Three cell line mosaicism involving structural and numerical abnormalities of chromosome 18 in a 3.5-year-old girl: 47,XX,+18/47,XX,+del(18)(q22)/46,XX.

We report on a 3.5-year-old girl with a mosaic karyotype including full trisomy 18, normal cells and a majority of cells with partial trisomy involving an extra chromosome 18 deleted at band q22. She had cardiac and CNS anomalies, dysmorphic facial features failure to thrive and developmental delay. A gastrostomy tube was placed at 2 years of age. The combination of improved nutrition and optimal developmental therapy has led to her sitting supported, attempting to stand and enhancement of her cognitive and non-verbal communication abilities. Molecular investigation of the patient and her parents using microsatellite analysis has led to the conclusion that, as expected, the additional copy of chromosome 18 constituting the full trisomic cell line is maternal meiosis I in origin. The data, however, indicate that in the trisomic cell line containing the deleted chromosome 18q, the structurally abnormal 18 was of paternal origin. We think this case is the first described with both structural and numerical trisomic mosaicism involving chromosome 18 in a liveborn infant. We propose a mechanism of origin and review the literature, comparing the clinical presentation of this case with individuals having full or partial trisomy 18.

The molecular basis of X-linked spondyloepiphyseal dysplasia tarda.

The X-linked form of spondyloepiphyseal dysplasia tarda (SEDL), a radiologically distinct skeletal dysplasia affecting the vertebrae and epiphyses, is caused by mutations in the SEDL gene. To characterize the molecular basis for SEDL, we have identified the spectrum of SEDL mutations in 30 of 36 unrelated cases of X-linked SEDL ascertained from different ethnic populations. Twenty-one different disease-associated mutations now have been identified throughout the SEDL gene. These include nonsense mutations in exons 4 and 5, missense mutations in exons 4 and 6, small (2-7 bp) and large (>1 kb) deletions, insertions, and putative splicing errors, with one splicing error due to a complex deletion/insertion mutation. Eight different frameshift mutations lead to a premature termination of translation and account for >43% (13/30) of SEDL cases, with half of these (7/13) being due to dinucleotide deletions. Altogether, deletions account for 57% (17/30) of all known SEDL mutations. Four recurrent mutations (IVS3+5G-->A, 157-158delAT, 191-192delTG, and 271-275delCAAGA) account for 43% (13/30) of confirmed SEDL cases. The results of haplotype analyses and the diverse ethnic origins of patients support recurrent mutations. Two patients with large deletions of SEDL exons were found, one with childhood onset of painful complications, the other relatively free of additional symptoms. However, we could not establish a clear genotype/phenotype correlation and therefore conclude that the complete unaltered SEDL-gene product is essential for normal bone growth. Molecular diagnosis can now be offered for presymptomatic testing of this disorder. Appropriate lifestyle decisions and, eventually, perhaps, specific SEDL therapies may ameliorate the prognosis of premature osteoarthritis and the need for hip arthroplasty.

Penile neurofibromas.

Unless omitted and underreported, penile neurofibromas are rare. Between January 2, 1982 and December 31, 1997 through the USF Regional Genetics Program we evaluated 566 propositi with suspected or clinically diagnosed neurofibromatosis (NF1, NF2, segmental NF=NF5, NF/Noonan syndrome, familial café-au-lait macules, and solitary neurofibroma, NF). These index cases were part of 32,715 families evaluated during the period. NF1 was the diagnosis in 361; 2 of them had penile NFs. A toddler presented with congenital plexiform NF of the penile shaft and another propositus developed two small subcutaneous NFs, on the penile shaft and on the left scrotal wall, respectively. A review documented 26 additional patients with penile NF. As to the pathogenesis of the NF1 lesions, a paracrine growth model including the multiple levels of regulation of expression of the NF1 gene appeared more plausible than the loss of heterozygosity (LOH) model, which ignores the complexity of the paracrine growth mechanism.

Diabetic embryopathy.

