Fetal Alcohol syndrome (FAS)

What is Fetal Alcohol syndrome (FAS)?

Fetal Alcohol syndrome is caused when a fetus is exposed to alcohol during the pregnancy. It causes damage to both growth and brain development.

Characteristics of the syndrome include distinct and unique facial features, a short stature, low weight at birth and continued low growth, as well as issues with coordination, learning and development.

Syndrome Synonyms:
Acetaldehyde Dehydrogenase 2 Alcohol Aldehyde Dehydrogenase 2 Aldh, Liver Mitochondrial FAS

What gene changes cause Fetal Alcohol syndrome (FAS)?

The syndrome is caused by exposure to the fetus to alcohol during pregnancy. The effects are irreversible and may vary in their severity.

Environmental causes, or exposure to external environmental factors, can sometimes contribute to the cause of a rare disease.

What are the main symptoms of Fetal Alcohol syndrome (FAS)?

The main symptoms of the syndrome include a low birth weight and a failure to thrive that affects growth development. Behavioral and learning issues are also a major symptom including hyperactivity, impulsiveness, and anxiety.

Facial and physical characteristics include a short stature, small eye openings, a thin upper lip and smooth philtrum.

Other health conditions may include heart, bone and kidney problems. Issues with vision and hearing, seizures, poor balance and coordination.

Possible clinical traits/features:
Facial flushing after alcohol intake, Reduced acetaldehyde dehydrogenase level

How does someone get tested for Fetal Alcohol syndrome (FAS)?

The initial testing for Fetal Alcohol syndrome can begin with facial analysis screening, through the FDNA Telehealth telegenetics platform, which can identify the key markers of the syndrome and outline the need for further testing. A consultation with a genetic counselor and then a geneticist will follow. 

Based on this clinical consultation with a geneticist, the different options for genetic testing will be shared and consent will be sought for further testing.   

medical information on Fetal Alcohol Syndrome

Most affected infants are of low birth-weight. There is pronounced hypotonia, often a small head, and possibly jitteriness. This is followed by failure to thrive and mild to moderate developmental delay. The facial features consist of mild to moderate microcephaly, short palpebral fissures and a smooth, under-developed philtrum with a thin upper lip. Moore et al., (2002) report detailed anthropometric studies of the facial features. The distal phalanges are small and the fifth fingernail might be dysplastic. The palmar creases are unusual in that there is often a deep extra line running across the palm from the ulnar side towards the gap between the middle and index fingers. Cardiac lesions occur in about a third of cases and the commonest malformation is a VSD, followed by tetralogy of Fallot and an ASD. It has been suggested that renal anomalies might be more common, however, Taylor et al., (1994) did not find a significantly increased incidence of renal anomalies in 84 patients (3.6% had renal anomalies). The kidneys were, however, significantly smaller. Supernumerary nipples may be a feature (Urbani and Betti, 1995). Note that some cases with mitochondrial respiratory chain deficiency can have similar facial features (Cormier-Daire et al., 1997).
Johnson et al., (1996) discussed the central nervous system abnormalities in this condition. These include agenesis of the corpus callosum, cavum septum pellucidum, ventriculomegaly, hypoplasia of the inferior olivary eminences, a small brain stem, and microencephaly. Frontonasal dysplasia and other midline defects may be associated. Swayze et al., (1997) reported MRI studies of 10 patients. Six had some type of midline anomaly ranging from partial to complete callosal agenesis to a hypoplastic corpus callosum or cavum septi pellucidi and cavum vergae. Other abnormalities included microcephaly, ventriculomegaly, and hypoplasia of the inferior olivary eminences.
Stromland (1985, 1990), Chan et al (1991) and Stromland (1996) discuss the ocular malformations seen in children with fetal alcohol syndrome. The most common is optic nerve hypoplasia, occurring in up to half of the cases. Other abnormalities include microphthalmos, cataract, anterior chamber anomalies, strabismus, ptosis, and abnormalities of the retinal vessels. Chan et al., (1991) reported a case with bilateral Peters' anomaly. Note the3 sibs with corneal clouding, said to have fetal alcohol syndrome (Edward et al., 1993). There was dysgenesis of the corneal endothelium.
Punctate calcification of the epiphyses, a cleft lip and palate (Munger et al., 1996) and renal anomalies have all been described. Froster and Baird (1992) presented evidence of limb defects in infants exposed to high alcohol levels in utero. The limb defects were mainly transverse, but two cases had ulnar defects. Pyloric stenosis may be associated (Lodha et al., 2005).
Streissguth and Dehaene (1993) studied fetal alcohol syndrome in twins of alcoholic mothers. They found that the rate of concordance was 5/5 for monozygotic and 7/11 for dizygotic twins. They concluded that there was a genetic component to the expression of the teratogenic effects of alcohol. Riikonen (1994) also reported discordant twins, although nothing is mentioned about zygosity. Haddad and Messer (1994) reported a remarkable family where three sibs had features of the condition. In a prospective Australian study (Elliott et al., 2008), 51% of the cohort had an affected sib.
Astley and Clarren (1996) undertook a stepwise discriminant analysis of features from photographs of patients with fetal alcohol syndrome and concluded that palpebral fissure length, thinness of upper lip and smoothness of philtrum could discriminate between fetal alcohol and other similar syndromes.
Other signs including, ""railroad tract"" configuration of the years ""hockey stick"" palmar creases, limitation of pronation-supernation at the elbows, lack of complete extension of one or more of the digits (and at other joints), have been commented upon (Jones et al., 2010).
CNV analysis of 95 children with fetal alcohol spectrum disorder and 87 age-matched controls was performed by Zarrei et. al. (2018). In 12/95 (13%) rare CNVs that impact potentially clinically relevant developmental genes were found, suggesting that patients with suspected fetal alcohol syndrome should be evaluated for genetic imbalances. A similar suggestion is made by Jamuar et. al. (2018) after evaluation of 36 cases.

* This information is courtesy of the L M D.
If you find a mistake or would like to contribute additional information, please email us at: [email protected]

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