Table 1 Comparing symptoms of Sanfilippo type A as described in the literature[1, 3, 4] with our patients

Pregnancy and delivery complications:

35 to 43 weeks, birth weight: 3534g, maternal hypertension, mild bleeding, normal delivery for majority of patients.

Normal pregnancy, birth weight: 3300g, delivery by caesarean section, maternal hypertension, pre-eclampsia and breech presentation.

Normal pregnancy, birth weight: 3000g, delivery by caesarean section, maternal hypertension, pre-eclampsia and breech presentation.

First signs and symptoms:

Normal development until one year, later on developmental and speech delay with behavioral problems.

Normal development until one year, later on motor and speech delay.

Normal development until 1.5 years, later on motor and speech delay.

Facial dysmorphisms.

Negative.

Negative.

Hepatomegaly.

Negative.

Negative.

Recurrent diarrhea.

Negative.

Negative.

Recurrent ear, nose and/or throat (ENT) infections.

Negative.

Negative.

Age of diagnosis:

Median age of 4 years (range 2 to 47 years).

12 years.

10 years.

Behavioral problems:

Before 10 years of age: restlessness, temper tantrum, crying fits, hyperactivity, destructive and compulsive behavior and complete loss of initiative in the majority of patients.

At age three to four years: restlessness.

At age three to four years: restlessness.

At age 10 to 11 years: complete loss of initiative with autistic-like behavior.

At age 10 to 11 years: complete loss of initiative with autistic-like behavior.

Sleeping problems:

Onset at a median age of 4 years (range 0 to 35 years) with difficulties of falling asleep and frequent nocturnal wakening.

No sleep disturbance.

No sleep disturbance.

Hearing problems:

Present in about 40% of patients.

Moderate to severe sensory bilateral hearing loss; abnormal auditory potentials (BAER).

Moderate to severe sensory bilateral hearing loss; abnormal auditory potentials (BAER).

Visual problems:

Formal visual testing not possible.

Formal visual testing not possible.

Formal visual testing not possible.

Fundoscopy:

Retinitis pigmentosa one-third of patients older than 21 years.

Normal.

Normal.

Epilepsy:

About 66% developed epilepsy at a median age of 11 years (range 1 to 43 years), but well controlled by medication.

Onset of epileptic seizure at the age of 11 years but well controlled by valproic acid.

None.

Age at death:

Median 18 years (range 6 to 59).

Current age 13 years.

Current age 11 years.

Joint contractures:

Present.

Present.

Present.

Scoliosis:

Present.

Present.

Present.

Kyphosis:

Present.

Present.

Present.

Pes cavus:

Not described.

Present.

Present.

Skin discoloration:

Not described.

Present.

Present.

Dysmorphic features:

Present.

Obvious at 10 to 11 years of age.

Obvious at 10 to 11 years of age.

Magnetic resonance imaging (MRI) findings:

Not reported.

Diffuse hypomyelination, thin corpus callosum and progressive cerebral atrophy.

Diffuse hypomyelination and thin corpus callosum.