We are having a report about different genetic disorders and i am task to explain edwards syndrome...
Trisomy 18(second most common autosomal trisomy) is a disorder that shows symptoms as soon as the child is born. About 25% of Edward's syndrome victims die before they are one month old, and only 10% live for one year.
The disorder is characterized by severe psychomotor and growth retardation, microcephaly, microphthalmia, malformed ears, micrognathia or retrognathia, microstomia, distinctively clenched fingers, and other congenital malformations.
Though there is no cure for trisomy 18, the symptoms of Edwards syndrome may be treated individually. For instance, since many children with trisomy 18 experience a growth deficiency, parents may want to speak with a nutritionist to help a child overcome this. Trisomic babies sometimes experience hearing loss, and hearing aids may be used to counter this.
If both parents have a genetic trait which is trisomy 18 when can it possibly be passed on?is it first filial or 2nd,third?how many percentage of the offsprings will manifest the trait?
In this disease actually the patient dies near about at age of 10 yrs , so there is no chance of progeny f1 f2 or f3
yeah but if take an hypothetical case then in the f1 gen. Of the case which u are refering to ,will show 50% normal and 50% trisomy
this diease is autosomal recessive.................................
This is from the OMIM database, you can find more information here: http://www.ncbi.nlm.nih.gov/omim as well as here: http://ghr.nlm.nih.gov/condition=oral-facial-digital-syndrome (Genetics Home Reference)
MIM ID %300484
OROFACIODIGITAL SYNDROME VIII; OFD8
Alternative titles; symbols
OFDS VIII
ORAL-FACIAL-DIGITAL SYNDROME, TYPE VIII
ORAL-FACIAL-DIGITAL SYNDROME WITH HYPOPLASTIC EPIGLOTTIS
EDWARDS SYNDROME
Clinical FeaturesBack to TopEdwards et al. (1988) described a family with orofaciodigital manifestations including hypertelorism or telecanthus, broad, bifid nasal tip, median cleft lip, tongue lobulation and/or hamartomas, oral frenula, high-arched or cleft palate, bilateral polydactyly, and duplicated halluces. Males in the family also had abnormal tibia, short stature, and recurrent aspiration pneumonia. The male proband also was noted to have almost complete hypoplasia of the epiglottis and arytenoid cartilages. X-linked recessive inheritance was suggested.
In a review of orofaciodigital syndromes, Toriello (1993) listed the male patient of Goodship et al. (1991), who had classified him as a case of OFDS type I (311200), as a probable case of OFDS VIII. The phenotype included hydrocephalus, absent corpus callosum, hypertelorism, pseudocleft upper lip, lobed tongue, oral frenula, cleft soft palate, atrioventricular septal defect, bifid halluces, and postaxial polydactyly of hands. Toriello (1993) stated that OFDS types I and VIII may be allelic, with male survival occurring in type VIII but not in type I.
We cannot say whether it is a recessive or dominant one , because it is not at all inherited from the (affected )parents....
and about the F1 generations they do not have any offsprings.
Trisomy 18 has no mode of inheritance like other diseases that are Autosomal Recessive/Autosomal Dominant/X-linked/Mitochondrial. Rather it is by nondisjunction (egg or sperm does not split its chromosomes completely) so you get THREE chromosome 18 instead of the usual TWO. You cannot make a pedigree for this.
{pseudo-trisomy 18 (Pena-Shokeir syndrome) is an autosomal recessive condition that can contain some overlap in the clinical features of that of trisomy 18}.
I know that there is no progency in this case
but i hav inquired frm some where that it is a recessive trait
i'll confirm again if u want
Thank you for the link Julie, I have placed a request on Johns Hopkins' OMIM databse asking them to review this.
Hi, if you are interested in additional info about trisomy 18, here's a nice link from genetic home reference:
http://ghr.nlm.nih.gov/condition/trisomy-18
Edwards syndrome is trisomy 18 where there is an extra chromosome at 18. Pure trisomy 18 occurs due to non disjunction. It is not autosomal recessive. The Risk of recurrence is less than 1percent. All cases of trisomy 18 will show some structural abnormalities that can be seen on prenatal ultrasound early in pregnancy .
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