The teratogenicity of human pregestational maternal diabetes mellitus (DM), classes B-T, is beyond any doubt and leads to a spectrum of malformations known as diabetic embryopathy (DE). Gestational DM (classes A1 and A2) is not an established teratogen yet. This is linked to its late diagnosis, usually only after the 20th week, and to the incomplete understanding of the pathogenesis of DE. Since class A-T DM affects approximately 5% of all pregnancies, intensive laboratory and clinical research continues to address the numerous aspects of DE. A review of this research during 1997 and 1998 is presented for the pediatrician in order to enhance the awareness of DE and its possible role in "idiopathic" malformations for children.

Gestational diabetes mellitus (class A): a human teratogen?

Between January 1, 1982 and December 31, 1992 we evaluated 200 children of mothers with pregestational or gestational diabetes mellitus through the University of South Florida Genetics/Dysmorphology Clinics. They were a portion of the 22,100 families seen during that period. Pregnant women with diabetes mellitus were not part of this study. One hundred and fifty-two of the 200 were offspring of mothers with gestational diabetes (classes A1 and A2). Class B1 was not encountered as a subclass of gestational diabetes in this series. Twenty-four of the 152 did not have anomalies. Forty-one of the 152 had another primary diagnosis to account for their malformations. Eighty-seven of the 152 had a constellation of anomalies or solitary structural defects as seen in diabetic embryopathy. Chromosomal, monogenic, and other teratogenic causes were excluded. The observed phenotypes matched those seen in offspring of mothers with diabetes mellitus classes B2 to T. They also corroborated the animal studies, indicating that the embryopathy of gestational diabetes has a pathogenesis similar to that in classes B2 to T, and recent epidemiological studies showing a statistically significant increase of anomalies as in diabetic embryopathy in the offspring of gestational diabetes mothers. As per established obstetric practice the testing for gestational diabetes was after gestation 16 weeks. Thus, it was impossible to prove that the anomalies of the 87 propositi were due to gestational diabetes. However, the anomalies occurred during organogenesis as in the other diabetic classes, and inferred that gestational diabetes is a human teratogen. If so, common "idiopathic" malformations may be actually caused by undiagnosed maternal gestational diabetes.

New' manifestations of BOR syndrome.

Defined in 1975, branchio-oto-renal (BOR) syndrome is an autosomal dominant disorder consisting of branchial arch anomalies, hearing loss, and urinary tract malformations. It is the prototype of the non-chromosomal syndromes that have branchial arch anomalies as major clinical manifestations: BOR, branchio-otic (BO), branchio-otic-facial (BOF), and Townes-Brock syndromes. Subsequently, several clinical manifestations have expanded its phenotype. Retrospective analysis of 31020 families evaluated between January 2, 1982 and December 31, 1996 at the genetic clinics of the University of South Florida, showed seven probands with BOR/?BOR syndrome. Four of the probands and affected relatives had manifestations that further expanded the phenotype: gustatory lacrimation, hypospadias, imperforate anus, osteosclerosis, microcephaly, hypodontia, congenital vocal cord paresis, and congenital incomplete fixation of the transverse colon. Thus, BOR/ ?BOR syndrome appears to be a clinically and genetically heterogeneous multiorgan/system entity that manifests itself predominantly during organogenesis. Clinicians and researchers alike should be cognizant of the expanded phenotype and heterogeneity, while in the DNA laboratories the latter will be sorted out.

Lenz syndrome in two sisters: clinicopathologic correlations of the ocular anomalies.

BACKGROUND: The Lenz syndrome (Mendelian inheritance in Man catalog number 309,800) is a presumed X-linked recessive disorder. Major diagnostic criteria include ocular, skeletal, and urogenital manifestations. We describe two sisters and the two sons of one of them with Lenz syndrome. The eye from one boy was removed because of pain and total loss of vision, allowing histopathologic documentation of the ocular malformations. METHODS: Clinicopathologic case report. RESULTS: Two sisters in this family displayed several of the major diagnostic criteria of the Lenz syndrome. The stunted growth of the eye, and the ocular and non-ocular anomalies defines the microphthalmos as monogenic, complex, and colobomatous. CONCLUSION: The pattern of inheritance of Lenz syndrome is best explained by X-linked dominant transmission. Future reports of familial cases with an excess of affected females are needed to confirm this hypothesis.

