ORAI1 inhibition as an efficient preclinical therapy for tubular aggregate myopathy and Stormorken syndrome

Tubular aggregate myopathy (TAM) and Stormorken syndrome (STRMK) are clinically overlapping disorders characterized by childhood-onset muscle weakness and a variable occurrence of multisystemic signs, including short stature, thrombocytopenia, and hyposplenism. TAM/STRMK is caused by gain-of-function mutations in the Ca2+ sensor STIM1 or the Ca2+ channel ORAI1, both of which regulate Ca2+ homeostasis through the ubiquitous store-operated Ca2+ entry (SOCE) mechanism. Functional experiments in cells have demonstrated that the TAM/STRMK mutations induce SOCE overactivation, resulting in excessive influx of extracellular Ca2+. There is currently no treatment for TAM/STRMK, but SOCE is amenable to manipulation. Here, we crossed Stim1R304W/+ mice harboring the most common TAM/STRMK mutation with Orai1R93W/+ mice carrying an ORAI1 mutation partially obstructing Ca2+ influx. Compared with Stim1R304W/+ littermates, Stim1R304W/+Orai1R93W/+ offspring showed a normalization of bone architecture, spleen histology, and muscle morphology; an increase of thrombocytes; and improved muscle contraction and relaxation kinetics. Accordingly, comparative RNA-Seq detected more than 1,200 dysregulated genes in Stim1R304W/+ muscle and revealed a major restoration of gene expression in Stim1R304W/+Orai1R93W/+ mice. Altogether, we provide physiological, morphological, functional, and molecular data highlighting the therapeutic potential of ORAI1 inhibition to rescue the multisystemic TAM/STRMK signs, and we identified myostatin as a promising biomarker for TAM/STRMK in humans and mice.

Case Report: Novel STIM1 Gain-of-Function Mutation in a Patient With TAM/STRMK and Immunological Involvement

Gain-of-function (GOF) mutations in STIM1 are responsible for tubular aggregate myopathy and Stormorken syndrome (TAM/STRMK), a clinically overlapping multisystemic disease characterised by muscle weakness, miosis, thrombocytopaenia, hyposplenism, ichthyosis, dyslexia, and short stature. Several mutations have been reported as responsible for the disease. Herein, we describe a patient with TAM/STRMK due to a novel L303P STIM1 mutation, who not only presented clinical manifestations characteristic of TAM/STRMK but also manifested immunological involvement with respiratory infections since childhood, with chronic cough and chronic bronchiectasis. Despite the seemingly normal main immunological parameters, immune cells revealed GOF in calcium signalling compared with healthy donors. The calcium flux dysregulation in the immune cells could be responsible for our patient’s immune involvement. The patient’s mother carried the mutation but did not exhibit TAM/STRMK, manifesting an incomplete penetrance of the mutation. More cases and evidence are necessary to clarify the dual role of STIM1 in immune system dysregulation and myopathy.

Interhelical interactions within the STIM1 CC1 domain modulate CRAC channel activation

The calcium release activated calcium channel is activated by the endoplasmic reticulum-resident calcium sensor protein STIM1. On activation, STIM1 C terminus changes from an inactive, tight to an active, extended conformation. A coiled-coil clamp involving the CC1 and CC3 domains is essential in controlling STIM1 activation, with CC1 as the key entity. The nuclear magnetic resonance-derived solution structure of the CC1 domain represents a three-helix bundle stabilized by interhelical contacts, which are absent in the Stormorken disease-related STIM1 R304W mutant. Two interhelical sites between the CC1α1 and CC1α2 helices are key in controlling STIM1 activation, affecting the balance between tight and extended conformations. Nuclear magnetic resonance-directed mutations within these interhelical interactions restore the physiological, store-dependent activation behavior of the gain-of-function STIM1 R304W mutant. This study reveals the functional impact of interhelical interactions within the CC1 domain for modifying the CC1-CC3 clamp strength to control the activation of STIM1.

