association heterotaxy-multiple midline anomalies
Synopsis
polyhydramnios
multiple congenital anomalies
multiple defects of blastogenesis
- midline anomalies
- asplenia
- abnormalities of laterality formation (heterotaxy)
- hypoplastic, symmetrically unilobate lungs
- bilateral hyparterial bronchi (more consistent with polysplenia)
- abdominal situs inversus
- midline stomach
- symmetric liver
- left gallbladder
- azygous continuation of the inferior vena cava
multiple defects
- bronchoesophageal fistula
- duodenal atresia
- absence of posterior leaf of diaphragm
- horseshoe adrenal gland
- microcephaly
- Dandy-Walker anomaly with agenesis of cerebellar vermis and occipital encephalocele
- holoprosencephaly with orbital encephalocele
- midline defect of the orbital plate of the skull
- bilateral anophthalmia
- double proboscis with bilateral choanal atresia
- midline upper lip and palatal cleft
- single-lobed thyroid
- hypoplastic external genitalia with midline cleft of scrotum
- long tapering fingers
- defects of the cranium at the sites of orbital and occipital encephaloceles
Physiopathology
Defects of laterality frequently are associated with other complex midline anomalies, which both result from a disturbance of pattern formation during blastogenesis, i.e., the induction of the progenitor fields.
The latter are the result of the establishment of upstream expression domains of growth and transcription factors and other morphogens. Many of these and other genetic systems, expressed asymmetrically around the midline, are responsible for laterality formation and are the result of upstream and subsequent downstream gene expression cascades through the expression of genes such as HOX genes; bFGF; transforming growth factor beta/activins/BMP4; WNT-1,8; and SHH.
See also
References
Gilbert-Barness E, Debich-Spicer D, Cohen MM Jr, Opitz JM. Evidence for the "midline" hypothesis in associated defects of laterality formation and multiple midline anomalies. Am J Med Genet. 2001 Jul 15;101(4):382-7. PMID: 11471162