The author stresses the importance of genetic testing prior to deciding a prognosis for affected patients. She also proposes prenatal screening and evaluation in cases at risk for development of situs ambiguus. Recent studies have shown higher rates of heterotaxy syndrome among Hispanic infants of Mexican descent, as well as female infants of non-Hispanic black and white mothers. Additional studies must be done to clarify the mechanisms behind racial disparities in heterotaxy syndrome. Individuals of Asian descent show a higher prevalence of heterotaxy syndrome in general than members of the Western world.The National Birth Defects Prevention study (October 2014) attempted to link clinical presentations of situs ambiguus to demographics in an epidemiological study. This proved a difficult task due to the vast differences in presentation of this disorder. However, the authors are hopeful that finding a link can help inform clinical decision-making, predictive analyses, and future outcomes. See also
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radio/639 at eMedicine
Patient are characterized by: hypertelorism, a wide nasal bridge, a split nasal tip, a broad columella (strip of skin running from the tip of the nose to the upper lip), widely separated narrow nostrils, a long philtrum (vertical groove on the upper lip) and two-sided nasal swellings.Frontorhiny is one of the two subtypes of FND where a genetic mutation has been determined. The mutation has an autosomal recessive inheritance pattern. The syndrome is often seen in siblings and, most of the time, parents are carriers. See Genetics. Craniofrontonasal dysplasia
Craniofrontonasal dysplasia (CFND) is a rare type of FND with X linked inheritance. Multiple features are characteristic for CFND such as craniosynostosis of the coronal sutures (prematurely closed cranial sutures), dry frizzy curled hair, splitting of the nails and facial asymmetry.There is a large variety in phenotype. Women present with a more severe phenotype than men. Females characteristically have FND, craniosynostosis and additional small malformations. Males are usually more mildly affected, presenting with only hypertelorism. The gene that causes CFND is called EFNB1 and is located on the X chromosome. A hypothesis for the more severe outcome in females is based on X-inactivation, which leads to mosaicism. As a result, patients have less functional cells, generating abnormal tissue boundaries, termed "cellular interference". This process almost never occurs in males, as they have less mutagenic material in their genes. EFBN1 also has an important function in males. As the syndrome has an X-linked inheritance pattern, there is no man-to-man inheritance.