A. Baxova

Mutations in ANTXR1 Cause GAPO Syndrome

The genetic cause of GAPO syndrome, a condition characterized by growth retardation, alopecia, pseudoanodontia, and progressive visual impairment, has not previously been identified. We studied four ethnically unrelated affected individuals and identified homozygous nonsense mutations (c.262C>T [p.Arg88*] and c.505C>T [p.Arg169*]) or splicing mutations (c.1435-12A>G [p.Gly479Phefs*119]) in ANTXR1, which encodes anthrax toxin receptor 1. The nonsense mutations predictably trigger nonsense-mediated mRNA decay, resulting in the loss of ANTXR1. The transcript with the splicing mutation theoretically encodes a truncated ANTXR1 containing a neopeptide composed of 118 unique amino acids in its C terminus. GAPO syndromes major phenotypic features, which include dental abnormalities and the accumulation of extracellular matrix, recapitulate those found in Antxr1-mutant mice and point toward an underlying defect in extracellular-matrix regulation. Thus, we propose that mutations affecting ANTXR1 function are responsible for this diseases characteristic generalized defect in extracellular-matrix homeostasis.

Mutations in PNPLA6 are linked to photoreceptor degeneration and various forms of childhood blindness

Blindness due to retinal degeneration affects millions of people worldwide, but many disease-causing mutations remain unknown. PNPLA6 encodes the patatin-like phospholipase domain containing protein 6, also known as neuropathy target esterase (NTE), which is the target of toxic organophosphates that induce human paralysis due to severe axonopathy of large neurons. Mutations in PNPLA6 also cause human spastic paraplegia characterized by motor neuron degeneration. Here we identify PNPLA6 mutations in childhood blindness in seven families with retinal degeneration, including Leber congenital amaurosis and Oliver McFarlane syndrome. PNPLA6 localizes mostly at the inner segment plasma membrane in photoreceptors and mutations in Drosophila PNPLA6 lead to photoreceptor cell death. We also report that lysophosphatidylcholine and lysophosphatidic acid levels are elevated in mutant Drosophila. These findings show a role for PNPLA6 in photoreceptor survival and identify phospholipid metabolism as a potential therapeutic target for some forms of blindness.

SHOX gene defects and selected dysmorphic signs in patients of idiopathic short stature and Léri–Weill dyschondrosteosis

The aim of the study was to analyze frequency of SHOX gene defects and selected dysmorphic signs in patients of both idiopathic short stature (ISS) and Léri-Weill dyschondrosteosis (LWD), all derived from the Czech population. Overall, 98 subjects were analyzed in the study. Inclusion criteria were the presence of short stature (-2.0 SD), in combination with at least one of the selected dysmorphic signs for the ISS+ group; and the presence of Madelung deformity, without positive karyotyping for the LWD+ group. Each proband was analyzed by use of P018 MLPA kit, which covers SHOX and its regulatory sequences. Additionally, mutational analysis was done of the coding portions of the SHOX. Both extent and breakpoint localizations in the deletions/duplications found were quite variable. Some PAR1 rearrangements were detected, without obvious phenotypic association. In the ISS+ group, MLPA analysis detected four PAR1 deletions associated with a SHOX gene defect, PAR1 duplication with an ambiguous effect, and two SHOX mutations (13.7%). In the LWD+ group, MLPA analysis detected nine deletions in PAR1 region, with a deleterious effect on SHOX, first reported case of isolated SHOX enhancer duplication, and SHOX mutation (68.8%). In both ISS+ and LWD+ groups were positivity associated with a disproportionately short stature; in the ISS+ group, in combination with muscular hypertrophy. It seems that small PAR1 rearrangements might be quite frequent in the population. Our study suggests disproportionateness, especially in combination with muscular hypertrophy, as relevant indicators of ISS to be the effect of SHOX defect.

Mutation analysis of the MECP2 gene in patients of Slavic origin with Rett syndrome: novel mutations and polymorphisms

AbstractRett syndrome (RTT), an X-linked dominant neurodevelopmental disorder in females, is caused mainly by de novo mutations in the methyl-CpG-binding protein 2 gene (MECP2). Here we report mutation analysis of the MECP2 gene in 87 patients with RTT from the Czech and Slovak Republics, and Ukraine. The patients, all girls, with classical RTT were investigated for mutations using bi-directional DNA sequencing and conformation sensitive gel electrophoresis analysis of the coding sequence and exon/intron boundaries of the MECP2 gene. Restriction fragment length polymorphism analysis was performed to confirm the mutations that cause the creation or abolition of the restriction site. Mutationnegative cases were subsequently examined by multiple ligation-dependent probe amplification (MLPA) to identify large deletions. Mutation screening revealed 31 different mutations in 68 patients and 12 nonpathogenic polymorphisms. Six mutations have not been previously published: two point mutations (323T>A, 904C>T), three deletions (189_190delGA, 816_832del17, 1069delAGC) and one deletion/inversion (1063_1236del174;1189_1231inv43). MLPA analysis revealed large deletions in two patients. The detection rate was 78.16%. Our results confirm the high frequency of MECP2 mutations in females with RTT and provide data concerning the mutation heterogeneity in the Slavic population.

