Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two brothers (Nos. 1 and 3), with physical and mental retardation and many other clinical characteristics in common, were both trisomic for 12p(ter leads to 12.1) and monosomic for 21p. Their mother (No. 5), the maternal grandmother (No. 7), aunt (No. 8), and a first-cousin (No. 9) were balanced translocation carriers, 46 rep (12;21) (p12.1;p11). Another cousin (No. 10) had Down syndrome: he had two normal 21 chromosomes in addition to both translocation chromosomes. A sister (No. 2), who died at the age of 1 year without being karyotyped, had several phenotypical features in common with her brothers. Our two cases of trisomy 12p (ter leads to 12.1) were compared with eight cases of trisomy 12p described earlier, and the following common characteristics were found: severe mental and physical retardation; flat and round, broad face with prominent cheeks; flat and broad nasal bridge with short nose; anteverted nostrils and large philtrum; broad and prominent lower lip; low-set or slanting ears, poorly formed with folded helix, prominent antihelix and deep concha; short neck; short sternum; "spade"-shaped fingers, the fifth being short; bilateral genu valgum; bilateral pes planus and talus valgus; increased space between the first and second toes; generalized hypotonia; and certain dermatoglyphic characteristics. An elevated serum lactate dehydrogenase (LDH) was measured in four cases.
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PMID:Trisomy 12p syndrome. Evaluation of a family with a t(12;21) (p12.1;p11) translocation with unbalanced offspring. 14 83

Two unpublished cases with partial tandem duplication of 12p and one previously published case were studied by fluorescence in situ hybridization using 11 cosmid DNA probes from 12p. We propose that the smallest duplications of 12(p13.2pter) and 12(p13.1p13.33) produce the "trisomy 12p syndrome" which is characterized by heavy birth weight, macrocephaly, muscular hypotonia, short neck, flat face, high forehead, prominent cheeks, large philtrum, short nose with anteverted nostrils, and broad everted lower lip. From a review of the published cases we conclude that gross malformations are lacking in "pure" trisomy 12p, and mental retardation is severe in complete and moderate in partial trisomy 12p. Polydactyly and accessory nipples were found only with almost complete trisomy 12p. Abnormalities of hair growth may be related to a gene at 12p. The sub-band 12p11.21 may be critical for acrocallosal syndrome. Macrocephaly may be due to a metabolic disorder.
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PMID:Clinical and molecular cytogenetic observations in three cases of "trisomy 12p syndrome". 872 17

Epilepsy, together with mental retardation, represents a common manifestation of chromosomal aberrations. Specific electroencephalographic (EEG) and epileptic patterns have been described in several chromosomal disorders, such as Angelman's syndrome, Miller-Dieker syndrome, Wolf-Hirschhorn syndrome, and ring 20 syndrome. A peculiar electroclinical pattern has also been identified in trisomy 12p syndrome. We report three patients with a pericentric inversion of chromosome 12, with breakpoints localized to p11-q13 and affected by epilepsy or EEG anomalies. Two suffered from epilepsy, which, in the clinical course, was mainly characterized by complex partial seizures with a semiology related to the temporal lobe. In one patient, myoclonic absences, head drop, and massive jerky attacks were also present. In both patients, generalized 3 Hz bursts were registered, together with multifocal and focal paroxysmal activity, which were most prominent in the temporoparietal and temporal areas, respectively. In the other patient, who had no epilepsy, EEG showed bioccipital paroxysmal activity. In all patients, the clinical picture was characterized by the presence of moderate mental retardation and behavioral disorders. The incidence of epilepsy or EEG anomalies among patients with a pericentric inversion of chromosome 12 remains to be ascertained. However, the present study confirms that chromosome 12 anomalies can be associated with epilepsy. Although myoclonic absence-like episodes can occasionally be part of the epileptic phenotype, the electroclinical pattern in pericentric inversion of chromosome 12 seems to be more polymorphic when compared with that observed in trisomy 12p syndrome.
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PMID:Epilepsy and electroencephalographic findings in pericentric inversion of chromosome 12. 1560 70

