OMIM ID:
Microphthalmia, Syndromic 2
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
Microphthalmia with congenital cataracts are the outstanding ocular features of this syndrome. Some patients have glaucoma. Blepharophimosis, ptosis, and ankyloblepharon have also been reported.
Systemic Features
Facial dysmorphism, dental anomalies and cardiac defects are consistently present. The face may appear elongated while the nose can be short with a broad tip and long philtrum. The primary teeth often persist into the second decade but oligodontia, hyperdontia, and dental radiculomegaly may be seen as well. Reported cardiac defects include ASD, VSD and floppy valves. Some patients have cleft palate. Renal, and intestinal malformations have also been described and some patients exhibit psychomotor delays.
Genetics
Inheritance
This is an X-linked disorder secondary to a mutation in the BCOR gene at Xp11.4. Because virtually all patients are female, it has been suggested that this is an X-linked dominant mutation with lethality in hemizygous males (mother-daughter transmission has been reported). This is one of several disorders [others being Incontinentia pigmenti (308300)and focal dermal hypoplasia (305600)] in which skewed X-chromosome inactivation has been demonstrated.
Pedigree
X-linked dominant, father affected
X-linked inheritance patterns result when disease-causing mutations are located on the X chromosome. Males have one X chromosome while females have two. A mutation on the male's X chromosome frequently is lethal or renders him unable to reproduce. However, in rare cases when males have children, they can expect that all of then will inherit the condition.
X-linked inheritance patterns result when disease-causing mutations are located on the X chromosome. Males have one X chromosome while females have two. A mutation on the male's X chromosome frequently is lethal or at least renders them unable to reproduce. However, in rare cases when males have children, they can expect that all of then will inherit the condition.
X-linked dominant, mother affected
X-linked inheritance patterns result from mutations located on the X chromosome. Females have two X chromosomes of which only one carries a mutation in X-linked dominant disorders. This usually results in expression of the disease and women with a single mutation have the disorder caused by the mutation. Half of their offspring, male and female, will inherit the mutation. Men, with only one X chromosome, will always have the condition if they inherit the one with the mutation. Men would transmit it to all of their offspring. Without a modifying normal gene on a second X chromosome, X-linked dominant conditions are frequently lethal in such males. The result is a vertical transmission pattern, usually from female to female.
X-linked inheritance patterns result from mutations located on the X chromosome. Females have two X chromosomes of which only one carries a mutation in X-linked dominant disorders. This usually results in expression of the disease and women with a single mutation have the disorder caused by the mutation. Half of their offspring, male and female, will inherit the mutation. Men, with only one X chromosome, will always have the condition if they inherit the one with the mutation. Men would transmit it to all of their offspring. Without a modifying normal gene on a second X chromosome, X-linked dominant conditions are frequently lethal in such males. The result is a vertical transmission pattern, usually from female to female.