Familial advanced sleep phase syndrome (FASPS) is an autosomal dominant circadian rhythm variant; affected individuals are “morning larks” with a 4-hour advance of the sleep, temperature, and melatonin rhythms. Here we report localization of the FASPS gene near the telomere of chromosome 2q. A strong candidate gene (h Per2 ), a human homolog of the period gene in Drosophila , maps to the same locus. Affected individuals have a serine to glycine mutation within the casein kinase I ɛ (CKI ɛ ) binding region of hPER2, which causes hypophosphorylation by CKI ɛ in vitro. Thus, a variant in human sleep behavior can be attributed to a missense mutation in a clock component, hPER2, which alters the circadian period.

Andersen's syndrome is characterized by periodic paralysis, cardiac arrhythmias, and dysmorphic features. We have mapped an Andersen's locus to chromosome 17q23 near the inward rectifying potassium channel gene KCNJ2. A missense mutation in KCNJ2 (encoding D71V) was identified in the linked family. Eight additional mutations were identified in unrelated patients. Expression of two of these mutations in Xenopus oocytes revealed loss of function and a dominant negative effect in Kir2.1 current as assayed by voltage-clamp. We conclude that mutations in Kir2.1 cause Andersen's syndrome. These findings suggest that Kir2.1 plays an important role in developmental signaling in addition to its previously recognized function in controlling cell excitability in skeletal muscle and heart.

Familial advanced sleep phase syndrome (FASPS) is a human behavioural phenotype characterized by early sleep times and early-morning awakening. It was the first human, mendelian circadian rhythm variant to be well-characterized, and was shown to result from a mutation in a phosphorylation site within the casein kinase I (CKI)-binding domain of the human PER2 gene. To gain a deeper understanding of the mechanisms of circadian rhythm regulation in humans, we set out to identify mutations in human subjects leading to FASPS. We report here the identification of a missense mutation (T44A) in the human CKIdelta gene, which results in FASPS. This mutant kinase has decreased enzymatic activity in vitro. Transgenic Drosophila carrying the human CKIdelta-T44A gene showed a phenotype with lengthened circadian period. In contrast, transgenic mice carrying the same mutation have a shorter circadian period, a phenotype mimicking human FASPS. These results show that CKIdelta is a central component in the mammalian clock, and suggest that mammalian and fly clocks might have different regulatory mechanisms despite the highly conserved nature of their individual components.

Circadian rhythms are endogenous oscillations of physiological and behavioral phenomena with period length of approximately 24 hr. A mutation in human Period 2 (hPER2), a gene crucial for resetting the central clock in response to light, is associated with familial advanced sleep phase syndrome (FASPS), an autosomal dominant condition with early morning awakening and early sleep times. The FASPS hPER2 S662G mutation resulted in PER2 being hypophosphorylated by casein kinase I (CKI) in vitro. We generated transgenic mice carrying the FASPS hPER2 S662G mutation and faithfully recapitulate the human phenotype. We show that phosphorylation at S662 leads to increased PER2 transcription and suggest that phosphorylation at another site leads to PER2 degradation. Altering CKIdelta dosage modulates the S662 phenotype demonstrating that CKIdelta can regulate period through PER2 in vivo. Modeling a naturally occurring human variant in mice has yielded novel insights into PER2 regulation.

The diagnosis of idiopathic paroxysmal kinesigenic dyskinesia (PKD) can be made based on historical features. The correct diagnosis has implications for treatment and prognosis, and the diagnostic scheme may allow better focus in the search for the PKD gene(s).

Alternating hemiplegia of childhood (AHC) is a rare, severe neurodevelopmental syndrome characterized by recurrent hemiplegic episodes and distinct neurologic manifestations. AHC is usually a sporadic disorder with unknown etiology. Using exome sequencing of seven patients with AHC, and their unaffected parents, we identified de novo nonsynonymous mutations in ATP1A3 in all seven AHC patients. Subsequent sequence analysis of ATP1A3 in 98 additional patients revealed that 78% of AHC cases have a likely causal ATP1A3 mutation, including one inherited mutation in a familial case of AHC. Remarkably, six ATP1A3 mutations explain the majority of patients, including one observed in 36 patients. Unlike ATP1A3 mutations that cause rapid-onset-dystonia-parkinsonism, AHC-causing mutations revealed consistent reductions in ATPase activity without effects on protein expression. This work identifies de novo ATP1A3 mutations as the primary cause of AHC, and offers insight into disease pathophysiology by expanding the spectrum of phenotypes associated with mutations in this gene.

