Sibylle D. Flatz

Preferential Maternal Derivation in Inv Dup(15) Analysis of Eight New Cases

SummaryEight patients are reported with a de nov extra inverted duplicated chromosome 15. The abnormal chromosome was considered to be the same in all cases, but its precise delineation remained uncertain and was defined as either 15qter→15q12::15q12→15pter or 15pter→15q11::15q13→15pter. Analysis with various techniques of the satellite regions of the bisatellited chromosomes demonstrated maternal derivation in six and paternal derivation in one of the seven families. A nonsister chromatid exchange between the two homologous chromosomes 15 is considered a likely origin of the inv dup(15) in the cases with maternal derivation; in the only case of paternal derivation, however, the abnormal chromosome originated from one single chromosome 15. The clinical findings confirm that patients with inv dup(15) have mental and developmental retardation and are frequently affected by seizures, while severe physical malformations are absent.

Prevalence of primary adult lactose malabsorption in three populations of northern China

SummaryLactose absorption capacity was examined in 641 apparently healthy adolescents and adults (447 males and 194 females with an average age of 22.9 years and an age range of 16–46 years) using a field version of the lactose tolerance test with breath hydrogen determination. In the total sample, 89 lactose absorbers and 552 lactose malabsorbers were identified. Lactose malabsorption was most frequent in a subgroup of Han (Chinese) from northeastern China (229 of 248 subjects, 92.3%). Among 198 Mongols from Inner Mongolia, there were 174 lactose malabsorbers (87.9%). The frequency of lactose malabsorption was lowest in a group of Kazakhs, traditional herders from the northwestern region of Xinjiang (149 of 195 subjects, 76.4%). Reported symptoms of lactose intolerance were significantly more frequent in lactose malabsorbers. The findings in northern Han are similar to the reported lactose malabsorption frequency in southern (mainly overseas) Chinese, and correspond with the absence of animal milk from traditional Chinese diets. The relatively low prevalence of lactose malabsorption among the Kazakhs suggests that lactose persistence may be frequent in herding pastoralist populations of southwest Asia.

Partial trisomy 1q due to tandem duplication.

Sirs, Rehder & Friedrich (1979) recently described partial trisomy l q syndrome and summarized the characteristic symptoms. These observations may be supplemented by the case of a boy (now aged 9 months) in whom similar clinical features enabled us to identify a de novo elongation of the long arm of chromosome 1 as tandem duplication. The boy is the second child of healthy, 21-year-old parents. He was born by breech delivery after 37 weeks of gestation. His birth weight was 2310 g, and his length 46 cm. Growth and development were delayed. Physical examination at the age of 6 weeks revealed a hydrocephalic configuration of the skull with large fontanelles and a wide open sagittal suture, a prominent forehead and a small triangular face with a small, pointed chin. There was mid-facial hypoplasia, deeply set eyes, upward slanting of the palpebral fissures and biepharophimosis. The bridge of the nose was depressed, the nose was beaked a t the tip with a long nasal septum and anteverted nostrils. The

A study of lactose absorption capacity in twins

SummaryLactose absorption capacity was determined by lactose tolerance tests with breath hydrogen determination in 102 healthy, adult, Hungarian pairs of twins in order to test monogenic Mendelian inheritance of the absorptive lactase phenotypes, lactose absorber and lactose malabsorber. Of the total, 52 pairs were monozygous (MZ) and 50 dizygous (DZ) twins of indentical sex. All MZ twins were concordant with respect to lactase phenotype. Among DZ twins, the distribution of lactase phenotypes was in agreement with Hardy-Weinberg expectations derived from the frequencies of the hypolactasia gene in DZ and MZ twins, and in the general Budapest population.In the second part of the study, three commonly used methods of lactose tolerance testing, the blood glucose, the blood galactose, and the breath hydrogen tests, were compared in 49 pairs of twins concordant for lactase phenotype. Blood galactose concentration showed the greatest and only significant difference between the intrapair correlation coefficients of MZ and DZ, and no overlap between lactose absorbers and lactose malabsorbers. The intrapair correlation coefficients of peak breath hydrogen concentration in MZ and DZ twins did not significantly differ from zero, but the resolution of lactase phenotypes was satisfactory. Differences in glucose absorption and concentration in lactose absorbers and malobsorbers overlapped considerably, and among lactose absorbers correlation coefficients in DZ were higher than in MZ twins. In MZ and DZ twins, the difference in concordance and constancy of lactose intolerance symptoms was not significant.

Distribution of physiological adult lactase phenotypes, lactose absorber and malabsorber, in Germany.