Analysis of CpG C-to-T mutations in neurofibromatosis type 1. Mutations in brief no. 129. Online.

Neurofibromatosis type 1 (NF1) is a dominant disorder caused by mutations in the NF1 gene; approximately 100 NF1 gene mutations have been published. The CpG C-to-T transition is a frequent mutation mechanism in genetic disorders. To estimate its frequency in NF1, we employed a PCR-restriction digestion method to examine 17 CpGs in 65 patients, and also screened for a CpG nonsense transition (R1947X) that occurs in 1-2% of patients. The analysis revealed disease-related CpG C-to-T transitions (including a nonsense mutation that may be as frequent as R1947X) as well as a benign variant and another mutation at a CpG. Four patients showed CpG mutations in analysis of 18 sites (17 surveyed by restriction digest, plus the R1947X assay), including three C-to-T transitions and one C-to-G transversion. These 18 sites represent one-fifth of the 91 CpGs at which a C-to-T transition would result in a nonsense or nonconservative missense mutation. Thus, it is feasible that the CpG mutation rate at NF1 might be similar to that seen in other disorders with a high mutation rate, and that recurrent NF1 mutations may frequently reside at CpG sites.

Expanded phenotype of cranioectodermal dysplasia (Sensenbrenner syndrome)

Cranioectodermal dysplasia (CED) is an autosomal recessive condition characterized by defects of ectoderm-derived structures and characteristic bone anomalies. We report on a 27-month-old Caucasian girl with CED, pre- and postnatal growth retardation, microcephaly, hypoplasia of the posterior corpus callosum, photophobia, and aberrant calcium homeostasis. Since new traits were encountered, we reviewed all reported patients and one unpublished case and compared the frequency rates of the individual manifestations. The findings present in all patients are dolichocephaly and rhizomelia. Ectodermal dysplasia manifestations are variable. Short thorax and heart defect are inconsistent. Previously unreported anomalies include growth deficiency, delayed psychomotor development, microcephaly, photophobia, and abnormal calcium homeostasis. These clinical manifestations may facilitate the diagnosis of this condition.

Paternal exposures and the question of birth defects.

Compared to maternal exposures, little attention has been paid to the possibility of paternally induced adverse effects on fetal development. There is increasing concern, however, about the potential for male-mediated developmental toxicity brought about by exposure to teratogenic agents. This is evidenced by the number of calls regarding paternal exposures that are received by teratogen information services. In this paper, we report the experience of the state of Florida's Teratogen Information Services regarding questions asked about paternal exposures, and briefly review what is known about the risk of paternal exposure to the 10 agents which are most frequently queried.

NF1 mutation analysis using a combined heteroduplex/SSCP approach.

Neurofibromatosis type 1 (NF1) is a common autosomal dominant disorder characterized predominantly by neurofibromas, café-au-lait spots, and Lisch nodules. The disease is caused by disruptive mutations of the large NF1 gene, with half of cases caused by new mutation. Less than 100 constitutional mutations have thus far been published, ranging from very large deletions to point mutations. We have pursued NF1 mutation analysis by heteroduplex analysis (HDA) and single-strand conformational polymorphism analysis (SSCP) of individual exons. We streamlined these techniques to eliminate the use of radioactivity, to apply both methods to the same PCR product, and to multiplex samples in gels. Applied simultaneously to a set of 67 unrelated NF1 patients, HDA and SSCP have thus far identified 26 mutations and/or variants in 45 of the 59 exons tested. Disease-causing mutations were found in 19% (13/67) of cases studied. Both techniques detected a variety of mutations including splice mutations, insertions, deletions, and point changes, with some overlap in the ability of each method to detect variants.

