The cloned butyrylcholinesterase (BCHE) gene maps to a single chromosome site, 3q26.

Human tissues have two distinct cholinesterase activities: acetylcholinesterase and butyrylcholinesterase. Acetylcholinesterase functions in the transmission of nerve impulses, whereas the physiological function of butyryl-cholinesterase remains unknown. An atypical form of butyrylcholinesterase or the absence of its activity leads to prolonged apnea following administration of the muscle relaxant suxamethonium. Inheritance of these butyrylcholinesterase variants is consistent with the enzyme activity being encoded in a single autosomal locus, BCHE (formerly CHE1 and E1), which has been assigned to chromosome 3. Previous in situ hybridization of a BCHE cDNA probe gave evidence of homologous sequences at 3q26 and 16q11-q23, raising the possibility of more than one locus coding for butyrylcholinesterase [H. Soreq, R. Zamir, D. Zevin-Sonkin, and H. Zakut (1987) Hum. Genet. 77: 325-328]. Using a different cDNA probe hybridized in situ to 46,XX,inv(3)(p25q21) metaphase chromosomes, we report here the localization of BCHE to a single autosomal location: 3q26.

Complementation by two non-homologous recombinant chromosomes 3.

The first example known to us of complementation by two non-homologous chromosomes 3 is present in the karyotype of a phenotypically normal brother of an inv(3)(p25q21) carrier. The normal chromosomes 3 are replaced by two complementary recombinant chromosomes 3. The longer recombinant duplicates 3q21-qter and is deficient for 3p25-pter. It is identical to the recombinant inherited by infants born with multiple congenital anomalies to inv(3)(p25q21) carriers. The shorter recombinant duplicates 3p25-pter and is deficient for 3q21-qter. This recombinant has previously been observed only in prometaphase spreads from sperm of an inv(3) carrier from the same kindred. Theoretically it is possible for the carrier of these complementary recombinant chromosomes 3 to produce sperm carrying either a normal 3, or the inversion 3, which could then fertilize an egg carrying a normal 3 followed by normal fetal development. However, the spouse of our propositus reported one first trimester spontaneous abortion, followed by no recognized pregnancy over the next 12 years of marriage.

Blood groups in Newfoundlanders.

Data are presented on 30 high and low incidence antigens and on the distribution of the alleles of 14 blood group systems in a random sample of Newfoundlanders. The distribution of alleles in Newfoundland was compared to founder populations where possible and to the Canadian Caucasian population in general; no significant differences were found. Six rare alleles were observed (IN*a, NFLD, TAR, RH*x, RH*w, RH*V) in a population of 234 individuals. A high incidence of rare alleles has been reported in other isolate populations.

Updating genograms in the practice of preventive medicine.

Family physicians uncover clues to genetic risk while they routinely sketch and add to patients' genograms. A symbolic international language identifies health conditions and shows inter- and intra-generational relationships of mating and descent. Time allotted to reviewing the genogram and follow-up carried out by the family physician and/or through referral to a genetics clinic lie well within the mandate to practise preventive medicine. Such vigilance is fundamental to the unwritten agreement between the family and the family physician to delay, moderate, or avoid health crises.

Transforming Theory into Preventive Genetics in rural Communities.

Family physicians are at the frontier in health promotion. They have opportunity to identify many familial genetic risks prior to health crises. Early diagnosis allows time to discuss choices: schedules for screening, change of diet, preventive drug treatment, and/or reproductive alternatives. Investigation of risk is less time consuming when families already have a general awareness of how genetic disease is inherited. In geographic areas underserved by genetics clinic staff, we are using CEIC job-development monies to train laypeople to organize community workshops on health and "family trees". Family physicians, together with informed laypeople, succeed in transforming genetic theory into practice.

Segregation of marker loci in families with an inherited paracentric insertion of chromosome 9.

Cytogenetic, enzyme dosage, serological, and electrophoretic analyses of blood samples from members of three Newfoundland kindreds in which one specific paracentric insertion chromosome inv ins(9)(q22.1q34.3q34.1) is segregating provide data indicating that ABO lies in 9q22.1-q34.3, AK1 in 9q34.1-q34.3, and ORM in 9q34.3-qter.

Seasonal variation of neural tube defects in Newfoundland and elsewhere.

