Familial occurrence of 18q-

Summary An unusual segregation of the partial long arm deletion of a chromosome 18 is reported. This aberration was found in the feeble-minded mother and in her 4 daughters. The fifth child has XXY-Klinefelter's syndrome. The carriers of 18q — in this family reveal small stature, microcephaly, and mental deficiency in the range from feeble-minded to severe imbecility. Other characteristic features commonly found in patients with 18q — syndrome, as mid-face retraction, downward slanting mouth, heart defect, and atretic ear canals were not observed.     

The dermatoglyphics of the 18q- syndrome

The dermatoglyphics of three patients with an 18q – karyotype are reported. Considering the total of 20 cases now known, this deletion definitely affects the dermatoglyphic phenotype of the distal part of the palm resulting in complex configurations in this area. The fingers of these cases display a high frequency of large composite patterns.     

A case of 18q- in a family with a translocation t(6p+;18q-), identified by the Giemsa-banding technique

Summary In a male infant with multiple congenital malformations a deletion of the long arm of chromosome No. 18 was identified by means of the A.S.G. technique. His mother and sister were balanced heterozygotes with the karyotypes 46,XX,t(6p+;18q-).

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Zusammenfassung Bei einem männlichen Neugeborenen mit multiplen Mißbildungen surde mit der ASG-Technik eine Deletion des langen Armes eines Chromosomes 18 identifiziert. Mutter und Schwester des Patienten waren balancierte Heterozygoten mit dem Karyotyp 46,XX,t(6p+;18q-).

     

18q- Syndrome resulting from a tdic(14p;18q)

Summary A case of 18q- syndrome due to a de novo tdic(14p;18q) is presented. The interest of this observation lies in the rarity of stable dicentric chromosomes arising from reciprocal translocations between autosomes.     

Molecular analysis of the 18q- syndrome--and correlation with phenotype.

Seven individuals with deletions of the distal long arm of chromosome 18 were evaluated at the clinical, cytogenetic, and molecular levels. The patients had varying degrees of typical clinical findings associated with the 18q- syndrome. Cytogenetic analysis revealed deletions from 18q21.3 or 18q22.2 to qter. Somatic cell hybrids derived from the patients were molecularly characterized using ordered groups of probes isolated from a chromosome 18-specific library. In general, the size of the deletion could be correlated with the severity of the phenotype. Based on the clinical pictures of these seven patients, a preliminary phenotypic map for the clinical features associated with deletions of the distal portion of the long arm has been generated. Furthermore, genes previously localized to 18q21 were mapped relative to the chromosome breakpoints present in these patients.     

Direct transmission of the 18q- syndrome from mother to daughter

A 34-year-old mother presented moderate mental retardation, short stature, microcephaly, and characteristic facial dysmorphism. Her 12-year-old daughter manifested moderate mental retardation, short stature, microcephaly, dysplastic external ear canals, hearing impairment, and characteristic facial dysmorphism. Cytogenetic analysis of the family revealed a normal karyotype, 46,XY, in the father, and a 46,XX,del(18)(q22.2) karyotype in both mother and daughter. Molecular marker analysis determined direct transmission of the distal 18q deletion from mother to daughter. The present case provides evidence of fertility of the affected females and a mother-to-daughter direct transmission in the familial 18q- syndrome. Identification of affected females with the 18q- syndrome should include genetic counseling of possible direct transmission and consideration of birth control or prenatal genetic testing at reproductive age.     

The 11q- syndrome

Summary An eighth case of terminal deletion of the long arm of chromosome eleven (11q-) is reported to emphasize both the distinctive facies, but otherwise non-specific nature of this disorder, and the female preponderance of affected patients. Growth and mental retardation, congenital heart disease and telecanthus are the other most constant features. The authors' experience with 3 unrelated cases in less than 2 years suggests that this syndrome is underdiagnosed.     

Partial trisomy 16q-

Summary A 5-month-old female was found with a 16q-trisomy; her mother was the carrier of a balanced translocation 46,XX,t(15p+;16q-)(15p12;16q11). This is the first report in the literature of a liveborn with this chromosome abnormality.