SLC7A7, encoding a putative permease-related protein, is mutated in patients with lysinuric protein intolerance.

Lysinuric protein intolerance (LPI, MIM 222700) is an autosomal recessive multisystem disorder found mainly in Finland and Italy. On a normal diet, LPI patients present poor feeding, vomiting, diarrhoea, episodes of hyperammoniaemic coma and failure to thrive. Hepatosplenomegaly, osteoporosis and a life-threatening pulmonary involvement (alveolar proteinosis) are also seen. LPI is caused by defective cationic amino acid (CAA) transport at the basolateral membrane of epithelial cells in kidney and intestine. Metabolic derangement is characterized by increased renal excretion of CAA, reduced CAA absorption from intestine and orotic aciduria. The gene causing LPI was assigned using linkage analysis to chromosome 14q11.2 near the T-cell receptor alpha/delta chains locus, and a critical region has been defined. We have identified two new transcripts (SLC7A8 and SLC7A7) homologous to amino acid transporters, highly expressed in kidney and mapping in the LPI critical region. Mutational analysis of both transcripts revealed that SLC7A7 (for solute carrier family 7, member 7) is mutated in LPI. In five Italian patients, we found either an insertion or deletion in the coding sequence, which provides evidence of a causative role of SLC7A7 in LPI. Furthermore, we detected a splice acceptor change resulting in a frameshift and premature translation termination in four unrelated Finnish patients. This mutation may represent the founder LPI allele in Finland.

Mowat-Wilson syndrome: facial phenotype changing with age: study of 19 Italian patients and review of the literature.

Mowat-Wilson syndrome (MWS; OMIM #235730) is a genetic condition caused by heterozygous mutations or deletions of the ZEB2 gene, and characterized by typical face, moderate-to-severe mental retardation, epilepsy, Hirschsprung disease, and multiple congenital anomalies, including genital anomalies (particularly hypospadias in males), congenital heart defects, agenesis of the corpus callosum, and eye defects. Since the first delineation by Mowat et al. [Mowat et al. (1998); J Med Genet 35:617-623], approximately 179 patients with ZEB2 mutations, deletions or cytogenetic abnormalities have been reported primarily from Europe, Australia and the United States. Genetic defects include chromosome 2q21-q23 microdeletions (or different chromosome rearrangements) in few patients, and ZEB2 mutations in most. We report on clinical and genetic data from 19 Italian patients, diagnosed within the last 5 years, including six previously published, and compare them with patients already reported. The main purpose of this review is to underline a highly consistent phenotype and to highlight the phenotypic evolution occurring with age, particularly of the facial characteristics. The prevalence of MWS is likely to be underestimated. Knowledge of the phenotypic spectrum of MWS and of its changing phenotype with age can improve the detection rate of this condition.

The molecular bases of cystinuria and lysinuric protein intolerance.

Cystinuria and lysinuric protein intolerance are inherited aminoacidurias caused by defective amino-acid transport activities linked to a family of heteromeric amino-acid transporters (HATs). HATs comprise two subunits: co-expression of subunits 4F2hc and y(+)LAT-1 induces the efflux of dibasic amino acids from cells, whereas co-expression of subunits rBAT and b(o,+)AT induces the renal reabsorption and intestinal absorption of cystine and dibasic amino acids at the brush border of epithelial cells. Recently, the role of b(o,+)AT (SLC7A9) in cystinuria (non Type I) and the role of y(+)LAT-1 (SLC7A7) in lysinuric protein intolerance have been demonstrated.

Holt-Oram syndrome associated with anomalies of the feet.

Holt-Oram syndrome (HOS) (OMIM 142900) is characterized by upper-extremity malformations involving the radial, thenar, or carpal bones and a personal and/or family history of congenital heart defects (CHDs). It is inherited in an autosomal dominant manner. The TBX5 gene located on chromosome 12 (12q24.1) is the only gene currently known to be associated with HOS and is associated with variable phenotypes. We report on the clinical and molecular characterization of a HOS family with three affected individuals and a novel mutation (Lys88ter). We discuss genotype-phenotype correlations, the presence of foot anomalies in one affected individual, and the role of atypical features in HOS differential diagnosis.

Incidence of ocular pathologies in Italian children with Down syndrome.

