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Biomedical subjects

M Silengo

Publications and source records attributed to M Silengo.

At least 37 records · Page 2Linked to original sources
PubMed1999

Severe end of Opitz trigonocephaly (C) syndrome or new syndrome?

We report on four unrelated cases of an Opitz trigonocephaly (C)-like syndrome with a highly characteristic combination of facial anomalies including prominent metopic suture, exophthalmos, hypertelorism, cleft lip and palate, flexion deformities of the upper limbs and multiple other anomalies. We also review two very similar published cases formerly considered to have the C syndrome. Although there is overlap, a clinical distinction from the Opitz trigonocephaly and other syndromes seems possible, and thus a specific causal entity may be postulated.

Abnormalities, Multiple↗
PubMed1999

Different TBX5 interactions in heart and limb defined by Holt-Oram syndrome mutations.

To better understand the role of TBX5, a T-box containing transcription factor in forelimb and heart development, we have studied the clinical features of Holt-Oram syndrome caused by 10 different TBX5 mutations. Defects predicted to create null alleles caused substantial abnormalities both in limb and heart. In contrast, missense mutations produced distinct phenotypes: Gly80Arg caused significant cardiac malformations but only minor skeletal abnormalities; and Arg237Gln and Arg237Trp caused extensive upper limb malformations but less significant cardiac abnormalities. Amino acids altered by missense mutations were located on the three-dimensional structure of a related T-box transcription factor, Xbra, bound to DNA. Residue 80 is highly conserved within T-box sequences that interact with the major groove of target DNA; residue 237 is located in the T-box domain that selectively binds to the minor groove of DNA. These structural data, taken together with the predominant cardiac or skeletal phenotype produced by each missense mutation, suggest that organ-specific gene activation by TBX5 is predicated on biophysical interactions with different target DNA sequences.

Adult↗
PubMed1999

Lower extremity counterpart of the Poland syndrome.

Below-the-knee right leg hypoplasia and ipsilateral toe brachysyndactyly were observed in a 4-year-old female with an otherwise normal phenotype. Electromyographic and nerve conduction studies were normal. The Doppler evaluation was consistent with a 50% reduction in the blood supply from the femoral artery, suggesting vascular disruption as the pathogenic mechanism. Our observations support the hypothesis that a lower extremity counterpart of the Poland syndrome does exist and that the extent of limb involvement is dependent on the level of vascular disruption.

Child, Preschool↗
PubMed1999

Genetic mapping to 10q23.3-q24.2, in a large Italian pedigree, of a new syndrome showing bilateral cataracts, gastroesophageal reflux, and spastic paraparesis with amyotrophy.

We have recently observed a large pedigree with a new rare autosomal dominant spastic paraparesis. In three subsequent generations, 13 affected individuals presented with bilateral cataracts, gastroesophageal reflux with persistent vomiting, and spastic paraparesis with amyotrophy. Bilateral cataracts occurred in all affected individuals, with the exception of one patient who presented with a chorioretinal dystrophy, whereas clinical signs of spastic paraparesis showed a variable expressivity. Using a genomewide mapping approach, we mapped the disorder to the long arm of chromosome 10 on band q23.3-q24.2, in a 12-cM chromosomal region where additional neurologic disorders have been localized. The spectrum of phenotypic manifestations in this family is reminiscent of a smaller pedigree, reported recently, confirming the possibility of a new syndrome. Finally, the anticipation of symptoms suggests that an unstable trinucleotide repeat may be responsible for the condition.

Abnormalities, Multiple↗
PubMed1999

Identification of LMX1B gene point mutations in italian patients affected with Nail-Patella syndrome.

Nail-Patella syndrome, or osteo-onychodysplasia, is an autosomal dominant disorder characterized by nail dysplasia, absent or hypoplastic patellae, iliac horns and nephropathy. Previous studies have demonstrated linkage of the Nail-Patella locus with polymorphic markers on human chromosome 9q34. Recently, point mutations in the LMX1B gene have been identified in Nail-Patella patients and in families with recurrence of Nail-Patella syndrome and open-angle glaucoma. We describe here the identification of additional point mutations in the LMX1B gene in a set of Italian patients affected with Nail-Patella syndrome: two deletions of 1 and 2 bp causing a frameshift in two sporadic patients and nonsense mutations in two familial and one sporadic cases have been identified. All the mutations affect the homeodomain of the LMX1B protein and could cause the Nail-Patella syndrome through a loss of function as well as a dominant negative effect. Haplotype analysis in the two familial cases carrying the same stop codon mutation suggests the presence of a founder effect. Finally, analysis of cDNA clones obtained from human fetal kidney has revealed the existence of two different transcripts of LMX1B gene likely due to an alternative splicing.

Alternative Splicing↗
PubMed1998

Ectodermal dysplasia, primary hypothyroidism, and agenesis of the corpus callosum: variable expression of a single syndrome?

We present two unrelated children, a male and a female, with signs of ectodermal dysplasia, mental retardation, agenesis/ dysgenesis of the corpus callosum, and primary hypothyroidism. Reports of ectodermal dysplasia with CNS malformations or hypothyroidism or both are rare. We suggest that the condition we describe is a distinct entity within the large group of ectodermal dysplasia syndromes and that it has a variable clinical spectrum. As both males and females are affected and in a few reports some parents show minimal signs, the inheritance is likely to be autosomal dominant.

