Introduction    
The ear is composed of three parts: the internal, middle and external portions. Microtia is a congenital anomaly, characterized by a narrow, blocked or absent ear canal. Microtia can affect one ear (unilateral) or both ears (bilateral). It occurs in every 1 out 6 000 to 12 000 births. The right ear is more commonly affected than left and it is more common in male sex as compared to female sex. On basis of anatomical involvement microtia may be classified in grades (Meurman, 1957).

Classification
Grade 1: A smaller version of a typical sized ear, still having same physical characteristic of a typical sized ear and containing a small but present external ear canal.

Grade 2: A partially formed outer ear with very small or narrow ear canal. The ear canal may be very narrow or closed (canal stenosis) producing a conductive hearing loss.

Grade 3: Absence of external ear with a small peanut shaped structure (some cartilage with mostly ear lobe) and an absence of the external ear canal and ear drum (known as aural atresia).

Grade 4: Absence of the complete ear (anotia).

In most instances the children with microtia disorders will have normal middle and inner ears, making a cosmetic condition rather than a typical cause of nerve deafness.

In this paper we discussed a case of microtia on one side and anotia on otherside.

Case report
A rare case of microtia was observed during OPD hours in Genetic Counseling Clinic at HAHC Hospital at Hamdard Institute of Medical Sciences and Research, Jamia Hamdard, New Delhi. A child was born with microtia (grade 3) on right side and a malformed external ear on the left side. On right side there was absence of external ear with small peanut shaped structure and absence of external ear canal (Figure 1). While on opposite side a large lobulated external ear was there with stenosis in ear canal (grade 2) see (Figure 2).
 

Figure 1 Picture showing child with microtia grade 3 on right side (arrow indicate)

Figure 2 Picture showing child with large lobulated left external ear with stenosis in ear canal (arrow indicating)

No one of either parents or their family members were having any congenital malformation or defects including face or ears specially. So a negative family history indicates role of some mutation or enviormental factor had played some role at time of intrauterine development in form of radiation/medication/pollutants. A recessive genetic trait may be blamed for this anomaly because partial consanguinity in marriage of parent was there. Child was assessed and found freefrom other congenital malformation as well as diseases.

Discussion
Cases of microtia may be difficult to define. Approximately 29% of the cases of diagnosed microtia do not have full atresia of the external auditory meatus (Castillo and Orioli, 1986). Anotia accounts for 13%~22% of the cases of microtia and anotia combined (Harris et al., 1996; Mastroiacovo et al., 1995). Anotia/microtia is an isolated condition in 65% of cases (Harris et al., 1996; Mastroiacovo et al., 1995; Castilla and Orioli, 1986), although several investigations reported isolated rates of less than 50% (Sánchez et al., 1997; Castilla and Lopez-Camelo, 1990). Over 80% of the cases of microtia or anotia are unilateral (Sánchez et al., 1997; Mastroiacovo et al., 1995). Of the unilateral cases of microtia or anotia, approximately 60% occur on the right side (Paulozzi and Lary, 1999; Sánchez et al., 1997; Harris et al., 1996; Mastroiacovo et al., 1995). Autosomal dominant inheritance of microtia or anotia has been reported in some families (Buyse, 1990).

By reviewing all studies mentioned above and other medical literatuire suggested that bilateral microtia/anotia is a rare phenomena and if it is bilateral it may be heredity in nature but our findings are quite different because we found bilateral microtia/anotia without any hereditical association. That finding raise a question is microtia really has genetic correlation? Role of mutation can not be ruledout.

Chromosomal abnormalities occur in 6%~16% of cases of microtia or anotia (Sánchez et al., 1997; Harris et al., 1996). Chromosomal abnormalities associated with microtia or anotia include trisomy 21, trisomy 18, trisomy 13, and the deletion complexes 18q-, 18p-, and 5p- (Harris et al., 1996; Carey, 1993; Buyse, 1990). Other birth defects associated with microtia/anotia include holoprosencephaly, facial clefts, cardiac defects, anophthalmia/microphthalmia, esophageal atresia, limb reduction deformities, renal anomalies, polydactyly, and vertebral anomalies (Wang et al., 2001; Harris et al., 1996; Mastroiacovo  et al., 1995).

References
Buyse M.E., ed., 1990, Ear, Microtia-Atresia, In: Birth Defects Encyclopedia, Blackwell Scientific Publications, Cambridge, Massachusetts, pp.591-592
 
Carey J.C., 1993, External ear, In: Stevenson R.E., Hall J.G., Goodman R.M., eds., Human Malformations and Related Anomalies, Oxford University Press, New York, pp.193-219
 
Castilla E.E., and Lopez-Camelo J.S, 1990, The surveillance of birth defects in South America. In: Advances in Mutagenesis Research, Springer-Verlag, New York, pp.191-210 http://dx.doi.org/10.1007/978-3-642-75599-6_7      
http://dx.doi.org/10.1007/978-3-642-75599-6_6 
 
Castilla E.E., and Orioli I.M., 1986, Prevalence rates of microtia in South America, Int. J. Epidemiol., 15(3): 364-368 http://dx.doi.org/10.1093/ije/15.3.364 
 
Harris J., Källén B., and Robert E., 1996, The epidemiology of anotia and microtia, J. Med. Genet., 33(10): 809-813 http://dx.doi.org/10.1136/jmg.33.10.809 
 
Mastroiacovo P., Corchia C., Botto L.D., Lanni R., Zampino G., and Fusco D., 1995, Epidemiology and genetics of microtia-anotia: A registry based study on over one million births, J. Med. Genet., 32(6): 453-457 http://dx.doi.org/10.1136/jmg.32.6.453 
 
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Sánchez O., Méndez J.R., Gómez E., and Guerra D., 1997, Clinico-epidemiologic study of microtia, Invest. Clin., 38(4): 203-217 PMid: 9527388 
 
Wang R.Y., Early D.L., Ruder R.O., and Graham J.M., 2001, Syndromic ear anomalies and renal ultrasounds, Pediatrics, 108(2): E32 http://dx.doi.org/10.1542/peds.108.2.e32 PMid: 11483842