In Newfoundland, babies with anencephaly are conceived most often in January, and those with spina bifida in August. These and previous observations suggest that (1) seasonal fluctuations are greatest when the population frequency is neither very high nor very low, and that (2) the peak season for conception of anencephalic babies may occur in any season except August-November in various populations, whereas for spina bifida seasonal peaks are confined almost exclusively to May-August.

Familial X-linked ichthyosis, steroid sulfatase deficiency, mental retardation, and nullisomy for Xp223-pter.

Steroid sulfatase (STS)-deficient X-linked ichthyosis was diagnosed in a man with short stature and mental retardation. His generation includes five similarly affected male members. A translocation chromosome is segregating in this Newfoundland kindred. The proband's mother and grandmother have normal skin and are of normal intelligence. From his carrier mother, the proband inherited an X short arm (Xp) to Y long arm (Yq) translocation chromosome, with the entire Y short arm and the X short arm terminal segment deleted (Xp223-pter). His cells are completely deficient in STS activity, confirming assignment of the STS locus to Xp223-pter. Effective management of his ichthyosis included treatment with 6% salicylic acid gel under plastic occlusion and removal of the scales by scrubbing.

A "new" low incidence red cell antigen, NFLD.

A "new" low incidence red cell antigen, NFLD, is described. It was found in a Caucasian family and is inherited as an autosomal dominant. The antigen is not part of the AB0, MNSs, Duffy, Kidd, or Yt blood group systems and probably does not belong to the Rh or Kell blood group systems.

Duplication 9q34 syndrome.

Phenotypic, karyotypic, and developmental homology between affected children of carriers of an inverted insertion (9) (q22.1q34.3q34.1) led to recognition of a new chromosome syndrome: dup 9q34. Individuals with dup 9q34 have slight psychomotor retardation, understand simple directions, and acquire a limited vocabulary. In childhood, many are hyperactive. Clinical features include low birth weight, normal birth length, and initial poor feeding and thriving. Musculo-skeletal systems are affected: there are joint contractures, long thin limbs, and striking arachnodactyly. There is abnormal implantation of the thumb, increased space between the first and second fingers, and excess digital creases. Marfan syndrome was a provisional diagnosis for several cases prior to cytogenetic analysis. Cardiovascular and ocular systems are minimally affected, erythema and heart murmurs occur, and ptosis and strabismus are frequent, but lens dislocation is not observed. Features at birth include: dolichocephaly, facial asymmetry, narrow horizontal palpebral fissures, microphthalmia, prominent nasal bridge, small mouth, thin upper lip with down-turned corners, and slight retrognathia. In older children, retrognathia is diminished and the nose becomes long and narrow. The new culture and chromosome banding techniques enable sorting of cases with the distal dup 9q phenotype into two groups. The cases with a longer dup 9q are more likely to develop with life-threatening congenital anomalies. The cases with the shorter dup 9q34 have a less severe long-term prognosis and will benefit, together with their parents, from special education. Female carriers of the inv ins(9) (q22.1q34.3q34.1) have about a 31% risk in each pregnancy to conceive a fetus affected by the dup 9q34 syndrome. A comparable figure is not yet available for male carriers.

Familial, EsD-linked, retinoblastoma with reduced penetrance and variable expressivity.

We report an example of four generation familial retinoblastoma in which there are three distinct categories of RB gene expression: frank retinoblastoma, unilateral or bilateral; retinoma; and no visible evidence of retinal pathology other than normal degeneration with age. Two large sibships derived from matings informative for RB and EsD provide strong confirmatory evidence for tight linkage between these loci (P = 0.0002), and thus assignment of RB to chromosome 13q14. There is a striking difference (P less than 2%) in RB penetrance between the two principal generations, which suggests that an additional epistatic, host-resistance gene may also be segregating within the family.

Assignment of the red cell antigen, Targett (Rh40), to the Rh blood group system.

Statistical and serological evidence from a large kindred and two unrelated adults indicates that Targett (Tar) is an antigen in the Rh blood group system and that its presence is assocciated with a weak expression of the Rh antigen D. In the numerical notation the Tar antigen is designated Rh40.

Spreading of inactivation in an (X;14) translocation.

