OMIM ID:
Smith-Lemli-Opitz Syndrome
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
A large number of ocular anomalies have been found in SLO syndrome but the most common is blepharoptosis of some degree. No consistent pattern of ocular abnormalities has been reported. Atrophy and hypoplasia of the optic nerve, strabismus, nystagmus, and cataracts may be present. Abnormally low concentrations of cholesterol and cholesterol precursors have been found in all ocular tissues studied.
Systemic Features
This is a syndrome of multiple congenital anomalies. Among these are dwarfism, micrognathia, hard palate anomalies, hypotonia, anomalies of the external genitalia, polysyndactyly, microcephaly, and mental retardation. It has been suggested that many individuals have a characteristic behavioral profile consisting of cognitive delays, hyperreactivity, irritability, language deficiency, and autism spectrum behaviors. Some individuals exhibit aspects of self destructive behavior. Tissue levels of cholesterol are low.
Genetics
Inheritance
Pedigree
Autosomal recessive
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.