CRAC channels and disease - From human CRAC channelopathies and animal models to novel drugs

Ca²⁺ release-activated Ca²⁺ (CRAC) channels are intimately linked with health and disease. The gene encoding the CRAC channel, ORAI1, was discovered in part by genetic analysis of patients with abolished CRAC channel function. And patients with autosomal recessive loss-of-function (LOF) mutations in ORAI1 and its activator stromal interaction molecule 1 (STIM1) that abolish CRAC channel function and store-operated Ca²⁺ entry (SOCE) define essential functions of CRAC channels in health and disease. Conversely, gain-of-function (GOF) mutations in ORAI1 and STIM1 are associated with tubular aggregate myopathy (TAM) and Stormorken syndrome due to constitutive CRAC channel activation. In addition, genetically engineered animal models of ORAI and STIM function have provided important insights into the physiological and pathophysiological roles of CRAC channels in cell types and organs beyond those affected in human patients. The picture emerging from this body of work shows CRAC channels as important regulators of cell function in many tissues, and as potential drug targets for the treatment of autoimmune and inflammatory disorders.

Mutagenesis of Snu114 domain IV identifies a developmental role in meiotic splicing

Snu114, a component of the U5 snRNP, plays a key role in activation of the spliceosome. It controls the action of Brr2, an RNA-stimulated ATPase/RNA helicase that disrupts U4/U6 snRNA base-pairing prior to formation of the spliceosome's catalytic centre. Snu114 has a highly conserved domain structure that resembles that of the GTPase EF-2/EF-G in the ribosome. It has been suggested that the regulatory function of Snu114 in activation of the spliceosome is mediated by its C-terminal region, however, there has been only limited characterisation of the interactions of the C-terminal domains. We show a direct interaction between protein phosphatase PP1 and Snu114 domain 'IVa' and identify sequence 'YGVQYK' as a PP1 binding motif. Interestingly, this motif is also required for Cwc21 binding. We provide evidence for mutually exclusive interaction of Cwc21 and PP1 with Snu114 and show that the affinity of Cwc21 and PP1 for Snu114 is influenced by the different nucleotide-bound states of Snu114. Moreover, we identify a novel mutation in domain IVa that, while not affecting vegetative growth of yeast cells, causes a defect in splicing transcripts of the meiotic genes, SPO22, AMA1 and MER2, thereby inhibiting an early stage of meiosis.

A Genomic Region Containing REC8 and RNF212B Is Associated with Individual Recombination Rate Variation in a Wild Population of Red Deer (Cervus elaphus)

Recombination is a fundamental feature of sexual reproduction, ensuring proper disjunction, preventing mutation accumulation and generating new allelic combinations upon which selection can act. However it is also mutagenic, and breaks up favorable allelic combinations previously built up by selection. Identifying the genetic drivers of recombination rate variation is a key step in understanding the causes and consequences of this variation, how loci associated with recombination are evolving and how they affect the potential of a population to respond to selection. However, to date, few studies have examined the genetic architecture of recombination rate variation in natural populations. Here, we use pedigree data from ∼ 2,600 individuals genotyped at ∼ 38,000 SNPs to investigate the genetic architecture of individual autosomal recombination rate in a wild population of red deer (Cervus elaphus). Female red deer exhibited a higher mean and phenotypic variance in autosomal crossover counts (ACC). Animal models fitting genomic relatedness matrices showed that ACC was heritable in females ([Formula: see text] = 0.12) but not in males. A regional heritability mapping approach showed that almost all heritable variation in female ACC was explained by a genomic region on deer linkage group 12 containing the candidate loci REC8 and RNF212B, with an additional region on linkage group 32 containing TOP2B approaching genome-wide significance. The REC8/RNF212B region and its paralogue RNF212 have been associated with recombination in cattle, mice, humans and sheep. Our findings suggest that mammalian recombination rates have a relatively conserved genetic architecture in both domesticated and wild systems, and provide a foundation for understanding the association between recombination loci and individual fitness within this population.

New Role for an Old Protein: An Educational Primer for Use with "The Identification of a Novel Mutant Allele of topoisomerase II in Caenorhabditis elegans Reveals a Unique Role in Chromosome Segregation During Spermatogenesis"

Modern experimental techniques, such as whole-genome sequencing and clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 endogenous genome editing, are enabling researchers to identify and further characterize the roles of proteins that were previously thought of as well defined. In the December 2016 issue of GENETICS, an article by Jaramillo-Lambert et al. identified a new role for the enzyme topoisomerase II in Caenorhabditis elegans male meiosis. This Primer article is designed to provide essential background information on C. elegans spermatogenesis and the relevant scientific techniques that will assist students and instructors in their understanding and discussion of the related article.Related article in GENETICS: Jaramillo-Lambert, A., A. S. Fabritius A. S., T. J. Hansen T. J., H. E. Smith H. E., and A. Golden A., 2016 The identification of a novel mutant allele of topoisomerase II in Caenorhabditis elegans reveals a unique role in chromosome segregation during spermatogenesis. Genetics204: 1407-1422.