Novel FBN1 gene mutation and maternal germinal mosaicism as the cause of neonatal form of Marfan syndrome

Marfan syndrome (MFS) is an autosomal dominant disorder caused by mutations in the fibrillin 1 gene (FBN1). Neonatal form of MFS is rare and is associated with severe phenotype and a poor prognosis. We report on a newborn girl with neonatal MFS who displayed cyanosis and dyspnea on the first day of life. The main clinical features included mitral and tricuspid valve insufficiency, aortic root dilatation, arachnodactyly, and loose skin. Despite the presence of severe and inoperable heart anomalies, the girl was quite stable on symptomatic treatment and lived up to the 7th month of age when she died due to cardiorespiratory failure. Molecular‐genetic studies revealed a novel intronic c.4211‐32_‐13del mutation in the FBN1 gene. Subsequent in vitro splicing analysis showed this mutation led to exon 35 skipping, presumably resulting in a deletion of 42 amino acids (p.Leu1405_Asp1446del). Interestingly, this mutation is localized outside the region of exons 24–32, whose mutation is responsible for the substantial majority of cases of neonatal MFS. Although the family history of MFS was negative, the subsequent molecular genetic examination documented a mosaicism of the same mutation in the maternal blood cells (10–25% of genomic DNA) and the detailed clinical examination showed unilateral lens ectopy.

Foramina parietalia permagna: report of nine cases in one family.

Nine members of a family with foramina parietalia permagna (FPP), inherited as an autosomal dominant trait are reported. Although usually benign, FPP may be associated with other malformations.

Severe limb abnormalities: Nievergelt or new syndrome?

Since the characteristic mesomelic limb abnormalities of the autosomal-dominant Nievergelt syndrome (NS) may be casually nonspecific, we are unsure whether our patient with these abnormalities but also with severe, symmetrical hand and foot anomalies has an unusual form of Nievergelt syndrome or a previously apparently undescribed syndrome. This infants condition could represent an autosomal-dominant new mutation, or an autosomal or X-linked recessive disorder.

Radiographic abnormalities in Laron dwarfism

Radiographic abnormalities in two children with Laron dwarfism are described. In addition to a characteristic bone age, which was retarded for the chronological age but advanced for the height of the patients, there were marked skull changes and minor skeletal abnormalities in the long bones and vertebrae. Such findings on a skeletal survey should lead the radiologist to suspect the disorder.

Post-mortem magnetic resonance imaging and its irreplaceable role in determining CNS malformation (hydranencephaly) – Case report

Post-mortem magnetic resonance appears to be a method supplementary to classic pathological-anatomical autopsy in determining foetal abnormalities. Frequently, it plays a key role, primarily where autopsy options are in some way limited (developed autolysis, dilatation of the ventricular system). This case report demonstrates that post-mortem magnetic resonance imaging can precisely determine the type of congenital malformation (hydranencephaly), by contrast to ultrasound, with which alobar holoprosencephaly has been described, often presenting a differential diagnosis problem. Pathological-anatomical autopsy was significantly limited due to this diagnosis and this methodology was incapable of unequivocally determining the type of malformation. We would like to demonstrate by this case report the necessity of performing post-mortem magnetic resonance imaging so that we may precisely determine the diagnosis as requested by the parents and also be able to answer the question posed by risks for future pregnancies.

Micromelic dwarfism-humerus, femur, tibia type. Report of a case

A 12.5-year-old girl with severe micromelic dwarfism and characteristic radiographic findings is reported. The most important phenotypic abnormality was dwarfism (stature<100 cm); the patient had a normal face and intelligence. The diagnostic radiographic findings were those of spondylo-epimetaphyseal dysplasia characterized by severe shortening of humerus, femur and tibia, hypoplastic but normal-shaped fibula, ulna and radius, uniform shortening of the short tubular bones and moderately severe platyspondyly. These radiographic changes were already present at birth, which should make it possible to recognize the disease in the newborn. We propose naming this disorder micromelic dwarfism-humerus, femur, tibia type.