trisomy 13

Trsiomy 13 is the least common and the most severe of the viable autosomal trisomies.

Synopsis

 craniofacial anomalies

• microcephalia
• receding forehead
• epicanthal folds
• sparse curled eyelashes

• midline scalp defects at vertex (cutis aplasia)
• horizontal palpebral fissures
• broad and flat nose
• abnormal ears
  • low-set ears
  • flat ears
  • poorly defined ears
  • microtia

• ocular anomalies
  • microphthalmia
  • anophthalmia
  • deep-set eyes
  • cataract
  • corneal opacities
  • retinoschisis
  • hypoplasia of optic nerve
  • persistent hyperplastic primary vitreous
  • coloboma of iris or retinal coloboma
  • aniridia
  • retinal dysplasia
  • retinoblastoma

• hypotelorism
• incisor teeth present at birth

• midline facial defects
  • cleft lip / cleft palate
  • absent or malformed nose or proboscis

 cardiovascular malformations (80%)

• patent ductus arteriosus
• atrial septal defect
• ventricular septal defect
• dextrocardia (cardiac dextroposition)

 cerebral anomalies

• holoprosencephaly
• microcephaly
• heterotopia of striated skeletal muscle and glial tissue in pontine leptomeninges (6548367)

 splenopancreatic field abnormality

• splenopancreatic fusion
  • ectopic splenic tissue in the cauda pancreatis
  • ectopic pancreatic tissue in the spleen or accessory spleen
  • fusion of the cauda pancreatis and splenic hilum

 urinary anomalies

• polycystic kidneys (micromulticystic kidneys)
• renal malformations
• renal duplication
• urteral duplications
• hydronephrosis and hydroureters
• bilateral nephrogenic rests (nephroblastomatosis) (16177880)
  • loss of Wilms’ tumor gene 1 (WT1) transcript and a biallelic expression of insulin growth factor 2 (IGF2) (16177880)

 male genital anomalies

• cryptorchidism
• scrotal anomalies
• Leydig cell hypoplasia
• testicular agenesis

 female genital anomalies

• bicornuate uterus
• clitoridal hyperplasia
• double vagina

 omphalocele
 hernias

 skeletal anomalies

• hypoplastic 12th ribs
• 12th ribs agenesis
• hypoplastic pelvis with flattened acetabular angle
• kyphoscoliosis

 limb anomalies

• prominent calcaneum
• rocker-bottom feet
• postaxial polydactyly of hands or feet (hexadactyly)
• talipes equinovarus
• talipes calcaneovalgus
• flexed fingers
• retroflexed thumbs
• clinodactyly of little fingers
• camptodactyly
• narrow and hyperconvex nails
• dermatoglyphic anomalies
  • distal axial triradius
  • single palmar crease (simian line)
  • arch fibular or arch fibular 5 pattern

 capillary hemangiomas (face, forehead, nape of neck)
 hematologic anomalies

• multiple projections in neutrophilic nuclei
• increased fetal hemoglobin (HbF)
• increased Gower-2 hemoglobin

Etiology

 nondisjunction during maternal meiosis

• a significant association exists between Patau syndrome and increased maternal age

See also

 trisomies

• trisomy 18 (Edwards syndrome)