ATN1

Clinical Characteristics

To date 8 individuals are reported with a diagnosis of CHEDDA, so we are still learning about the clinical spectrum of this condition.

One individual was born prematurely at 33 weeks and died at 2 months of age due to respiratory distress in the setting of severe multiple congenital anomalies; the age range of other affected individuals is 1 to 9 years.

Concerns arose at birth or within the first three months of life regarding significant hypotonia, feeding difficulties, seizures, congenital malformations and distinctive facial features and all affected individuals have severe to profound global developmental delay/ intellectual disability, truncal hypotonia, global motor disability and very limited verbal communication.

Five have epilepsy: for four of these, the epilepsy could be described as a neonatal or infantile onset developmental encephalopathy. Hearing and visual impairments and functional gastrointestinal disorders were common and frequently severe with four individuals requiring orogastric feeding or total parenteral nutrition. Growth parameters were within the normal range other than suboptimal weight gain in those with more significant feeding difficulties.

Congenital structural anomalies were common but variable between individuals: four individuals had cardiac malformations including atrial and ventricular septal defects and abnormalities of the aorta and superior vena cava, two individuals had palatal clefts, three individuals had congenital renal anomalies, including unilateral renal agenesis/hypoplasia and two had an anteriorly placed anus. Common neuroanatomical abnormalities evident on examination of available MRI in one centre include thinning of the corpus callosum with low hanging medial parietal lobule, polymicrogyria of the sylvian fissure, a steep clival angle, parenchymal atrophy and thinning or absence of the falx cerebri. Several individuals have cranio-skeletal abnormalities: in particular two individuals had stenosis of craniocervical junction.

Some similarities between individuals affected by CHEDDA are able to be discerned by medical professionals: particular features being sparsity of the lateral forehead hair and low-set posteriorly rotated ears. Characteristic hand and feet features were overlapping toes, camptodactyly, persistent fetal fingertip pads and abnormalities of the palmar creases.