Agenesis of Corpus Callosum↗
PubMed1997

Trichorrhexis nodosa and lip pits in autosomal dominant ectodermal dysplasia--central nervous system malformation syndrome.

A Dandy-Walker-like malformation was observed in a retarded girl who had signs of hidrotic ectodermal dysplasia. This is the third report of the rare triad ectodermal dysplasia-CNS malformation-mental retardation. We observed additional findings, such as submucous cleft palate with lip pits and trichorrhexis nodosa. The proposita's mother had similar hair and facial changes. Two maternal relatives had cleft palate. Autosomal dominant inheritance is suggested.

Abnormalities, Multiple↗
PubMed1997

Frequency of RET mutations in long- and short-segment Hirschsprung disease.

Hirschsprung disease, or congenital aganglionic megacolon, is a genetic disorder of neural crest development affecting 1:5,000 newborns. Mutations in the RET proto-oncogene, repeatedly identified in the heterozygous state in both long- and short-segment Hirschsprung patients, lead to loss of both transforming and differentiating capacities of the activated RET through a dominant negative effect when expressed in appropriate cellular systems. The approach of single-strand conformational polymorphism analysis established for all the 20 exons of the RET proto-oncogene, and previously used to screen for point mutations in Hirschsprung patients allowed us to identify seven additional mutations among 39 sporadic and familial cases of Hirschsprung disease (detection rate 18%). This relatively low efficiency in detecting mutations of RET in Hirschsprung patients cannot be accounted by the hypothesis of genetic heterogeneity, which is not supported by the results of linkage analysis in the pedigrees analyzed so far. Almost 74% of the point mutations in our series, as well as in other patient series, were identified among long segment patients, who represented only 25% of our patient population. The finding of a C620R substitution in a patient affected with total colonic aganglionosis confirms the involvement of this mutation in the pathogenesis of different phenotypes (i.e., medullary thyroid carcinoma and Hirschsprung). Finally the R313Q mutation identified for the first time in homozygosity in a child born of consanguineous parents is associated with the most severe Hirschsprung phenotype (total colonic aganglionosis with small bowel involvement).

DNA Mutational Analysis↗
PubMed1995

RET mutations in exons 13 and 14 of FMTC patients.

RET is a receptor tyrosine kinase gene which is responsible for three different inherited cancer syndromes namely multiple endocrine neoplasia type 2A (MEN 2A), type 2B (MEN 2B) and familial medullary thyroid carcinoma (FMTC) as well as for Hirschsprung disease (HSCR), a congenital disorder affecting the intestinal motility. Germ-line mutations in the RET exons 10 and 11 were demonstrated in the majority of the MEN 2A and FMTC patients. On the other hand, one codon of RET exon 16 is preferentially changed in MEN 2B patients. Recently, a germ-line mutation in the exon 13 was described in one FMTC family as well as in four sporadic MTCs. In the present study, we observed the same exon 13 mutation in two FMTC families. In addition, we identified a previously unreported substitution of RET exon 14 in two unrelated FMTC families. Both mutations segregate with the disease in these four FMTC families and involve the tyrosine kinase domain of RET. Haplotype analysis using polymorphic markers tightly linked to the RET gene indicates that in each pedigree the mutation arose as an independent event.

Adult↗
PubMed1995

[Cardiofacial syndrome. A case report].

A case of cardio-facial syndrome with dysmorphic and asymmetric crying face, congenital heart defects, failure to thrive is described. The authors review the literature and underline the importance of asymmetric crying face as a marker of associated congenital anomalies.

Adolescent↗
PubMed1993

Uncombable hair, retinal pigmentary dystrophy, dental anomalies, and brachydactyly: report of a new patient with additional findings.

A new ectodermal dysplasia syndrome was reported by Bork et al. in 1987 (Hautarzt 38:342-347). The syndrome consisted of hypotrichosis with the typical SEM (scanning electron microscopy) changes of uncombable hair, retinal pigmentary dystrophy, juvenile cataract, oligodontia, brachydactyly with brachymetacarpia; it was inherited as an autosomal dominant trait. We describe a sporadic case and add further clinical findings to expand the spectrum of this rare syndrome.

Bone and Bones↗
PubMed1992

Monosomy 20 in childhood acute lymphoblastic leukemia.

We report two cases of acute lymphoblastic leukemia (ALL) with loss of chromosome 20 as the only karyotypic abnormality detected in the blast cells. The first patient is a 12-year-old boy studied at diagnosis. He represents the only case of monosomy 20 in our series of 90 pediatric ALL successfully karyotyped at diagnosis. In the second patient, monosomy 20 was detected at the second hematologic relapse, 12 years after the initial diagnosis; cytogenetic studies were not performed at disease onset.

Bone Marrow Cells↗
PubMed1992

Autosomal recessive microcephaly with early onset seizures and spasticity.

We describe two siblings, a male and a female pair, born of consanguineous parents, affected with a rare genetic form of congenital microcephaly. The clinical syndrome is characterized by early onset myoclonic seizures, spasticity, and profound psychomotor retardation without detectable brain malformations. To date, only two kindreds and one sporadic case with a similar clinical picture have been observed and reported (Tolmie et al. 1987, Bundey & Griffiths 1977). The severity of the neurological features and their perinatal onset differentiate the syndrome from the more common autosomal recessive microcephaly with spasticity/seizures.

Child, Preschool↗