PURPOSE: This study identifies the incidence of primary ocular pathologies in a population of Italian children with Down syndrome. METHODS: A total of 157 Italian children with Down syndrome, age between 1 month and 18 years, were screened between February 2005 and October 2006. The ophthalmologic evaluation included a global inspection of orbit and bulbus oculi, evaluation of ocular motility and visual acuity, slit lamp biomicroscopy, cycloplegic skiascopy, tonometry, and indirect ophthalmoscopy. RESULTS: The overall incidence of ocular abnormalities was epicanthal fold (132 patients, 84%), hyperopia (93 patients, 59%), astigmatism (44 patients, 28%), myopia (14 patients, 9%), strabismus (56 patients, 36%, 45 cases of esotropia and 11 cases of exotropia), congenital nasolacrimal duct obstruction (35 patients, 22%), cataract (18 patients, 11%), nystagmus (9 patients, 6%), blepharitis and conjunctivitis (6 patients, 4%), and retinal anomalies (10 patients, 6%). Unlike previous reports in patients with Down syndrome, no congenital glaucoma, keratoconus, or Brushfield spots were observed. CONCLUSIONS: Compared to other studies in patients with Down syndrome, we observed a higher incidence of hyperopia and a lower incidence of myopia. The incidence of nystagmus, blepharitis,and conjunctivitis was less than that reported in other studies, while strabismus, especially exotropia (20%), had a high incidence in our cohort. We also frequently observed obstruction of the nasolacrimal duct (22%), but no keratoconus or glaucoma.

Characterization of phenylketonuria alleles in the Italian population.

In order to identify the molecular basis of phenylketonuria (PKU) in Italy, we screened the entire coding sequence of the phenylalanine hydroxylase gene in 20 Italian PKU patients, whose origins are scattered throughout Italy. The frequency of each identified mutation and of 5 other European mutations was determined within a panel of 92 Italian PKU patients. This approach allowed us to identify 20 different PKU mutations and characterize 64% of the Italian PKU chromosomes. Eleven mutations (IVS10nt546, L48S, R158Q, R261Q, P281L, R261X, R252W, delta T55, IVS7nt1, IVS12nt1, Y414C) represent 55.4% of the Italian PKU alleles, the most common mutations being IVS10nt546 (12.4%) and L48S (9%). All the other mutations are very rare. These data confirm the great heterogeneity expected from previous RFLP haplotype studies. Genotype/phenotype correlation allowed for assessment of the clinical impact of the 20 identified mutations.

Genetic homogeneity of lysinuric protein intolerance.

Lysinuric protein intolerance (LPI) is an autosomal recessive disorder in which transport of the cationic amino acids lysine, arginine and ornithine is defective at the basolateral membrane of the epithelial cells in the intestine and renal tubules. LPI is unusually common in Finland, but patients have been described on all continents. Linkage analysis in Finnish LPI families recently assigned the LPI gene locus to a 10 cM interval between markers D14S72 and MYH7 on the long arm of chromosome 14. In the present study linkage analysis of LPI families from six different non-Finnish populations strongly suggests genetic homogeneity in LPI. Peak lod scores were obtained at the chromosomal area between D14S72 and MYH7 with the same markers as in the Finnish families. The non-Finnish families showed no linkage disequilibrium except in an Italian family cluster, whereas strong allelic association in the Finnish families implies that LPI in Finland is caused by a founder mutation.

Smith-Lemli-Opitz syndrome: evidence of T93M as a common mutation of delta7-sterol reductase in Italy and report of three novel mutations.

The Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive disorder of cholesterol biosynthesis characterised by facial dysmorphisms, mental retardation and multiple congenital anomalies. SLOS is caused by mutations of the human Delta7-sterol reductase (DHCR7) gene and, so far, 19 different mutations have been described. Among these, mutations impairing the activity of the C-terminus appear to be the most severe. Here we report the mutational analysis of the DHCR7 gene in nine Italian SLOS patients. The T93M mutation, previously reported in one patient, results the most frequent one (7/18 alleles) in our survey. Furthermore, we identified three novel mutations, two missense mutations (N407Y and E448K), and a 33 bp deletion spanning part of exon 5 and the donor splice site of intron 5.

