6-Pyruvoyl-tetrahydropterin synthase deficiency with generalized dystonia and diurnal fluctuation of symptoms: A clinical and molecular study page 1
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6-Pyruvoyl-tetrahydropterin synthase deficiency with generalized dystonia and diurnal fluctuation of symptoms: A clinical and molecular study

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  • Movement Disorders Vol. 12. No. 3, 1997, pp. 408-411 0 19Y7 Movement Disorder Society

    6-Pyruvoyl-Tetrahydropterin Synthase Deficiency with Generalized Dystonia and Diurnal Fluctuation of

    Symptoms: A Clinical and Molecular Study

    T. Hanihara, K. Inoue, C. Kawanishi, N. Sugiyama, T. Miyakawa, H. Onishi, Y. Yarnada, H. Osaka, K. Kosaka, ?K. Iwabuchi, and ZM. Owada

    Departmenti of Psychiatry and *Pediatrics, Yokohama City University of Medicine, Yokohama; TDepartment of Psychiatry, Kunagawa Rehabilitation Center, Atsugc; and $Department of Pediatrics, Nihon University, Tokyo, Jupun

    Summary: We report the case of a 44-year-old woman with a partial 6-pyruvoyl tetrahydropterin synthase (6-PTS) deficiency, whose predominant clinical symptom was gen- eralized dystonia with marked diurnal fluctuation. Dystonia was present in the eyelids, oromandibular region, trunk, and extremities (Meige syndrome plus double hemiplegia- like dystonia). A marked and sustained positive response to levodopa was observed. A molecular genetic study re- vealed a homozygous mutation (I114V) in the 6-PTS gene. This study indicates that genetic abnormality in the 6-PTS

    gene may be a hereditary dystonic disorder. We speculate that our patient has residual 6-PTS activity in the central nervous system, such as in the liver, and we suggest that residual, but insufficient production of tretrahydrobiopt- erin may play an important role in causing diurnal fluctua- tion of symptoms., Key Words: Tetrahydrobiopterin-6- Pyruvoyl tetrahyaropterin synthase deficiency-Orofacial dyskinesia-Dopa-responsive dystonia-Hereditary pro- gressive dystonia-Diurnal fluctuation.

    Tetrahydrobiopterin (BH4) is the natural cofactor of the aromatic acid oxidases: phenylalanine 4- hydroxylase, tyrosine 3-hydroxylase, and trypto- phan 5-hydroxylase. Any enzyme defect of BH4 bio- synthesis and regeneration results in a deficiency of amine transmitters, accompanied by hyperphenyla- laninemia. Three variants of the primary form of BH4 deficiency have been reported: GTP cyclohydrolase 1 (GTPCH1) deficiency, 6-pyruvoyl tetrahydropterin synthase (6-PTS) deficiency, and dihydropterin re- ductase deficiency. They are all inherited recessively (1). Patients with BH4 deficiency typically show se- vere neurological symptoms in infancy, including sei- zures, hypotonia, delayed motor development and mental retardation (2). 6-PTS catalyzes the second step in the biosynthesis of BH4, and 6-PTS deficiency

    Received February 19,1996, and in revised form June 10,1996. Accepted June 21, 1996.

    Address correspondence and reprint requests to Dr. T. Hanihara at Yokohama Comprehensive Care Continuum, 1735 Toriyama- cho, Kohoku, Yokohama, Kanagawa 222, Japan.

    is the most common variant of primary BH4 defi- ciency (1).

    Very few patients with 6-PTS deficiency with dys- tonia have been reported (3,4). Recently, it was estab- lished that hereditary progressive dystonia with marked diurnal fluctuation (HPD/Segawa) or dopa- responsive dystonia (DRD) is caused by heterozy- gous mutations in the gene encoding GTPCH1, which catalyzes the first step in the biosynthesis of BH4 (5 ) . In this article, we report the case of an adult patient with 6-PTS deficiency, with generalized dystonia and diurnal fluctuation of symptoms. We identified a ho- mozygous missense mutation in the 6-PTS gene of the patient. This study indicates that genetic abnor- mality in the 6-PTS gene may be manifested as a hereditary dystonic disorder clinically separate from classical DRD/HPD.

    CASE REPORT

    The patient was a 44-year-old woman, the firstborn of three female siblings from consanguineous par-

    408

  • PTS DEFICIENCY WITH DYSTONIA 409

    ents. The second sister had almost identical features as the patient; however, she died of acute cardiac failure at the age of 32. The patient was born at full term after an uncomplicated pregnancy and delivery, and her neonatal course was uneventful. She had a tonic-clonic seizure at 18 months. She experienced few subsequent seizures despite being untreated. At the time, her parents noticed that she crawled mostly with her arms, and her legs were often fixed in an extended posture. At the age of 2, she showed signs of spasticity in the lower extremities, and a diagnosis of cerebral palsy was made. She started to walk with an unsteady scissors gait at 4 years. Her speech and intellect were thought to be normal. Diurnal fluctua- tions of motor ability were noted at 7 years; she could walk in the morning without any assistance, but not in the evening. She went to elementary school only in the mornings. She was able to walk until the age of 27.

