We report the first case of maternal uniparental disomy of chromosome 14 in humans. The male proband inherited a balanced 13;14 Robertsonian translocation from his mother. Molecular studies showed that neither chromosome 14 was of paternal origin. The proband is of above average intelligence, but he has hydrocephalus, a bifid uvula, premature puberty, short stature, and small testes. It is not known if the clinical findings are related or coincidental to the uniparental disomy.In 1980 Engel' recognised that, because of the relatively large proportion of human gametes that have an additional or missing chromosome, there was a possibility of fertilisation involving two complementary aneuploid gametes resulting in a euploid conceptus in which both members of one chromosome pair came from the same parent. He called this phenomenon uniparental disomy. Later in the same year the first two examples of uniparental disomy were described.2 3 Both were women referred for recurrent abortions who were found to have a Robertsonian translocation t(22;22) that had been inherited from their phenotypically normal mother. These exceptional women must have arisen by the fertilisation of an egg carrying the translocation by either a sperm nullisomic for chromosome 22 or by a normal sperm, the resulting trisomy 22 conceptus losing the paternal 22 very early in development. Both women were phenotypically normal and it can therefore be concluded that maternal uniparental disomy

Three patients with mosaicism and a cell line containing a small ring (X) chromosome are described. Their phenotype is similar to several previously reported patients with a 45,X/46,X,r(X) karyotype and a phenotype far more severely affected than expected in Turner's syndrome. The clinical picture includes mental retardation, a facial appearance reminiscent of the Kabuki make up syndrome, and limb anomalies. Some of the patients also had streaky hyperpigmentation of the skin in a pattern suggesting dermal mosaicism. It (fig 1).The baby subsequently suffered from recurrent wheezing and chest infections. Her developmental and growth delay persisted. At the age of 33 months her length was 3-4 SD and her weight 2-3 SD below the mean for her age. She died at the age of 35 months.The cytogenetic results have been reported in full by Jacobs et al.1 Briefly the majority of the patient's blood leucocytes had a 45,X constitution, the X being inherited from the father. However, 15 of 200 cells had a ring (X) smaller than a G group chromosome while nine cells had two ring chromosomes, one smaller than a G group and one minute. In situ hybridisation with the X centromere probe pSV2X5 confirmed that both ring chromosomes were derived from X chromosome material, presumably that of the mother. Studies of the replication status of the two ring chromosomes were attempted using a terminal pulse of BrdU, but both rings were found to be too small to give accurate results. CASE 2Case 2 (89-1479) was the second child of a healthy 32 year old mother and 33 year old father. The pregnancy was complicated by polyhydramnios and she was born after spontaneous labour at 37 weeks' gestation, weighing 2950 g. Limb abnormalities were noted at birth. She had a short right arm and the right hand had a thumb and two fingers only, all digits being broad and short. The left arm and hand were normal in size but all the digits were broad and short. The right leg and foot were normal but the left femur was slightly short and the left fibula was absent. There was syndactyly of the lateral three toes. The unequal leg length necessitated a below knee amputation at 8 years.As a baby she fed badly owing to palatal incoordination and had slow weight gain.

Paternal duplications of distal 11p result in Beckwith Wiedemann syndrome (BWS), whereas maternal duplications have not, to our knowledge, been reported previously in the literature. We present three unrelated patients with maternal duplications of distal 11p. Patient 1 is a 31-year-old female with a de novo inverted duplication of distal 11p, i.e. inv dup del(11)(qter-->p15.5::p15.5-->15.3); this rearrangement was shown to be maternal in origin by microsatellite analysis and methylation-specific polymerase chain reaction. Patient 2 is a 4-year-old female with a derived chromosome 20, which arose from adjacent 1 malsegregation of a maternal t(11;20)(p15.3;q13.33). Patient 3 presented as an intrauterine death with trisomy for the majority of chromosome 11p as a result of 3:1 segregation of a maternal t(11;15)(p11.2;q11.2). In view of the imprinted status of this region, it is pertinent that none of our patients showed features of BWS; indeed, all had growth retardation, in contrast to the overgrowth characteristic of BWS. It is of note that, of the living patients, Patient 1 went into early puberty at 9.5 years and Patient 2 showed breast development in infancy. Both patients shared some dysmorphological features, namely short palpebral fissures, a prominent nasal tip, a short philtrum and 5th finger clinodactyly.

The results of a cytogenetic and molecular reinvestigation of a series of 52 patients with Turner's syndrome are reported. No evidence of Y chromosome material was found among the patients with a 45,X constitution but two patients were found to have a cell line with a r(Y) chromosome which was previously thought to be a r(X). The parental origin of the single X in the 45,X patients was maternal in 69% and paternal in 31%, a similar ratio to that seen among spontaneously aborted 45,X conceptuses. This suggests that X-chromosome imprinting is not responsible for the two grossly different phenotypes associated with a 45,X chromosome constitution. Approximately half of the structurally abnormal X chromosomes were maternal in origin and half paternal. This observation is consistent with either a meiotic or post-zygotic mitotic origin and at variance with the predominantly paternal origin reported for autosome structural abnormalities.