Question

1. What are Branchiootic and branchiootorenal syndromes? What are some of the

morphological abnormalities associated with the disease? Which genes are mutated in these

conditions? What is the role of these genes in placode development?

Answer 1

Branchiootic (branchio=2nd branchial arch+otic=ear) means this is a defect involving branchial arch (2nd branchial arch anamoly) and ear.

Branchiooticrenal means this disorder affects branchial arch ear along with kidney.

These are autosomal dominant genetic syndromes.

●Branchiootorenal syndrome is characterised by 》preauricular ear tags and pits,

》branchial fistula,branchial cyst,

》malformations of outer middle and inner ear

》renal abnormalities

● Branchiootic syndrome has ear and hearing abnormalities but kidney is spared.

Morphological abnormalities are

1.preauricular cartilagenous tags

2.cup shaped or small outer ear pinna

3.Narrow or upward slanted ear canal

4.abnormal shaped kidney or duplicate or absence of one kidney

5.Branchial cyat or. fistula

6.cleft palate (rare)

●For diagnosis of branchiootic and branchiooticrenal syndrome :

at least two of five features should be present
1.branchial defects,
2.hearing loss,
3. preauricular pits
4., abnormalities of the part of the ear that projects from the head (pinna),
5. renal malformations)

in an individual with two or more affected family members,
or three features are present in an individual with no affected family members.

●Genes mutated

mutations in the
EYA1(BOR1, BOS2),
SIX5 (BOR2), and
SIX1 (BOR3, BOS3) genes.

These genes are located on short arm of chromosome 14.

●Role of genes in placode formation

six1 () gene is involved in normal development of kidney