Divergent Development of Hexaploid Triticale by a Wheat - Rye -Psathyrostachys huashanica Trigeneric Hybrid Method

Hexaploid triticale is an important forage crop and a promising energy plant. Some forms were previously reported for developing the hexaploid triticale, such as crossing tetraploid wheat or hexaploid wheat with rye, crossing hexaploid triticale and/or hexaploid wheat with octoploid triticale, and spontaneously appearing in the selfed progenies of octoploid triticale. In the present study, we developed an effective method for production of diverse types of hexaploid triticale via wheat—rye—Psathyrostachys huashanica trigeneric hybrid. Genomic in situ hybridization (GISH) and fluorescence in situ hybridization (FISH) karyotyping revealed that D genome chromosomes were completely eliminated and the whole A, B, and R genome chromosomes were retained in three lines. More interestingly, the composite genome of the line K14-489-2 consisted of complete A and B genomes and chromosomes 1D, 2R, 3R, 4R, 5R, 6R, and 7R, that of line K14-491-2 was 12 A-genome (1A-6A), 14 B-genome (1B-7B), 12 R-genome (1R-3R, 5R-7R), and chromosomes 1D and 3D, and that of the line K14-547-1 had 26A/B and 14R chromosomes, plus one pair of centric 6BL/2DS translocations. This finding implies that some of D genome chromosomes can be spontaneously and stably incorporated into the hexaploid triticale. Additionally, a variety of high-molecular-weight glutenin subunits (HMW-GS) compositions were detected in the six hexaploid triticale lines, respectively. Besides, compared with its recurrent triticale parent Zhongsi828, these lines showed high level of resistance to stripe rust (Puccinia striiformis f. sp. tritici, Pst) pathogens prevalent in China, including V26/Gui 22. These new hexaploid triticales not only enhanced diversification of triticale but also could be utilized as valuable germplasm for wheat improvement.

York platelet syndrome is a CRAC channelopathy due to gain-of-function mutations in STIM1

Store-operated Ca(2+) entry is the major route of replenishment of intracellular Ca(2+) in animal cells in response to the depletion of Ca(2+) stores in the endoplasmic reticulum. It is primarily mediated by the Ca(2+)-selective release-activated Ca(2+) (CRAC) channel, which consists of the pore-forming subunits ORAI1-3 and the Ca(2+) sensors, STIM1 and STIM2. Recessive loss-of-function mutations in STIM1 or ORAI1 result in immune deficiency and nonprogressive myopathy. Heterozygous gain-of-function mutations in STIM1 cause non-syndromic myopathies as well as syndromic forms of miosis and myopathy with tubular aggregates and Stormorken syndrome; some of these syndromic forms are associated with thrombocytopenia. Increased concentration of Ca(2+) as a result of store-operated Ca(2+) entry is essential for platelet activation. The York Platelet syndrome (YPS) is characterized by thrombocytopenia, striking ultrastructural platelet abnormalities including giant electron-opaque organelles and massive, multilayered target bodies and deficiency of platelet Ca(2+) storage in delta granules. We present clinical and molecular findings in 7 YPS patients from 4 families, demonstrating that YPS patients have a chronic myopathy associated with rimmed vacuoles and heterozygous gain-of-function STIM1 mutations. These findings expand the phenotypic spectrum of STIM1-related human disorders and define the molecular basis of YPS.

The Rim15-endosulfine-PP2ACdc55 signalling module regulates entry into gametogenesis and quiescence via distinct mechanisms in budding yeast

Quiescence and gametogenesis represent two distinct survival strategies in response to nutrient starvation in budding yeast. Precisely how environmental signals are sensed by yeast cells to trigger quiescence and gametogenesis is not fully understood. A conserved signalling module consisting of Greatwall kinase, Endosulfine and Protein Phosphatase PP2A^Cdc55 proteins regulates entry into mitosis in Xenopus egg extracts and meiotic maturation in flies. We report here that an analogous signalling module consisting of the serine-threonine kinase Rim15, the Endosulfines Igo1 and Igo2 and the Protein Phosphatase PP2A^Cdc55, regulates entry into both quiescence and gametogenesis in budding yeast. PP2A^Cdc55 inhibits entry into gametogenesis and quiescence. Rim15 promotes entry into gametogenesis and quiescence by converting Igo1 into an inhibitor of PP2A^Cdc55 by phosphorylating at a conserved serine residue. Moreover, we show that the Rim15-Endosulfine-PP2A^Cdc55 pathway regulates entry into quiescence and gametogenesis by distinct mechanisms. In addition, we show that Igo1 and Igo2 are required for pre-meiotic autophagy but the lack of pre-meiotic autophagy is insufficient to explain the sporulation defect of igo1Δ igo2Δ cells. We propose that the Rim15-Endosulfine-PP2A^Cdc55 signalling module triggers entry into quiescence and gametogenesis by regulating dephosphorylation of distinct substrates.

