Clinical Characteristics
Ocular Features
Tapetoretinal degeneration has been described in several patients. Some patients have keratoconus with lens and corneal opacities. Visual acuities have not been reported. The full ocular phenotype must be considered unknown since most patients have not had full ophthalmic evaluations.
Systemic Features
Features of an osteodysplasia are among the most striking in this syndrome. Short stature, brachydactyly, delayed bone age, osteoporosis, and hypoplasia of the acetabulae and iliac alae are usually present. Birth weight is often low. Joints may be hyperflexible as part of the generalized hypotonia. The eyes are deep-set, the nasal bridge is prominent, the midface is flat, and the supraorbital ridges are prominent giving the face a rather coarse look. Prognathism with a prominent lower lip and dental malocclusion reinforce this appearance. Seizures beginning in early childhood may be difficult to control. Most patients have severe psychomotor retardation and never acquire speech.
Genetics
Inheritance
The genetics of this familial disorder remain unknown. No locus or mutation has been identified but one patient had an absent maternal allele of the proximal 15q region as found in Angelman syndrome.
Orofaciodigital syndrome IX (258865) is another autosomal recessive syndrome sometimes called Gurrieri syndrome. In Gurrieri’s original description of two brothers, chorioretinal lacunae, similar to those seen in Aicardi syndrome (304050), were present. The systemic features are dissimilar, however.
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.