OMIM ID:
Carpenter Syndrome
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
A variety of ocular anomalies have been reported in Carpenter syndrome with none being constant or characteristic. The inner canthi are often spaced widely apart and many have epicanthal folds and a flat nasal bridge. Other reported abnormalities are nystagmus, foveal hypoplasia, corneal malformations including microcornea, corneal opacity, and mild optic atrophy and features of pseudopapilledema.
Systemic Features
Premature synostosis involves numerous cranial sutures with the sagittal suture commonly involved causing acrocephaly (tower skull). Asymmetry of the skull and a ‘cloverleaf’ deformity are often present. The polydactyly is preaxial and some degree of syndactyly is common especially in the toes. The digits are often short and may be missing phalanges. Some patients are short in stature. Structural brain defects may be widespread including atrophy of the cortex and cerebellar vermis. Septal defects in the heart are found in about one-third of patients. The ears can be low-set and preauricular pits may be seen. Some but not all patients have obesity and a degree of mental retardation.
Genetics
Inheritance
This is an autosomal recessive syndrome caused by a mutation in the RAB23 gene (6p12.1-q12).
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.