    At age 30, she was admitted to our institution. She was found to be mentally retarded (total IQ 60 on Wechslear Adult Intelligence Scale [WAIS]). Her routine laboratory examinations, cerebrospinal fluid (CSF) study, computed tomography brain scan, and EEG were normal. No further diagnosis was made. Physical rehabilitation programs improved her ability to move only slightly, and she became wheelchair- bound. At age 41, she was readmitted for reevalua- tion. On examination, bilateral pes equinovarus was noted. Tendon reflexes were hyperactive, and planter responses were flexor. In the mornings, dystonia was absent, and she could move in her wheelchair by herself. At midday, blepharospasms and oroman- dibular dyskinesia often appeared; blinking in- creased, and mouth opening and closing and bizarre tongue protrusion appeared. Simultaneously, her muscle tone gradually increased, and she demon- strated nuchal rigidity, flexion of the elbows and wrists, and extension of the knees and ankles. Coarse tremors often occurred in the fingers and upper limbs. By the end of the day, she was immobile with double hemiplegia-like posture. At that time she had great difficulty falling asleep. After a nap, the dystonia and involuntary movements disappeared completely.

    An amino acid analysis found her serum phenyl- alanine concentration to be mildly elevated (3.5- 5.6 mg/dl). Pterin compound analysis of the urine found a high urinary percentage of neopterin (Table 1). Homovanillic acid and 5-hydroxyindoleacetic acid (5-HIAA) levels in the cerebrospinal fluid were within normal range (27.6 ng/ml and 11.1 ng/ml. re- spectively). A diagnosis of partial (mild form) 6-PTS

    TABLE 1. Urinary pterin excretion

    Our patient Controls

    NP 61 26.3 2 9.6% BP + BH2 27 73.7 2 Y.6% BH4 12 19.2 ? 7.2%

    NP, neopterin; BP, biopterin; BH2, dihydrobioptcrin; BH4, tet- rahydrobiopterin.

    Taken from Tanaka et al. (3).

    deficiency was made. The patient was treated with levodopa (100 mg with 28.5 mg benserazide hydro- chloride per day), and she experienced a dramatic improvement within 24 h. The spontaneous dystonia completely disappeared. She could then move in her wheelchair by herself all day. The beneficial effects of levodopa have been sustained for 3 years.

    MOLECULAR STUDIES

    Reverse Transcription Polymerase Chain Reaction (RT-PCR) and Sequencing

    Total RNA was extracted from peripheral white blood cells of the patient. The 6-PTS cDNA was synthesized and amplified by RT-PCR. The amplified products were sequenced using an automatic se- quencing system (373A; Applied Biosystems, CA, U.S.A.) after subcloning into a vector, pCR-I1 (In- vitrogen, CA, U.S.A.). Sequencing identified an A- to-G missense mutation at the first position of codon 114, which indicated an amino acid change from iso- leucine to valine (Fig. 1).

    PCWRestriction Fragment Length Polymorphism (RFLP) Analysis of Exon 2 of 6-PTS Gene, Using

    Mismatch Primer

    Since this mutation does not make any cleavage site for restriction enzymes, we designed a set of

    Patient T T T A T G T C T G 114 Ile

    Wild type T T T A T A T C T G

    FIG. 1. Sequencing of 6-pyruvoyl-tetrahydrobiopterin synthase cDNA of the patient. An A-to-G transition is present in the first position in codon 114, which indicates an amino acid change from isoleucine to valine. Each primer sequence for RT-PCR was as follows: primer-A 5-CCAAGATGAGCACGGAAGG-3 and primer B 5-TTCAATAAATAGGCACTCCAGA-3.

    114 V a l

    Movement Disorders, Vol. 12, No. 3, 1997

  • 410 T. HANIHARA ET AL.

    primers for detection of this mutation (I114V). If the I114V mutation exists in the genomic DNA, the Eco R V site is diminished by PCR with a sense-primer mismatched at one nucleotide (the sense: 5'-TA-

    and antisense 5'-CGTACAACAATCACGTGTT- GACCTC-3') (6). We examined the patient, her mother, her healthy sister, and 50 unrelated controls. Total DNA was extracted from peripheral white blood cells. The second exon was amplified by PCR using the specific primers, and amplified PCR prod- ucts were incubated with EcoR V for 16 h.

    On RFLP analysis, a nondigested single band was present in the patient; both nondigested and 30-bp- shortened digested bands were present in the mother and the sister. PCR fragments of all 50 controls were digested as a 30-bp-shortened single band (data not shown). These results indicate that the patient has a homozygous mutation, and both her mother and healthy sister have heterozygous mutations; this mu- tation is specific to this family, rather than being a normal polymorphism.

    TAGCAOGACTGAAAATGTAGCTG'ITGAT - 3'

    DISCUSSION

    Patients with 6-PTS deficiencies typically develop neurological symptoms in infancy, such as motor de- velopmental delay, mental retardation, neonatal hy- potonia, and seizures, as a form of primary BH4 defi- ciency. These clinical presentations are thought to be related to depletion of neurotransmitters (1,2). Our patient had some of the clinical features of typical BH4 deficiency. Seizures were noted only in early childhood. Her mental retardation was mild. The clin- ical prog