In the KOP translocation, t(X;14)(q13;q32), virtually the entire long arm of the X has been translocated to the end of the long arm of chromosome 14. Meiotic secondary nondisjunction in a female balanced carrier of the translocation has led to a son with two der(14) or 14-X chromosomes. The normal X chromosome is late replicating in the mother. One of the two 14-X chromosomes is late replicating in the son, with heavy terminal labeling of all but the centromeric end of the chromosome. This suggests that genetic inactivation has spread from the Xq segment of the translocation chromosome to at least two thirds of the segment derived from chromosome 14, and that the remaining proximal segment of chromosome 14 is possibly still genetically active. These findings provide an explanation for the phenotype: Klinefelter syndrome plus a few mild malformations that are sometimes seen in this syndrome but are also seen in duplication of the proximal portion of chromosome 14. Although the proband has a duplication of virtually an entire chromosome 14, 14(pter leads to q32), the phenotypic effect of the autosomal duplication has been mostly nullified by the spread of inactivation.

Reversible dysfunction of T-lymphocytes in common variable immunodeficiency.

A 30-year-old man with recurrent sinopulmonary infections, eventually fatal, was found to have common variable immunodeficiency. In addition to low serum immunoglobulin concentrations he also had lymphopenia and cell-mediated immunodeficiency as shown by cutaneous anergy and a poor lymphocyte response to phytohemagglutinin (PHA) in vitro. However, intradermal injection of PHA produced a vigorous cutaneous response, showing that some cell-mediated responsiveness remained. The responsiveness of his lymphocytes to PHA was restored towards normal (confirmed by chromosome studies) by the addition of a small number of normal leukocytes to cultures; thus a reversible functional defect in his T-lymphocytes was revealed. Experiments indicated that the defect was cellular and not due to serum factors and it was concluded that normal leukocytes restored a missing factor to the patient's T-lymphocytes. Although counts of macrophage precursor cells in the bloodstream were low, thus contributing to the immunodeficiency, this could not have caused the reduced PHA response. Several relatives of this patient had lymphoma; two cousins had common variable immunodeficiency.

The 9p- syndrome.

Six patients (4 females and 2 males) with terminal deletion of the short arm of chromosome 9 distal to band p22 are described. The disorder constitutes a clinically identifiable syndrome consisting of mental retardation, sociable personality, trigonocephaly, mongoloid eyes, wide flat nasal bridge, anteverted nostrils, long upper lip, short neck, long digits mostly secondary to long middle phalanges, and predominance of whorls on fingers. The findings suggest that the clinical features are antithetical to the trisomy 9p syndrome. The deleted chromosome segment is relatively small and could be easily overlooked. It is hoped that this delineation of clinical features seen in 9,p- patients may help in focusing attention on the small deletion.

Chromosome 3 duplication q21 leads to qter deletion p25 leads to pter syndrome in children of carriers of a pericentric inversion inv(3) (p25q21).

Close phenotypic similarity between two cases carrying a rec(3) dup q,inv(3) (p25q21), 12 additional infants from the same inv (3)(p25q21) kindred who lived less than 1 year, and eight cases studied in other medical centers has led us to postulate the existence of a distinct chromosome 3 duplication-deletion syndrome. In the presence of trisomy for (3)q21 leads to qter and monosomy for (3)p25 leads to pter, the facial dysmorphy is unique: a distorted head shape due to irregular cranial sutures, thick low eyebrows, long eyelashes, persistent lanugo, distended veins on the scalp, hypertelorism, oblique palpebral fissures, a very short nose with a broad depressed bridge and anteverted nares, protruding maxilla, thin upper lip, micrognathia, low-set ears, and a short webbed neck. Port-wine stains, congenital glaucoma, cloudy corneas, cleft palate and harelip also occur frequently. Each infant has difficulty sucking and swallowing. Congenital anomalies of the cardiovascular system, of midgut rotation, and of the urogenital system are noted for the infants who died neonatally. Most frequent is a ventricular septal defect, followed by atrial septal defect, patent ductus arteriosus, patent foramen ovale, and coarctation of the aorta. Omphalocele, umbilical hernia, hyperplastic kidneys, polycystic kidneys, double ureter, hydro-ureter, hydronephrosis, and undescended testes often occur. The extremities are short in proportion to the length of the trunk. Clinodactyly, coxa valga, talipes, and spina bifida are frequently observed.