On the primary site of control in the spontaneous development of small-intestinal sucrase-isomaltase after birth.

We have compared the appearance in the small intestine of baby rabbits, of sucrase and isomaltase activities and of the sucrase-isomaltase mRNA. For the latter we used a cDNA probe encompassing approximately 4.1 kb from the 5'-end of pro-sucrase-isomaltase cDNA [(1986) Cell 46, 227-234]. Sucrase-isomaltase mRNA and the enzyme activities developed simultaneously from the 15th day after birth onwards. Over two orders of magnitude the enzymatic activities and sucrase-isomaltase mRNA matched one another closely, thus ruling out translation as the main site of biosynthetic control during spontaneous development, while rendering very probable transcription as the primary site of control. However, we cannot rule out the possibility that, prior to day 15, sucrase-isomaltase mRNA might be degraded so rapidly that it is not translated.

Contribution of the cystathionine beta-synthase gene (844ins68) polymorphism to the risk of early-onset venous and arterial occlusive disease and of fasting hyperhomocysteinemia.

The frequency of the heterozygous 844ins68 mutation of the cystathionine beta-synthase (CBS) gene and of its association with the homozygous C677T transition of the methylenetetrahydrofolate reductase (MTHFR) gene, plasma fasting tHcy, folate and vitamin B12 levels were evaluated in 309 consecutive patients with objectively diagnosed early-onset venous (n = 200) or arterial thromboembolic disease (n = 109) recruited over 25 months in Milan (North Italy) and Naples (South Italy). The above gene polymorphisms were also evaluated in a population of 787 unmatched controls, 204 of whom--similar to patients for age- and sex-distribution--had fasting tHcy, vitamins and activated protein C resistance measured in their plasma. Moderate fasting hyperhomocysteinemia was detected in 15.5% of patients and in 5.9% of 204 controls (Mantel-Haenszel OR after stratification for type of occlusive disease and gender: 2.88; 1.48-5.32). The frequencies of the 677TT mutation of the MTHFR gene and of the heterozygous 844ins68 insertion of the CBS gene were not significantly different in the patient (19.4% and 6.9%) and the control population (16.5% and 7.8%), but the association of the two gene polymorphisms found in 3.9% of patients and in 1.1% of controls - was significantly associated with an increased risk of venous or arterial occlusive diseases (RR = 3.63; 1.48-8.91). The MTHFR 677TT mutation (RR: 6.92; 3.86-12.4) and its association with the 844ins68 insertion (RR: 21.9; 8.35-57.4), but not the isolated insertion (RR: 0.71), were more frequent in patients and controls with fasting hyperhomocysteinemia than in normohomocysteinemic subjects, irrespective of the type of occlusive disease (venous or arterial). When adjusted for determinants of hyperhomocysteinemia in the patient and the control populations (generalized linear model), fasting tHcy levels were significantly higher in subjects with association of the two gene abnormalities (24.2+/-3.8 micromol/L) than in subjects with the MTHFR 677TT mutation only (14.0+/-5.8 micromol/L, p = 0.004). Activated protein C resistance was significantly more prevalent in venous patients (9.9%) than in controls (3.9%, OR = 2.69; 1.08-6.88). Six of 21 venous patients with APC-resistance also had hyperhomocysteinemia (RR = 5.04; 0.68-37.6), but isolated fasting hyperhomocysteinemia retained statistical significance for the association with venous occlusive disease (RR = 2.84; 1.34-6.01). Heterozygosity for the 844ins68 mutation of the CBS gene is not per se a risk factor for premature arterial and/or venous occlusive diseases. However, when detected in combination with thermolabile MTHFR, it increases by almost 4-fold the risk of occlusive diseases (arterial and/or venous), by increasing the risk and the degree of fasting hyperhomocysteinemia.

Congenital Alopecia and nail dystrophy associated with severe functional T-cell immunodeficiency in two sibs.

We report on two sisters affected by congenital alopecia, nail dystrophy, and a severe T-cell immunodeficiency, presumably inherited as an autosomal-recessive disorder. The T-cell defect was characterized by severe functional impairment, as shown by the lack of proliferative response and upregulation of activation markers following mitogen stimulation. The functional abnormality occurred in spite of the presence of phenotypically mature of the defect. This is the first observation reported on an ectodermal disorder, characterized by alopecia and nail dystrophy, observed at birth, in association with a primary immunodeficiency. The hypothesis that these two events may be casually related is discussed.