The fundamental property of a cell is to sense changes in the environment and then respond in a way that maximizes its chances of survival. When diploid budding yeast cells are subjected to complete nutrient starvation they have two possible fates, namely quiescence and gametogenesis. Quiescent cells have reduced rates of transcription and translation and increased stress tolerance. Gametogenesis results in production of haploid spores that can survive for long periods of time. In this paper, we report a signalling module that regulates entry into both quiescence and gametogenesis in budding yeast. The module consists of three molecular components namely a serine-threonine kinase Rim15, a phosphatase PP2A^Cdc55 and a conserved protein called as endosulfine. PP2A^Cdc55 negatively regulates entry into gametogenesis and quiescence. Upon nutrient starvation, Rim15 becomes active and phosphorylates endosulfine. This converts endosulfine to an inhibitor of PP2A^Cdc55 and thereby leading to entry into quiescence and gametogenesis. Remarkably, an analogous module consisting of Greatwall kinase, PP2A-B55δ and endosulfine regulates entry into mitosis in frog egg extracts and meiotic maturation in flies suggesting that this signalling module is highly conserved and co-opted during evolution to control distinct biological processes in different organisms.

Genetic variants in REC8, RNF212, and PRDM9 influence male recombination in cattle

We use >250,000 cross-over events identified in >10,000 bovine sperm cells to perform an extensive characterization of meiotic recombination in male cattle. We map Quantitative Trait Loci (QTL) influencing genome-wide recombination rate, genome-wide hotspot usage, and locus-specific recombination rate. We fine-map three QTL and present strong evidence that genetic variants in REC8 and RNF212 influence genome-wide recombination rate, while genetic variants in PRDM9 influence genome-wide hotspot usage.

Homologous recombination is an essential cellular process that determines proper chromosome segregation during meiosis, affects fertility, and influences evolvability. Nevertheless, the components of the recombination apparatus remain incompletely characterized in mammals. One approach to identify such components is to identify the genes that underlie inherited variation in recombination phenotypes. In addition to providing mechanistic insights, this would allow the study of the evolutionary forces that shape the recombination process. In this paper, we take advantage of genotypes for 50,000 genome-wide SNP markers to measure four recombination phenotypes (genome-wide recombination rate, genome-wide hotspot usage, locus-specific recombination rate, genome-wide cross-over interference) for >750 bulls on the basis of >250,000 cross-overs detected in sperm cells transmitted to >10,000 sons. We quantify the heritability and scan the genome for Quantitative Trait Loci (QTL) influencing each one of these recombination phenotypes. We perform a detailed genetic analysis of three such QTL, thereby providing evidence that genetic variants in REC8 and RNF212 influence genome-wide recombination rate, while genetic variants in an X-linked PRDM9 paralogue influence genome-wide hotspot usage.

Chromatin configuration and epigenetic landscape at the sex chromosome bivalent during equine spermatogenesis

Pairing of the sex chromosomes during mammalian meiosis is characterized by the formation of a unique heterochromatin structure at the XY body. The mechanisms underlying the formation of this nuclear domain are reportedly highly conserved from marsupials to mammals. In this study, we demonstrate that in contrast to all eutherian species studied to date, partial synapsis of the heterologous sex chromosomes during pachytene stage in the horse is not associated with the formation of a typical macrochromatin domain at the XY body. While phosphorylated histone H2AX (γH2AX) and macroH2A1.2 are present as a diffuse signal over the entire macrochromatin domain in mouse pachytene spermatocytes, γH2AX, macroH2A1.2, and the cohesin subunit SMC3 are preferentially enriched at meiotic sex chromosome cores in equine spermatocytes. Moreover, although several histone modifications associated with this nuclear domain in the mouse such as H3K4me2 and ubH2A are conspicuously absent in the equine XY body, prominent RNA polymerase II foci persist at the sex chromosomes. Thus, the localization of key marker proteins and histone modifications associated with the XY body in the horse differs significantly from all other mammalian systems described. These results demonstrate that the epigenetic landscape and heterochromatinization of the equine XY body might be regulated by alternative mechanisms and that some features of XY body formation may be evolutionary divergent in the domestic horse. We propose equine spermatogenesis as a unique model system for the study of the regulatory networks leading to the epigenetic control of gene expression during XY body formation.

