Patient group | Selection criterion 1 | Number of patients identified | Selection criterion 2 | Number of patients identified | Number (%) of samples received |
---|---|---|---|---|---|
OUH; Oulu University Hospital. Computer search at OUH was first performed to identify patients with specific discharge diagnoses that had been filed according to Finnish version of the International Statistical Classification of Diseases and Related Health Problems. Specific selection criteria were then applied to select patients with definite diagnoses. *Patients with insulin dependent diabetes mellitus obtain needles, syringes, insulin pens, and glucose sticks free of charge from the public health care units, and the supplies used are recorded. These patients were identified from the records of 40 of the 42 local authority health care units. Discharge diagnoses at one of the two regional hospitals in the area and the diabetes register of the other also were reviewed. †Patients with any combination of diabetes mellitus, sensorineural hearing impairment or epilepsy in first or second degree maternal relatives were included. ‡Most adult patients with epilepsy make regular follow up visits to the outpatient clinic of the department of neurology at OUH at least once a year. During a one year period, a physician involved in the study checked the charts of the patients visiting the clinic every day. The diagnosis of epilepsy was confirmed on this occasion, and patients receiving regular antiepileptic medication were included. No distinction was made between the types or aetiologies of epilepsy. §The cost of hearing aids is refunded in full by the public health service, and aids are supplied in the region only by the department of otorhinolaryngology at OUH. The register of hearing aids supplied was reviewed and patients were ascertained on the basis of the following clinical criteria: symmetric sensorineural hearing impairment with undefined aetiology; hearing impairment >30 dB (pure tone average of frequencies 0.5, 1, 2, and 4 kHz); a difference between the ears <10 dB; and use of a hearing aid at age <45 years. ¶Duchenne muscular dystrophy and other myopathies with definite molecular genetic diagnosis were excluded. **Demyelinating diseases and ischaemic diseases were excluded. | |||||
Ataxia | Any ataxia, unknown aetiology | 79 | Idiopathic cerebellar ataxia, age ≥20 years at visit | 39 | 26 (67) |
Diabetes* | Insulin treatment started at age 20–45 years | 479 | Family history of mitochondrial phenotype† | 169 | 143 (85) |
Epilepsy‡ | Age ≥20 years at visit, response to family history questionnaire | 945 | Family history of mitochondrial phenotype† | 223 | 165 (74) |
Hearing loss§ | Sensorineural hearing impairment, hearing aid obtained at age ≤45 years, current age ≥20 years | 242 | Family history of mitochondrial phenotype† | 108 | 82 (76) |
Lipoma | Any lipoma | 621 | Axial or multiple lipomas, age ≥20 years at visit | 150 | 107 (71) |
Myopathy | Any myopathy with clinical and EMG verification, age ≥20 years at visit | 146 | Myopathy of unknown aetiology or any muscle dystrophy¶ | 41 | 32 (78) |
Neuropathy | Any electrophysiologically defined idiopathic neuropathy, age ≥20 years at visit | 138 | Familial neuropathy or family history of mitochondrial phenotype† | 31 | 21 (68) |
Ophthalmoplegia | Double vision or ptosis, any age | 799 | Definite ophthalmoplegia or symmetric ptosis, age ≥20 years at examination | 15 | 15 (100) |
Optic atrophy | Decrease in visual acuity or optic disc abnormality, any cause, any age | 1542 | Optic atrophy of unknown aetiology**, current age ≥20 years | 42 | 30 (71) |
Total | 4991 | Total | 818 | 621 (76) |