L. N. Went

Genetic linkage between erythrokeratodermia variabilis and Rh locus

SummaryA genetic linkage study was performed in a large Dutch kindred with erythrokeratodermia variabilis (EKV, McKusick no. 13320). The autosomal-dominant trait appeared to segregate rather consistently with the cde (r) gene complex of the Rh system. Only one recombinant was found amongst 27 informative individuals. Lod score calculations gave strong evidence for close linkage between the loci for EKV and Rh (with a maximum lod score of 5.55 at a recombination fraction of 0.044).

The genetics of tritan disturbances

SummaryTritan (blue-green) colour vision disturbances have been found in 79 individuals in six families, revealing an autosomal dominant mode of inheritance with a wide variability of test results within families. Evidence is presented that it is—in contradistinction to the X-chromosomally inherited redgreen defects—incorrect to make a subdivision between dicromasia (tritanopia) and anomalous trichromasia (tritanomaly). On the basis of three small screening series, totalling 1900 individuals, the frequency of tritan disturbances in estimated to be around 2 per 1000. Seven males have been observed carrying both inherited tritan and red-green defects.

Further evidence for localization of the gene of erythrokeratodermia variabilis

SummaryClose genetic linkage between erythrokeratodermia variabilis (EKV) and the Rh blood group system has been reported by our group. Here we describe the results of a linkage analysis in another EKV kindred, in which the disease segregated with the CDe genotype. Among 18 informative individuals, 1 recombinant was found. A maximum lod score of 4.21 was calculated at a recombination fraction of 0.03–0.04. Addition of this lod score to the earlier reported results gives a maximum lod score of 9.93 for linkage between EKV and Rh at a recombination fraction of 0.03 (95% confidence limits 0.008–0.11).

A family with apparently sex-linked optic atrophy.

A family is described in which a probable new form of sex-linked optic atrophy was found in eight individuals. Some additional neurological abnormalities were noted. Results of studies of the Xg blood group excluded close linkage between the optic atrophy and Xg genes. As a probable coincidence, Huntingtons chorea was found in a side branch of the family.

A Search for Associations between Genetical Polymorphic Systems and Physical, Biochemical and Haematological Variables

A total of 811 young people (16–27 years) of both sexes were studied in a health screening program during which multiple biochemical, haematological, and physical variables were measured. In addition,

A family with sex linked optic atrophy

A large family in which 8 males are affected with apparently sex linked optic atrophy is described. The disease has been present since early childhood, and the visual acuity ranges between 1/60 and 0.4. The fundi are very typical: pale optic discs, frequently with cupping and an abnormal vascularity. In all cases visual fields are normal on the periphery with somewhat enlarged blind spots or paracentral scotomata in the older patients.All patients were investigated electro-ophthalmologically. The clearly abnormal VECPs and the very probably normal ERG in the youngest patient indicate that the disturbance in the conductive system is prior to that of the retina. Fluorescence angiography revealed the typical appearance of optic atrophy.In addition to the typical findings of the optic atrophy also neurological abnormalities varying between very mild to more severe were observed in the patients. Neurological examination revealed definitely abnormalities but classification was not possible. Symptoms of Huntingtons Chorea were not found.Ophthalmological, electro-ophthalmolocigal, fluorescein-angiographic and neurological studies in the female carriers did not reveal any abnormalities.An analysis of all other types of optic atrophy described hitherto in the literature did not reveal comparable cases to the ones seen in our family.

Haemoglobin A2-NYU in the Netherlands

A minor haemoglobin variant in a Dutch family has been characterized as Hb A2-NYU:α2δ212Asn→-Lys. Arguments are presented, based partially on dat

Unilateral colour vision disturbance. A family study

A man with a unilateral colour vision defect is reported. The defect of his right eye can best be defined as lying between deuteranopia and extreme deuteranomaly. The left eye was unusual in that it gave a normal Rayleigh equation on the anomaloscope but abnormal readings, classical for red‐green defectives, with the Ishihara test plates. Two cousins and an uncle had bilateral colour vision defects closely resembling the defect from the right eye of the proband. Various explanations were sought for the findings, but ocular pathology, abnormal sex chromosome numbers, and mosaicism with Lyonization as well as somatic back mutation all seem to be unsatisfactory as such.

Frequencies of Different Types of Colour Vision Defects in the Netherlands

Two different population samples in Holland--one consisting of 1,093 boys from a technical school and the other of 493 male and 416 female students--were analysed for the presence of red-green colour vision defects. A total percentage of 7.3 for the male population was found. Based on the combined results of the Ishihara and HRR pseudoisochromatic plates, the Farnsworth 15-hue test and the anomaloscope, a subdivision of the deuteranomalous individuals into 3 subgroups is made. It is suggested that the differences between these groups may be genetic in nature and that the actual number of different genetic entities may still be greater.

Familial benign hypercalcaemia (FBH; McK. No. 14598, 1983): Linkage studies in a large Dutch family

SummaryBy screening 27 hypercalcaemic and 21 normocalcaemic subjects in a large Dutch pedigree with familial benign hypercalcaemia (FBH; McK. No. 14598) (McKusick 1983) for more than 35 genetic markers, it was found that linkage of FBH can be excluded at about 25 centimorgans (cM) from GM, 20 cM from ABO, 15 cM from MNS and HLA, 10cM from JK and PI, and 5cM each from ACP1, AK1, ADA, GPT1, and PGP.