Question: Which syndromes are associated with heterochromia iridum?

Context:
To our knowledge, this is the first reported case of Ascher's syndrome associated with iris coloboma, heterochromia iridum, and narrowing of horizontal palpebral fissure and decreased outer intercanthal distance secondary to lengthening of lateral canthal ligament.
 Sensorineural hearing loss (17/20, 85.0%) and heterochromia iridum (20/20, 100.0%) were the most commonly observed clinical features in Chinese WS2 patients. 
Waardenburg Syndrome (WS) is an autosomal-dominant disorder characterized by sensorineural hearing loss and pigmentary abnormalities of the eyes, hair, and skin. Microphthalmia-associated transcription factor (MITF) gene mutations account for about 15% of WS type II (WS2) cases. 
The association of congenital Horner's syndrome and hypochromia iridum without anhidrosis is highly suggestive of sympathetic pathway injury early in life. 
The Waardenburg syndrome (WS) consists of at least two distinct autosomal dominant hereditary disorders. WS Type I has been mapped to the distal part of chromosome 2q and the gene identified as PAX3. Other gene(s) are responsible for WS Type II. 
Sensorineural hearing loss (77%) and heterochromia iridum (47%) were the two most important diagnostic indicators for WS Type II. 
WAARDENBURG'S SYNDROME AND HETEROCHROMIA IRIDUM IN A DEAF SCHOOL POPULATION.
Waardenburg's syndrome consists of lateral displacement of the inner canthi of the eyes (dystopia canthorum), a broad nasal root and confluent eyebrows, heterochromia iridum, a white forelock and congenital deafness.
To our knowledge, this is the first reported case of Ascher's syndrome associated with iris coloboma, heterochromia iridum, and narrowing of horizontal palpebral fissure and decreased outer intercanthal distance secondary to lengthening of lateral canthal ligament.
Sensorineural hearing loss (77%) and heterochromia iridum (47%) were the two most important diagnostic indicators for WS Type II.
Sensorineural hearing loss (17/20, 85.0%) and heterochromia iridum (20/20, 100.0%) were the most commonly observed clinical features in Chinese WS2 patients.
We present the genetic analyses conducted on a three-generation family (14 individuals) with three members affected with isolated-Hirschsprung disease (HSCR) and one with HSCR and heterochromia iridum (syndromic-HSCR), a phenotype reminiscent of Waardenburg-Shah syndrome (WS4).
Heterochromia iridis and Horner's syndrome due to paravertebral neurilemmoma.
[Iris heterochromia in acquired Horner's syndrome].
BACKGROUND: Heterochromia iridis, asymmetry of iris pigmentation, has been well described with congenital Horner syndrome.
A case of heterochromia iridis and Horner's syndrome is reported in a 7-year old girl with paravertebral neurilemmoma.
We present the genetic analyses conducted on a three-generation family (14 individuals) with three members affected with isolated-Hirschsprung disease (HSCR) and one with HSCR and heterochromia iridum (syndromic-HSCR), a phenotype reminiscent of Waardenburg-Shah syndrome (WS4)
To our knowledge, this is the first reported case of Aschers syndrome associated with iris coloboma, heterochromia iridum, and narrowing of horizontal palpebral fissure and decreased outer intercanthal distance secondary to lengthening of lateral canthal ligament
WAARDENBURGS SYNDROME AND HETEROCHROMIA IRIDUM IN A DEAF SCHOOL POPULATION
Waardenburgs syndrome consists of lateral displacement of the inner canthi of the eyes (dystopia canthorum), a broad nasal root and confluent eyebrows, heterochromia iridum, a white forelock and congenital deafness
Sensorineural hearing loss (17/20, 85.0%) and heterochromia iridum (20/20, 100.0%) were the most commonly observed clinical features in Chinese WS2 patients
Sensorineural hearing loss (17/20, 85.0%) and heterochromia iridum (20/20, 100.0%) were the most commonly observed clinical features in Chinese WS2 patients. 
A dominantly inherited syndrome associated with hypopigmentation, heterochromia irides, colobomatous eyes and bilateral hearing loss has been ascertained in Fleckvieh cattle (German White Fleckvieh syndrome). 
Sensorineural hearing loss (77%) and heterochromia iridum (47%) were the two most important diagnostic indicators for WS Type II.
Sensorineural hearing loss (17/20, 85.0%) and heterochromia iridum (20/20, 100.0%) were the most commonly observed clinical features in Chinese WS2 patients.
WAARDENBURG'S SYNDROME AND HETEROCHROMIA IRIDUM IN A DEAF SCHOOL POPULATION.

Answer: The syndromes that are associated with heterochromia iridum are:
1) Ascher's syndrome
2) Waardenburg Syndrome type II (WS2)
3) Horner's syndrome.
Exact answer: Ascher's syndrome, Waardenburg Syndrome type II, WS2, WS Type II, Horner's syndrome