SummaryA total of 1805 apparently healthy, adult and adolescent Germans (1572 males and 233 females with a mean age of 20.3 years) were examined for lactose absorption capacity employing a field version of the breath hydrogen (H2) test. The diagnostic parameter, maximal change of breath hydrogen concentration 120 or 150 min after a load of 50 g lactose, showed a bimodal distribution, separating lactose absorbers (n-1537, 85.2%) and lactose malabsorbers (n=268, 14.8%). The distribution of the adult lactase phenotypes was independent of age, sex, and educational status. The incidence of gastrointestinal symptoms after lactose administration demonstrated the incongruity of lactose malabsorption and lactose intolerance. In addition to grouping by residdence, the probands were classified according to the birthplaces of their grandparents in order to reconstruct the distribution pattern of the lactase phenotypes prior to World War I, a period of relative population stability. Considerable differences in the frequency of lactose malabsorption were found in regions corresponding to traditional ethnic groups within the German population: northwest Germany 6–9%, west and south 13–14%, southwest 23%, east (including formerly German territories east of rivers Oder and Neisse) 22%. These differences are discussed with reference to population history. The present fairly even distribution of the lactase phenotypes in West Germany is the result of internal migrations at the end of World War II.

DNA haplotypes and frameworks linked to the β-globin locus in an Austro-Asiatic population with a high prevalence of hemoglobin E

SummaryDNA haplotypes (HT) and frameworks (FW) linked to the β-globin locus were determined by restriction fragment analysis using eight restriction enzymes on chromosomes bearing the HbA gene (HBB*A) or the HbE gene (HBB*E) in the So, an Austro-Asiatic population of northeast Thailand with an HBB*E frequency near 0.5. All HBB*E genes were present with FW2, and only two haplotypes were observed (25 HT 27-2,-+-++++-; 10 HT 41-2, +----++-). In a control group from the general population of Northeast Thailand the HT distribution was more diverse, and 2 of 20 HBB*E genes were present in FW 3. High frequencies of HBB*E in FW 3 in Southeast Asia are apparently limited to the Khmer population of Cambodia. There were no differences in the hematologic parameters in subjects homozygous for HBB*E/FW2 or HBB*E/FW3.

Mitotic disturbance associated with mosaic aneuploidies.

SummaryThe association of various unsystematic aneuploidies with premature centromere division (PCD) was observed in a patient with conspicuous clinical features and combined immunodeficiency. Trisomies and monosomies of almost all autosomes and gonosomal aberrations were found separately or in combination in a majority of the probands lymphocytes and fibroblasts. The chromosome number varied from 44 to 50. A high proportion of the metaphases showed PCD or had the appearance of C-anaphases. These findings probably represent a new mutant affecting mitosis and causing mosaic aneuploidies.

Non‐fluorescent Y chromosome in a male infant with Turner's symptoms and XO/XY mosaicism

A 45,X/46,XY mosaicism was found in a male infant with stigmata of Turners syndrome but normal male external genitalia. In contrast to the Y chromosome of his father, the Y chromosome of the patient does not display either the characteristic brilliant fluorescence or the typical dark heterochromatin staining of the distal long arm. Furthermore, DNA replication in the abnormal Y chromosome was shown to be premature. Mechanisms leading to the observed abnormalities are discussed.

Partial trisomy 4q and partial monosomy 18q as a consequence of a paternal balanced translocation t(4q−;18q+)

SummaryIn a 16-month-old girl with stigmata of the 18q- syndrome, the analysis of Giemsa banding patterns displayed a chromosome 18 with an enlarged terminal band region of the long arm. The propositas father and brother also revealed an elongated chromosome 18 and, in addition, a shortened long arm of chromosome 4. These two individuals are carriers of a balanced translocation with the karyotype 46,XY,t(4q-;18q+). The proposita received the 18q+ chromosome from the father. She was partially monosomic for a terminal segment of 18q and partially trisomic for a terminal segment of 4q.

Prevalence of primary adult lactose malabsorption in Hungary

SummaryLactose absorption capacity was estimated in 820 apparently healthy, well nourished, Hungarian adults and adolescents (560 females, 260 males, aged 16–54 years) using a field version of the lactose tolerance test with breath hydrogen determination. The test identified 497 lactose absorbers with low, and 323 lactose malabsorbers with high hydrogen excretion 120–150 min after an oral load of 50 g lactose. The prevalence of lactose malabsorption in the general Hungarian sample (n=535) was 37%. In subgroups from the western and eastern Hungarian plains, frequency of lactose malabsorption reached almost 30%. It tended to be higher in Upper Hungary (ca. 40%) and in subjects stemming from former Hungarian areas in the Carpathian bend. Lactose malabsorption in a Hungarian ethnic subgroup, the Matyo (n=172), did not differ significantly from that in the general population. Among Romai (“Gypsies”, n=113), the prevalence of lactose malabsorption was significantly higher (56%). Awareness of milk intolerance was significantly more frequent, and severe symptoms of lactose intolerance during the test occurred almost exclusively in lactose malabsorbers.