clinical signs and symptoms that can be observed:
- Flattened front : the abnormal development of the frontal part of the skull is a present sign in all cases of Patau syndrome.
- Ocular disorders : in the case of abnormalities and pathologies that affect the eyes, they are present in approximately 88% of cases, the most frequent being microphthalmina, iris coloboma or ocular hypotelorism.
- Various malformations in the auricular pavilion : the progression of facial and cranial anomalies can also affect the auricle in 80% of cases.
- Cleft lip and cleft palate : both oral malformations are present in approximately 56% of affected individuals. The term “cleft” refers to the presence of an incomplete closure of the lips, showing a fissure in the medial area, while the term ” cleft palate” refers to an incomplete closure of the entire structure that makes up the palate or roof of the mouth .
Musculoskeletal malformations
Musculoskeletal abnormalities and malformations can affect various areas, the most common being the neck and extremities.
- Neck : the anomalies that affect this particular area are present in most of the cases, specifically a short or underdeveloped neck can be observed in 79% of those affected, while an excess of skin in the neck is present in the neck. % of the cases.
- Extremities : the alterations that affect the extremities are diverse, it is possible to observe polydactyly in 76% of those affected, fingers flexed or superimposed in 68%, grooves in the hands in 64%, or hyperconvex nails in 68% of the affected.
Alterations of the cardiovascular system
The anomalies related to the cardiovascular system, constitute the most serious medical condition in the Patau syndrome, since it seriously threatens the survival of those affected.
In this case, the most frequent findings are intraventricular communication in 91%, persistence of ductus arteriosus in 82%, and interventricular communication in 73%
Alterations of the genitourinary system
The manifestations of the genitourinary system are usually related to the presence of cryptorchidism in males, polycystic kidney, bicornuate uterus in women and hydronephrosis.
Causes
As we have pointed out above, Patau syndrome is associated with the presence of genetic abnormalities on chromosome 13.
Most of the cases are due to the presence of three complete copies of chromosome 13, so that the extra genetic material alters the normal development and, therefore, giving rise to the characteristic clinical course of the Patau syndrome (Genetics Home Reference, 2016).
However, there are also cases of Patau syndrome due to duplications of parts of chromosome 13. It is possible that some affected people have all intact copies of this and an extra adhered to another different chromosome (Genetics Home Reference, 2016).
In addition, cases have also been reported in which individuals only have this type of genetic alteration in some cells of the body. In this case, the pathology acquires the name of trisomy 13 in mosaic, and therefore the presentation of the signs and symptoms will depend on the type and number of cells affected (Genetics Home Reference, 2016).
Diagnosis
People affected with Patau syndrome present a set of clinical manifestations that are present from the moment of birth.
Based on the observation of the signs and symptoms, it is possible to make a clinical diagnosis. However, when there is suspicion, it is essential to perform other complementary tests to confirm the presence of Patau syndrome.
In these cases, the tests of choice are genetic tests of the karyotype, these are able to give us information about the presence / absence of an extra copy of chromosome 13.
In other cases, it is also possible to perform the diagnosis in the prenatal stage, performing routine ultrasounds may show alarm indicators , so, in general, genetic @nalyzes are requested to confirm their presence.
The most common tests in the prenatal stage are fetal ultrasound, amniocentesis and chorionic villus sampling (National Organization for Rare Disorders, 2007).
In addition, once the definitive diagnosis of Patau syndrome has been made, whether in the prenatal or postnatal phase, it is essential to carry out a continuous medical follow-up in order to detect early the possible medical complications that put at risk the survival of the affected person (National Organization for Rare Disorders, 2007).
Treatment
At present, there is no specific or curative treatment for Patau syndrome, therefore, therapeutic interventions will be directed towards the treatment of medical complications.
Due to the serious multisystemic affectation, people affected by the Patau syndrome will require medical assistance from the moment of birth (Ramos Fuentes, 2016.
On the other hand, cardiac and respiratory alterations are the main causes of death, therefore, it is essential to follow-up and detailed medical treatment of both conditions (Ramos Fuentes, 2016).
In addition to the pharmacological intervention for different signs and symptoms, it is also possible to use surgical procedures to correct some malformations and musculoskeletal abnormalities.
Also Read: Cerebral Hemispheres: Functions and Parts
In summary, the treatment of Patau syndrome or trisomy 13 will be specific depending on each case and the associated clinical course. Generally, the intervention usually requires the coordinated work of different specialists: pediatricians, cardiologists, neurologists, etc. (National Organization for Rare Disorders, 2007).