Early onset autosomal dominant spinocerebellar ataxia with miosis: four cases

Previously, at least 29 different forms of autosomal dominant spinocerebellar ataxias (SCAs) have been described. We describe a family with four members through three generations with autosomal dominant ataxia in combination with miosis and hyperreflexia. This family's ataxia does not match any of the previously described SCAs and is probably a novel form of SCA. To continue with the search for the genetic background of this disease, more cases are needed.

Genetic homogeneity for inherited congenital microcoria loci in an Asian Indian pedigree

PURPOSE

Congenital microcoria is a rare autosomal dominant developmental disorder of the iris associated with myopia and juvenile open angle glaucoma. Linkage to the chromosomal locus 13q31-q32 has previously been reported in a large French family. In the current study, a three generation Asian Indian family with 15 congenital microcoria (pupils with a diameter <2 mm) affected members was studied for linkage to candidate microsatellite markers at the 13q31-q32 locus.

METHODS

Twenty-four members of the family were clinically examined and genomic DNA was extracted. Microsatellite markers at 13q31-q32 were PCR amplified and run on an ABI Prism 310 genetic analyzer and genotyped with the GeneScan analysis. Two point and multipoint linkage analyses were performed using the MLINK and SUPERLINK programs.

RESULTS

Peak two point LOD scores of 3.5, 4.7, and 5.3 were found co-incident with consecutive markers D13S154, DCT, and D13S1280. Multipoint analysis revealed a 4 cM region encompassing D13S1300 to D13S1280 where the LOD remains just over 6.0 Thus we confirm localization of the congenital microcoria locus to chromosomal locus 13q31-q32. In addition, eight individuals who had both microcoria and glaucoma were screened for glaucoma genes: myocilin (MYOC), optineurin (OPTN) and CYP1B1. Using direct sequencing a point mutation (144 G>A) resulting in a Q48H substitution in exon 1 of the MYOC gene was observed in five of the eight glaucoma patients, but not in unaffected family members and 100 unrelated controls.

CONCLUSIONS

We have confirmed the localization of the congenital microcoria locus (MCOR) to 13q31-q32 in a large Asian Indian family and conclude that current information suggests this is a single locus disorder and genetically homogeneous. When combined with the initial linkage paper our haplotype and linkage data map the MCOR locus to a 6-7 cM region between D13S265 and D13S1280. The DCT locus, a member of the tyrosinase family involved in pigmentation, maps within this region. Data presented here supports the hypothesis that congenital microcoria is a potential risk factor for glaucoma, although this observation is complicated by the partial segregation of MYOC Q48H (1q24.3-q25.2), a mutation known to be associated with glaucoma in India. Fine mapping and candidate gene analysis continues with the hope that characterizing the micocoria gene will lead to a better understanding of microcoria and glaucoma causation. The relationship between microcoria, glaucoma, and the MYOC Q48H mutation in this family is discussed.

Familial myopathy with tubular aggregates associated with abnormal pupils

The authors describe familial tubular aggregate myopathy associated with abnormal pupils. Four family members from two generations had myopathy and pupillary abnormalities. The myopathologic findings consisted of tubular aggregates in many fibers but predominantly type I fibers.

Hidden function of neuronal nicotinic acetylcholine receptor β2 subunits in ganglionic transmission: comparison to α5 and β4 subunits

Neuronal nicotinic acetylcholine receptors (nAChR), which modulate fast excitatory postsynaptic potentials (f-EPSP), are located on both pre- and postganglionic sites in the autonomic nervous system (ANS). The receptor subunits alpha3, alpha5, alpha7, beta2 and beta4 are present in autonomic ganglia in various combinations and modulate acetylcholine (ACh) transmission. In the present study, autonomic functions were systemically examined in mice lacking beta2 subunits (beta2-/-) to further understand the functional role of beta2 subunits in modulating ganglionic transmission. The results show normal autonomic functions, both under physiological conditions and in perturbed conditions, on thermoregulation, pupillary size, heart rate responses and ileal contractile reactions. This suggests that the function of beta2-containing receptors in ganglionic transmission is hidden by the predominant beta4 containing receptors and confirms previous studies which suggest that alpha3alpha5beta4 nAChRs are sufficient for autonomic transmission. On the other hand, beta2-containing receptors have only a minor function on postsynaptic responses to ACh, but may modulate ACh release presynaptically, although there is no evidence for this.

