Sex-linked Microphthalmia and Mental Deficiency

Some Genetical Problems in Mental Deficiency

The popular conception of mental defect is that it is a common abnormality of a kind fairly easy to understand and to study, and for whose ætiology simple rules can be laid down. Textbooks on general medicine usually dismiss the subject in a few paragraphs, and even those devoted to diseases of the mind rarely find room for more than one short chapter on mental defect.

Linkage analysis of Norrie disease with X-chromosomal ornithine aminotransferase

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Probably Norrie's disease due to mutation. Two sporadic sibships of two males each, a necropsy of one case, and, given Norrie's disease, a calculation of the gene mutation frequency

Two sibships, each with two affected males but no other affected family members, are described. All four patients at birth had small eyes with white masses visible behind clear lenses. Support for a diagnosis of Norrie's disease lies in the probable mental retardation and sudden death of one child and mental retardation in the other in one of the families, and strong support in the sensorineural deafness in one child in the other family. A necropsy was performed on the dead child. Both eyes showed the retinae to be totally non-attached. The optic nerves were thin. If the diagnosis is Norrie's disease (highly probable), the birth of the second affected child in each family supports the postulate of a mutation in the X chromosome of a germ cell of a maternal grandparent or an earlier maternal ancestor, no previous member of the family having been affected. That implies a 50% risk of the disease in future male siblings and a 50% risk of the carrier state in female sibs. When only one child is affected, the explanation could also be a mutation in that individual. Given Norrie's disease, we have calculated a mutation rate of 3.9 per million chromosomes in the Scottish population--remarkably similar to the mutation rates calculated for many dominant diseases. A diagnosis of autosomal recessive non-attachment of retina implies a 25% risk to later siblings.

Ocular findings in a new heritable syndrome of brain, eye, and urogenital abnormalities

We studied the clinical and histopathologic ocular findings in four related males with a newly recognized syndrome consisting of microphthalmos, microencephaly, mental retardation, agenesis of the corpus callosum, hypospadius, and cryptorchidism with X-linked recessive inheritance. The ocular abnormalities include microphthalmos, corneal pannus and hypoplasia, cataracts, uveal hypoplasia, retinal dysplasia, optic nerve hypoplasia, and congenital blepharoptosis. In case 4, a female twin who died in utero (at 15 weeks' gestation) showed none of the ocular abnormalities.

Anophthalmos in an infant with multiple congenital anomalies

A full-term, 2,828-g male infant who lived five weeks had histologically proven, bilateral, congenital anophthalmos. The infant had multiple congenital anomalies including esophageal atresia, choanal stenosis, tetralogy of Fallot, persistent left superior vena cava, arhinencephaly, retardation of myelination in the brain, cerebellar sclerosis, and dysplasias, as well as other developmental anomalies of the central nervous system. There was no family history of anophthalmos, and, in view of the arhinencephaly, we diagnosed sporadic secondary anophthalmos.