Adult-onset autosomal dominant leukodystrophy (ADLD) is a slowly progressive neurological disorder characterized by symmetrical widespread myelin loss in the central nervous system, with a phenotype similar to chronic progressive multiple sclerosis. In this study, we identify a genomic duplication that causes ADLD. Affected individuals carry an extra copy of the gene for the nuclear laminar protein lamin B1, resulting in increased gene dosage in brain tissue from individuals with ADLD. Increased expression of lamin B1 in Drosophila melanogaster resulted in a degenerative phenotype. In addition, an abnormal nuclear morphology was apparent when cultured cells overexpressed this protein. This is the first human disease attributable to mutations in the gene encoding lamin B1. Antibodies to lamin B are found in individuals with autoimmune diseases, and it is also an antigen recognized by a monoclonal antibody raised against plaques from brains of individuals with multiple sclerosis. This raises the possibility that lamin B may be a link to the autoimmune attack that occurs in multiple sclerosis.

ARTICLESBiological circadian clocks oscillate with an approximately 24-hour period, are ubiquitous, and presumably confer a selective advantage by anticipating the transitions between day and night. The circadian rhythms of sleep, melatonin secretion and body core temperature are thought to be generated by the suprachiasmatic nucleus of the hypothalamus, the anatomic locus of the mammalian circadian clock 1,2 . Autosomal semi-dominant mutations in rodents with fast or slow biological clocks (that is, short or long endogenous period lengths; τ) are associated with phase-advanced or delayed sleep-wake rhythms, respectively. These models predict the existence of familial human circadian rhythm variants 3,4 but none of the human circadian rhythm disorders are known to have a familial tendency 5 . Although a slight 'morning lark' tendency is common, individuals with a large and disabling sleep phase-advance are rare. This disorder, advanced sleep-phase syndrome, is characterized by very early sleep onset and offset; only two cases are reported in young adults 6,7 . Here we describe three kindreds with a profound phase advance of the sleep-wake, melatonin and temperature rhythms associated with a very short τ. The trait segregates as an autosomal dominant with high penetrance. These kindreds represent a well-characterized familial circadian rhythm variant in humans and provide a unique opportunity for genetic analysis of human circadian physiology.The first advanced sleep-phase syndrome (ASPS) patient in this study presented to our sleep center with disabling early evening sleepiness and early morning awakening. Because she recognized a similar trait in some family members, we evaluated consenting relatives from her extended family and from two additional families that were subsequently identified. A structured interview with each participant focused on the underlying preferred sleep schedule in the absence of psychosocial factors that would delay or advance sleep phase. Individuals were considered 'affected' if they described a life-long, stable pattern of early sleep onset and offset and met strict classification criteria. Individuals were considered 'unaffected' if they described an anambiguously normal or delayed sleep-wake schedule and 'unknown' if they did not meet either affected or unaffected criteria. We administered the Horne-Östberg questionnaire 8 (a validated measure of 'morning lark' or 'night owl' tendency).Using our strict classification criteria, we identified 29 people with familial ASPS (FASPS) and 46 unaffected people. ASPS segregates as a highly penetrant autosomal dominant trait in these families (Fig. 1). All three families are of Northern European descent (ancestors of kindreds 2174 and 3840 were from the British Isles). The youngest affected subject was 8 years old. Most FASPS subjects knew they were obligate 'morning larks' by 30 years of age. The Horne-Östberg scores were consistent with our classification scheme: FASPS patients, 76.2 ± 5.6 (n = 14); unaffected relatives, 60.5 ± 6.8 (n = 12) ...