Geleophysic dysplasia: 7-year follow-up study of a patient with an intermediate form.

Geleophysic dysplasia (MIM *231050) is a rare autosomal recessive disorder, characterized by short stature with short limbs, brachydactyly, joint contractures, and a good-natured facial appearance. Infiltration of liver and cardiac leaflets has been reported in some patients. Based on the clinical picture and the detection of lysosome-like inclusions in hepatocytes, tracheal mucosa, chondrocytes, and skin fibroblasts, the underlying cause of the conditions is considered to be a generalized lysosomal storage defect. We report on a new case born to consanguineous parents, first observed at age 8 months, and for whom a 7-year follow-up is available.

Inv dup del (1)(pter-->q44::q44-->q42:) with the classical phenotype of trisomy 1q42-qter.

We report on a girl with a trisomy 1q42-q44 due to an inverted duplication of this region, associated with a terminal deletion of the long arm of the rearranged chromosome 1. Both the large duplication (more than 30 cM) and the small deletion were detected by FISH. Complete karyotype was: (46,XX, inv dup(1)(q44q42).ish(dup del 1)(q44q42)(D1S446x2, D1S423x2, tel1q-). The phenotype of the patient is characterized by macrocephaly with prominent forehead, downslanting palpebral fissures, micrognathia, and psychomotor retardation. All these clinical features are the same as observed for the typical trisomy 1q42-qter syndrome. The phenotypic effects of the inversion and the terminal deletion of 1q in addition to the trisomy are discussed here.

Fragile X founder chromosomes in Italy: a few initial events and possible explanation for their heterogeneity.

A total of 137 fragile X and 235 control chromosomes from various regions of Italy were haplotyped by analyzing two neighbouring marker microsatellites, FRAXAC1 and DXS548. The number of CGG repeats at the 5' end of the FMR1 gene was also assessed in 141 control chromosomes and correlated with their haplotypes. Significant linkage disequilibrium between some "major" haplotypes and fragile X was observed, while other "minor" haplotypes may have originated by subsequent mutation at the marker microsatellite loci and/or recombination between them. Recent evidence suggests that the initial mechanism leading to CGG instability might consist of rare (10 (-6/-7)) CGG repeat slippage events and/or loss of a stabilizing AGG via A-to-C transversion. Also, the apparently high variety of fragile X chromosomes may be partly due to the relatively high mutation rate (10 (-4/-5)) of the microsatellite markers used in haplotyping. Our fragile X sample also showed a higher than expected heterozygosity when compared to the control sample and we suggest that this might be explained by the chance occurrence of the few founding events on different chromosomes, irrespective of their actual frequency in the population. Alternatively, a local mechanism could enhance the microsatellite mutation rate only on fragile X chromosomes, or fragile X mutations might occur more frequently on certain background haplotypes.

Molecular and cytogenetic characterization of a recurrent unbalanced translocation (4;21)(p16.3;q22.1): relevance to the Wolf-Hirschhorn and Down syndrome critical regions.

We report on an aneuploidy syndrome due to the unbalanced segregation of a familial translocation (4;21)(p16.3;q22.1) causing a partial 4p monosomy and a partial 21q trisomy. The three affected children presented with severe failure to thrive, short stature, microcephaly, profound hypotonia, and mental retardation. The face, very similar in the three children, is characterized by frontal bossing, upslanting of the palpebral fissures, short nose, and deep set ears, giving the overall appearance of the Down syndrome. The molecular study has defined the aneuploid segment on both 4p and 21q. Most of the Down syndrome critical region was found to the trisomic, while only part of the candidate Wolf-Hirschhorn syndrome critical region was deleted, suggesting that this region is not critical for the major malformations characteristic for WHS.

Mosaicism for the full mutation and a microdeletion involving the CGG repeat and flanking sequences in the FMR1 gene in eight fragile X patients.

