Trisomy 13

At a glance

This chromosomal disorder is characterized by specific midline dysmorphic features and organ malformations. Usually leading to death before 6 months of life.

Synonyms

Patau Syndrome; Bartholin-Patau Syndrome; Trisomy D (Trisomy 13s).

History

First described by Thomas Bartholin in 1657, but recognized as a clinical syndrome when the trisomy etiology was discovered by Klaus Patau in 1960.

Incidence

1:4,000 to 1:10,000 live births. Age of onset: newborn. Risk factors include advanced age of mother. Sex distribution is equal.

Genetic inheritance

In 75% of cases, it is manifested by a trisomy of chromosome 13, caused by meiotic nondisjunctions (“free”). Reciprocal translocations (20% of cases) are also present and either associated with de novo or familial translocation with a recurrence rate of 5 to 15%. The presence of mosaicism (5%) is a result of postzygotic (postfertilization) mitotic nondisjunction; however, it is less severe than full trisomy 13, but quite variable.

Pathophysiology

A single defect during the first 3 weeks of development of the prechordal mesoderm can lead to morphologic defects of the midface, eyes, and forebrain, as well as induction defects on the prosencephalon (cerebral hemispheres, diencephalon, hypothalamus, thalamus), leading to holoprosencephaly.

Diagnosis

Diagnosis can be evocated by the characteristic features, including microcephaly, microphthalmia, hypertelorism, cleft lip or palate, polydactyly, cardiovascular (ventricular septal defect [VSD], cardiomyopathy, dextroposition), and genitourinary and neurological abnormalities. It is confirmed by karyotype. Median survival is 7 days although survival into adulthood is possible.

Clinical aspects

This severe disease is most often associated with midline defects: mental retardation with head malformations (microcephaly; cranial asymmetry; arhinencephaly; holoprosencephaly; cerebellar malformations; corpus callosum agenesis; neural tube defects; anencephaly; spinal dysraphism; seizures; sloping forehead; wide sagittal suture and fontanels; cebocephaly; premaxillary agenesis; scalp defects; dysplastic low-set ears; microphthalmia; hypertelorism or hypotelorism; coloboma; retinal dysplasia orbital; cyclopia; choanal agenesis; cleft lip or palate) and skeleton anomalies (polydactyly of the fingers and toes, ectrodactyly, valgus deformity, spina bifida, hyperconvex narrow fingernails) are also observed. Abdomen and pelvis (Meckel diverticulum; intestinal malrotation; mobile cecum; hypoplastic penis and scrotum; cryptorchidism; bicornis uterus; microcystic and hyperlobulated kidneys; megaureter; hydronephrosis; umbilical hernia; and single umbilical artery) and thoracic organs (atrial septal defect, ventricular septal defect, coarctation of the aorta, bicuspid aortic valve, bilobed lung) are also involved. Apnea, feeding difficulty, and deafness are common.

Precautions before anesthesia

Evaluate cardiac function (clinical, echocardiography, ECG), renal function (echography, CT, urea, creatinine, electrolytes), and neurological function (clinical, CT scan, MRI, EEG).

Anesthetic considerations

Direct laryngoscopy and tracheal intubation can be difficult (face, mouth, and neck anomalies); the use of ...