Jan B. Bijlsma

Localization of HLA on the Short Arm of Chromosome 6

SummaryA detailed marker gene study in a large Dutch kindred segregating for a reciprocal translocation between the chromosomes 6 and 20, t(6;20) (p21;p13), revealed a close linkage between the HLA genes and the breakpoint on the short arm of 6. During this study an apparent peak lod score of 2.9 was obtained at a recombination value of 0.05 for a linkage between HLA and the breakpoint, indicating that the chromosomal region, carrying the HLA genes, is situated near the breakpoint in band 6p21 close to the transition to 6p22.

Partial trisomy 10q

SummaryFive cases from two nonrelated families with partial trisomy 10q due to a reciprocal translocation t(10;17)(q25;p13) and t(10;11)(q24;q23), respectively, are reported. The phenotypic findings are compared with those of 17 previously published cases; the clinical data justify the conclusion that cases with trisomy 10q show a specific syndrome of mental retardation and malformation characterized by psychomotor retardation, growth retardation, hypotonia, high forehead, flat face, fine and arched eyebrows, antimongoloid slant of the eyes, narrow palpebral fissures, hypertelorism, short nose, bowshaped mouth, short neck, (kypho)scoliosis, and in some cases microcephaly.

Double translocation t(7;12),t(2;6) heterozygosity in one family

SummaryDouble translocation heterozygosity t(2;6),t(7;12) in three generations of a Dutch family is described: the segregation of a double translocation in more than one generation has not been previously published. The index case was a 16-year-old mentally retarded boy with partial trisomy 12p who showed several dysmorphic features such as high prominent forehead, flat face, flat and short nose bridge, short nose, dysplastic ears, prominent lower lip, and several skeletal abnormalities. Based on the findings in this patient and those in nine other cases, the existence of a specific trisomy 12p syndrome is postulated.

Two cases with different deletions of the long arm of chromosome 7.

Two mentally and physically retarded girls, one with an interstitial deletion 7 (pter leads to q21::q32 leads to qter), and the other with an interstitial deletion 7 (pter leads to q11::q22 leads to qter), are described. Their clinical features are compared with those of 11 earlier reported cases with a deletion 7q. The Hageman factor, the locus of which is assigned to the distal part of 7q, was in both cases within normal limits. The data available do not justify the delineation of a specific clinical syndrome.

Partial trisomy 6p due to familial translocation t(6;20)(p21;p13)

SummaryCytogenetic findings in a case of partial trisomy 6p due to a translocation t(6;20)(p21;p13) and eleven balanced translocation heterozygotes are described.The clinical data of the proposita are compared with those of five other published cases. A partial trisomy 6p syndrome is postulated, characterized by: low birth weight, psychomotor retardation, craniofacial abnormalities (such as high prominent forehead, large fontanel, wide sagittal suture, blepharoptosis, low-set and/or malformed ears), congenital heart malformation, small kidneys, and proteinuria. Linkage studies have shown that the breakpoint in chromosome 6 involved in this translocation is close to the HLA gene cluster.

Duplication deficiency syndrome in familial translocation (2q-; 5p+)

SummaryThis paper describes a female patient with a duplication deficiency syndrome resulting from a hitherto undescribed familial translocation (2q-; 5p+). In addition to marked mental retardation, the patient shows multiple somatic abnormalities.The chromosomal anomaly was traced in a balanced form in three preceeding generations. Besides a detailed description of clinical data, the results of chromosomal, familial and genetic studies as well as data on growth and development are discussed.

Partial monosomy 10p syndrome.

A 7-year-old girl is described with a de novo deletion of the short arm of chromosome 10 (qter→p13:). The clinical features of: mental retardation, a large asymmetric head, antimongoloid slant, exophthalmos, epicanthus, ptosis, abnormal ears, pectus excavatum and widely spaced nipples are compared with those of five earlier reported cases with a deletion 10p. The data available suggest the existence of a clinically recognizable monosomy 10p syndrome.

Direct giemsa-banding pattern analysis of human chromosomes by means of a television microdensitometer: The Quantimet 720 D

SummaryA method for recording G bands of chromosomes directly from slides by means of the Quantimet 720 D, is presented.ZusammenfassungEs wird über eine Methode berichtet, mit Hilfe des Quantimet 720D G-Banden von Chromosomen direkt aus den Präparaten zu registrieren.