A patient with Allan-Herndon-Dudley Syndrome can be suspected if certain clinical findings are identified.


Chromosome location: Xq13.2

Gene affected: MCT8, also known as SLC16A2 (soluble carrier family 16, member 2)


Inheritance: X-linked, with males affected and females carriers


Clinical criteria – the presence of >= 2 of the following:

(1) hypotonia or dystonia

(2) difficulty feeding noticed soon after birth, with risk of aspiration

(3) truncal hypotonia

(4) muscle hypoplasia or asthenic build

(5) poor head control (cervical hypotonia)

(6) paroxysmal dyskinesia

(7) spastic paraparesis with dystonic or athetioc movements

(8) dysarthria or no speech

(9) severe psychomotor retardation and cognitive impairment


Additional findings:

(1) poor weight gain

(2) limb rigidity with contractures

(3) brisk deep tendon reflexes (DTR)

(4) clonus

(5) seizures

(6) difficulty walking or sitting


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