Table 1

 Clinical features

FeatureAffected family member
The case numbers 1–5 correspond to the affected cases from left to right in fig 1 below.
Findings are graded by relative severity: −absent; +mild; ++moderate; +++severe.
IQ, Wechsler adult intelligence scale; LL, lower limb.
Age at examination (years)4239363022
Onset6 years6 years6 years6 years11 years
Tongue tremors+++++
Atrophy of small hand muscles+++++++++++++
Muscle toneSpastic LLSpastic LLSpastic LLSpastic LLSlightly spastic LL
Knee reflex++++++++++++
Extensor plantar response+++++++++
GaitSpastic ataxicSpasticSpasticSpasticSpastic
Emotional lability++++++++
IQTotal 55Total 61Total 54Total 56Total 68
Verbal 55Verbal 55Verbal 52Verbal 48Verbal 73
Performance 61Performance 72Performance 73Performance 73Performance 64