Table 2.

L1 Syndrome: Comparison of Phenotypes in Male Probands by Select Features

FeatureL1 Phenotype
HSASMASA syndrome,
incl SPG1		X-linked complicated
CC agenesis
Hydrocephalus w/or w/o stenosis
of aqueduct of Sylvius 		100%Variable dilation of
the 3rd ventricle		−
CC agenesis/hypogenesis +
(accompanies
hydrocephalus)		+ in some100%
Intellectual disability SevereMild to moderateMild to moderate
Delayed speech +++
Spasticity of legs ++Variable
Adducted thumbs 50%<50%<50%

CC = corpus callosum; HSAS = X-linked hydrocephalus with stenosis of aqueduct of Sylvius; MASA = mental retardation [intellectual disability], aphasia [delayed speech], spastic paraplegia [shuffling gait], adducted thumbs; SPG1 = X-linked complicated hereditary spastic paraplegia type 1

From: L1 Syndrome

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