OMIM ID:
Nystagmus 6, Congenital, X-linked
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
In several Chinese families, nystagmus was limited to males with onset in one case in the first 6 months. Foveal dysplasia was present along with mottled fundus pigmentation. Carrier females did not have nystagmus or changes in fundus pigmentation (except for one with mottling). Vision is in the range of 20/50-20/60.
Systemic Features
Skin and hair pigmentation was normal. No systemic disease was identified.
Genetics
Inheritance
Mutations in GPR143 (Xp22.2) have been identified in this form of nystagmus. The family pedigrees are consistent with X-linked recessive inheritance.
Two additional X-linked isolated nystagmus conditions are contained in this database: nystagmus 1 (310700), the result of mutations in FRMD7, and nystagmus 5 (300589) of unknown gene causation.
Several autosomal dominant forms have been linked to chromosomal regions 6p12 (NYS2; 164100), 7p11 (NYS3, 608345), 13q (NYS4, 193003), 1q31.3-q32.1, and NYS7 (614826). Autosomal recessive inheritance has been proposed for several pedigrees but adequate documentation is lacking (see 257400).
Ocular albinism (OA1) (300500) can also result from mutations in GPR143. However, there was no evidence of ocular or systemic hypopigmentation in the Chinese families.
Pedigree
X-linked recessive, father affected
X-linked disorders are caused by a mutation on the X chromosome and both sexes can pass this to their children. If the mutation is in a recessive gene and carried by the father, he has the disease since his only X chromosome is mutant and he has no normal X to blunt the effects of the abnormal gene. His sons only receive his Y chromosome and thus are all normal. However, all his daughters receive his one and only X chromosome and will be healthy 'carriers'. Thus such males will have no affected children but half their grandsons from those daughters will have the same disease as he does.
X-linked disorders are caused by a mutation on the X chromosome and both sexes can pass this to their children. If the mutation is in a recessive gene and carried by the father, he has the disease since his only X chromosome is mutant and he has no normal X to blunt the effects of the abnormal gene. His sons only receive his Y chromosome and thus are all normal. However, all his daughters receive his one and only X chromosome and will be healthy 'carriers'. Thus such males will have no affected children but half their grandsons from those daughters will have the same disease as he does.
X-linked recessive, carrier mother
X-linked disorders are caused by a mutation on the X chromosome and both sexes can pass this to their children. If the mutation is in a recessive gene and carried by the mother, she usually does not have the disease since the normal X chromosome without the mutation neutralizes the mutation in the abnormal X chromosome. However, half her sons will inherit the mutation-containing X chromosome and therefore have the X-linked disease. Half the daughters will inherit the mutation-bearing X chromosome and are usuallly healthy 'carriers'.
X-linked disorders are caused by a mutation on the X chromosome and both sexes can pass this to their children. If the mutation is in a recessive gene and carried by the mother, she usually does not have the disease since the normal X chromosome without the mutation neutralizes the mutation in the abnormal X chromosome. However, half her sons will inherit the mutation-containing X chromosome and therefore have the X-linked disease. Half the daughters will inherit the mutation-bearing X chromosome and are usuallly healthy 'carriers'.