[Stormorken's syndrome]

In 1985, a new syndrome with the following characteristics was described: thrombopathia, thrombopenia, asplenia, miosis, headache, ichthyosis, dyslexia, muscle defect, and subsequently also hypocalcaemia. Skin and deep bleedings, leg spasms, disturbed dark vision and dyslexia are main worries. This paper describes these patients with a review of the investigations performed. Causes of the bleeding tendency are complex disturbances of the platelet membrane causing insufficient stability of the haemostatic plug, the nature of which is unresolved, but involves membrane scrambling. The muscle defect consists in tubular aggregates and high blood values of creatine kinase. A connection with the hypocalcaemia is possible, because increasing the ionic Ca with calcitriol significantly improves muscle function. Miosis is resistant to mydriatics and causes decreased dark vision, possibly also influencing dyslexia. The asplenia has little influence on immunocompetence, and the patients have survived 300 patient years without critical infections. The gene defect has not yet been unravelled.

[Muscle involvement of Stormorken's syndrome]

We described two patients, a mother and daughter, of Stormorken's syndrome. The syndrome is characterized clinically by autosomal dominant inheritance, congenital miosis, thrombocytopenia, asplenia and muscle weakness. Both patients had bleeding tendency, ichthyosis of arms, and muscle weakness. The daughter additionally had short stature (146 cm), low body weight (32 kg) and muscle cramp. Neurological findings of the patients included migraine-like headache, cognitive dysfunction, limitation of upward and lateral gaze, and amydriasis. Femoral muscle MRI of the daughter demonstrated decreased volume with patchy high intensity areas in the hamstrings. A muscle biopsy from the daughter showed myogenic changes with muscle fiber necrosis and regeneration, variation in fiber size, tubular aggregates in approximately 5% of fibers, and fibrous tissue proliferation. Dystrophin, dystrophin-associated proteins and dysferlin were normally expressed. Although both patients had elevated creatine kinase levels and generalized muscle wasting, muscle weakness was mild with slow progression. A certain membrane defect in the platelet and muscle fiber might be responsible for the pathogenesis of this syndrome.

A new hereditary syndrome with a bleeding tendency, extreme miosis, spasms, dyslexia, thrombocytopathia etc. Pupillometric, evaporimetric, and ophthalmological observations

A recently described familiar syndrome consists of the following components: A bleeding tendency with thrombocytopathia, miosis, muscular weakness and spasms, ichthyosis, asplenia, dyslexia, and headache. Four definite and 2 probable patients have been identified in 4 generations. In the present study, the pupillary behaviour was scrutinized in two 'definite' cases with the infrared, binocular pupillometer. The forehead sweating pattern was also investigated with an Evaporimeter. The basal pupillary widths were: 1.25-1.75 mm. Only minor responses were noted upon topical stimulation with an indirectly acting pupillodilating agent (OH-amphetamine). A directly acting sympathicomimetic drug (phenylephrine) exerted a more marked influence on the pupil, indicating a relative supersensitivity. The evaporimetric pattern in the forehead seemed to be within reference limits, at variance with what is the case in Horner's syndrome. Further findings were: the orbit seemed to be smaller than normal; a bilateral VI. cranial nerve palsy was identified, and a marked upward gaze palsy coexisted with pupils with Argyll Robertson's traits. There is no readily acceptable explanation for the ocular abnormalities. The disorder underlying the pupillary abnormality may possibly be located in the upper mesencephalon.

Autosomal dominant congenital miosis with megalocornea

A family with AD congenital miosis is presented. The ocular symptoms were: megalocornea, iris translucency, microcoria with poor pupillary dilatation and goniodysgenesis with anterior insertion of the iris. This observation confirms that in congenital miosis abnormal development of the whole anterior eye segment may occur. The patients have an increased risk to develop glaucoma. If retinoscopy is impossible due to pin-point pupils, ultrasonic biometry to determine the axial length is recommended. An optical iridectomy could improve visual performance at low illumination; the complaints of photophobia, which are related to the iris translucency, persist.