The molecular mechanism of the fragile X syndrome is based on the expansion of an unstable CGG repeat in the 5' untranslated region of the FMR1 gene in most patients. This expansion is associated with an abnormal DNA methylation leading to the absence of production of FMR1 protein (FMRP). Such expansion apparently predisposes the repeat and flanking regions to further instability that may lead to mosaic conditions with a full mutation and a premutation or, rarely, with normal or reduced alleles that can sometimes be transcriptionally active. In this study we describe eight unrelated fragile X patients who are mosaic for both a full mutation and an allele of normal (four cases) or reduced size (four cases). Sequencing analysis of the deletion breakpoints in 6 patients demonstrated an internal deletion confined to the CGG repeat in four of them, which represents the most likely explanation for the regression of the full mutation to a normal sized allele. In two patients with a reduced allele, the deletion encompassed the entire CGG repeat and part of the flanking regions. Analysis of FMRP by Western blot was performed in one of the mosaics with a normal sized allele and in three of those with a reduced allele. In the first patient's lymphocytes FMRP was detected, whereas in the three other patients the deletion is likely to impair transcription as no FMRP was present in their lymphocytes.

Case of Myhre syndrome with autism and peculiar skin histological findings.

Myhre syndrome (MS) (MIM 139210) is a rare disorder characterized by short stature, mental retardation, muscular build, blepharophimosis, and decreased joint mobility. We report on a 14-year-old boy with clinical findings consistent with a diagnosis of Myhre syndrome, associated with autism and peculiar skin histological findings.

[Efficacy of dietetic treatment in a case of galactosemia diagnosed late]. / Efficacia del trattamento dietetico in un caso di galattosemia tardivamente diagnosticata.

The authors describe a six months old girl affected by galactosemia, due to Galacto-1-phosphate Uridyl Transferase deficiency. The patient presented with hepatosplenomegaly and failure to thrive, without neurological impairment or cataracts. In this case removal of galactose from diet, although lately performed, resulted in normal growth and development. The authors emphasize the importance of ruling out galactosemia, even if clinical picture is unusual.

Regulation of alternative splicing in the IIICS region of human fibronectin pre-mRNA encoding cell binding sites CS1 and CS5.

The cell binding sites CS1 and CS5 in the IIICS region of human fibronectin (FN) mediate the adhesion of specific cell types by interacting with the integrin alpha 4 beta 1. IIICS pre-mRNA is alternatively spliced via the use of three alternative splice acceptor sites and one alternative splice donor site. These alternative splicing pathways can potentially give rise to variant FN molecules which are CS1+,CS5+; CS1+,CS5-; CS1-,CS5+ or CS1-,CS5-. Here we show that selection of the acceptor site which incorporates mRNA encoding CS1 and CS5 is more frequent in foetal tissues compared to adult liver, whereas an alternative acceptor site and the alternative donor site, which exclude CS1 and CS5, are used at a higher level in adult liver compared to foetal tissue. All possible splice junctions were accurately processed, and selected at different levels in mRNA expressed from a IIICS minigene transiently transfected into a HeLa cell line which does not express FN, suggesting that all the cellular factors required for alternative processing of IIICS are present in this system. Furthermore, pre-mRNA expressed from a mutant construct lacking IIICS-1 intron sequence, was correctly processed in HeLa cells via selection of all possible splice sites. On the basis of our results we propose that regulation of splice site selection in IIICS and thus expression of CS1 and CS5 is achieved by subtle tuning of splicing systems involving the interaction of local cis elements and cellular factors which are not necessarily restricted developmentally or tissue-specifically, and that expression of CS1 and CS5 is independently regulated.

A role for exon sequences in alternative splicing of the human fibronectin gene.

Exon EDIIIA of the fibronectin (Fn) gene is alternatively spliced via pathways which either skip or include the whole exon in the messenger RNA (mRNA). We have investigated the role of EDIIIA exon sequences in the human Fn gene in determining alternative splicing of this exon during transient expression of alpha globin/Fn minigene hybrids in HeLa cells. We demonstrate that a DNA sequence of 81bp within the central region of exon EDIIIA is required for alternative splicing during processing of the primary transcript to generate both EDIIIA+ and EDIIIA- mRNA's. Furthermore, alternative splicing of EDIIIA only occurs when this sequence is present in the correct orientation since when it is in antisense orientation splicing always occurs via exon-skipping generating EDIIIA- mRNA.