Cases of tetrasomy 12p and trisomy 12p are known to be associated with specific phenotypic abnormalities well described in the literature. Here, we report on the unusual case of a partial tetrasomy 12p found in an affected patient and in a mosaic constellation in the patient's mother, who showed no phenotypic abnormality. The index patient was a 16-year-old boy with clinical features similar to the "trisomy 12p syndrome" including mental retardation, macrocephaly, a short nose with anteverted nostrils, and a broad protruding lower lip. G-banding analysis and fluorescence in situ hybridization (FISH) experiments using locus specific YAC DNA probes revealed a derivative chromosome 12 with a partial triplication of the short arm with an inverted copy, flanked by two direct copies. Chromosome analyses in parental lymphocytes showed a chromosomal mosaicism in the phenotypically normal mother, with 12% cells exhibiting the same partial tetrasomy 12p as detected in her son. The allelic pattern of short tandem repeats (STR) in the mother's blood DNA showed that a chimerism can be excluded with high probability. To our knowledge, this is the first report of intrachromosomal triplication on chromosome 12, as well as partial tetrasomy 12p mosaicism. Moreover, as a consequence of the chromosomal aberration in the son it can be concluded that a gonadal mosaicism is present in the mother.
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PMID:Intrachromosomal triplication 12p11.22-p12.3 and gonadal mosaicism of partial tetrasomy 12p. 1665 58

In recent years, subtelomeric rearrangements have been identified as a major cause of multiple congenital anomalies (MCA)/mental retardation (MR) syndromes. Currently, more than 2,500 individuals with MR have been tested and subtelomeric rearrangements were detected in about 6%. Therefore, subtelomeric FISH analysis is indicated as a second tier test after high-resolution G-banding analysis, in subjects with otherwise unexplained developmental delay/MR and/or MCA. We describe a female patient and her maternal aunt, both showing a distinct phenotype, associated with the same complex subtelomeric rearrangement. Subtelomeric FISH testing performed between 1 year 9 months and 20 years after the initial karyotype showed, in both patients, distal trisomy 12p and distal monosomy 10p as follows: 46,XX.ish der(10)t(10;12)(p15.3;p13.31). Parental subtelomeric FISH analysis showed the proposita's mother (sister of Patient 2) and grandmother (mother to Patient 2), to have a balanced 10p:12p translocation. Both girls showed a similar phenotype with pre/postnatal growth retardation, moderate-to-severe developmental delay/MR, very poor/absent speech, hypotonia, lax ligaments, and a distinct pattern of malformation. On examination there were blepharophimosis; bilateral ptosis/epicanthus; broad, depressed nasal bridge with a beaked nose; short philtrum; low-set, posteriorly rotated, overfolded ears; micrognathia; mild webbing of the neck; mild broadening of thumbs; puffy hands/feet; long hallux; and sacral/coccygeal dimples. A slow overall improvement was seen in both patients over time. To our knowledge, a complex subtle rearrangement as the one seen in our patients has not been reported thus far. Our patients show features of partial 10p deletion syndrome rather than those of partial duplication 12p, confirming the general rule that deletions are more phenotypically penetrant than duplications.
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PMID:Subtelomeric analysis detects a familial 10p;12p rearrangement in two relatives with a distinct syndrome. 1716 46

Trisomy of the short arm of chromosome 12 is a rare genetic disease characterised by dysmorphic features, mental retardation, behavioural disorders, seizures predisposition and other congenital abnormalities. Arterial hypertension is not a characteristic feature of 12p trisomy, although congenital heart defects are reported. In this case report, we present a young patient with incomplete trisomy 12p, analysing some characteristics of this disease that have not been previously described in literature.
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PMID:Trisomy of the Short Arm of Chromosome 12 Associated with High Cardiovascular Risk: A Case Report. 3080 48