Bronchopulmonary-foregut malformations: a continuum of paracrine hamartomas?

The bronchopulmonary-foregut malformations (BPFM) are usually sporadic, solitary cystic hamartomas involving conducting airways, arteries, venous drainage, and lung parenchyma. Transitional, compound hamartomas exist, and only their morphology is well-known. Between 1984-1994 we encountered and studied 10 unrelated patients and a stillborn infant with BPFM (out of 24,000 families). Ten were diagnosed in utero and one at birth as having congenital cystic adenomatoid malformation of the lung (CCAML). Postnatally, two diagnoses (20%) were corrected to bronchogenic cyst (BC) and diaphragmatic hernia, respectively. Bilateral lung involvement was present in 1 patient, and in 2 there was a considerable macroscopic regression of the hamartoma. Histologic studies of the six resected CCAML confirmed the diagnosis and implied dysregulated paracrine growth with its cellular and extracellular growth factors, protooncogenes, oncogenes, cytokines, cell-adhesive molecules, and receptors of these regulatory peptides, and their complex interactions as developmental morphogens in time and space.

RET mutation screening in familial cutaneous lichen amyloidosis and in skin amyloidosis associated with multiple endocrine neoplasia.

In several families, multiple endocrine neoplasia type 2A (MEN 2A) has been found in association with cutaneous lichen amyloidosis. It has been debated, however, whether the skin amyloidosis found in MEN 2A families, localized exclusively in the interscapular area, represents the same anomaly as that found in autosomal dominant familial cutaneous lichen amyloidosis, which is more generalized. We screened two MEN 2A families with associated skin amyloidosis for germline mutations in the RET gene responsible for the MEN 2A cancer syndrome, and found the same mutation characteristic of MEN 2A in both families. We also screened probands from three pedigrees with familial cutaneous lichen amyloidosis for RET mutations. In none of the RET coding and flanking intronic sequences was a mutation detected. This most probably indicates that skin amyloidosis found in some MEN 2A families and familial cutaneous lichen amyloidosis are different conditions. Consequently, patients with apparent familial cutaneous lichen amyloidosis do not appear to be at risk for MEN 2A.

Monosomy 6q1: syndrome delineation.

We report on a girl with a de novo 6q1 interstitial deletion. To our knowledge, this is the second reported case with a deletion of 6q11-q15. We review the phenotype of monosomy 6q1. Our patient has manifestations similar to others with monosomy 6q1 including mental deficiency, growth retardation, short neck, and minor facial anomalies.

Uniparental isodisomy of chromosome 14 in two cases: an abnormal child and a normal adult.

Uniparental disomy (UPD) of a number of different chromosomes has been found in associated with abnormal phenotypes. A growing body of evidence for an imprinting effect involving chromosome 14 has been accumulating. We report on a case of paternal UPD of chromosome 14 studied in late gestation due to polyhydramnios and a ventral wall hernia. A prenatal karyotype documented a balanced Robertsonian 14:14 translocation. The baby was born prematurely with hairy forehead, retrognathia, mild puckering of the lips and finger contractures. Hypotonia has persisted since birth and at age one year, a tracheostomy for laryngomalacia and gastrostomy for feeding remain necessary. Absence of maternal VNTR polymorphisms and homozygosity of paternal polymorphisms using chromosome 14 specific probes at D14S22 and D14S13 loci indicated paternal uniparental isodisomy (pUPID). Parental chromosomes were normal. We also report on a case of maternal UPD in a normal patient with a balanced Robertsonian 14:14 translocation and a history of multiple miscarriages. Five previous reports of chromosome 14 UPD suggest that an adverse developmental effect may be more severe whenever the UPD is paternal in origin. This is the second reported patient with paternal UPD and the fifth reported with maternal UPD, and only few phenotypic similarities are apparent. Examination of these chromosome 14 UPD cases of maternal and paternal origin suggests that there are syndromic imprinting effects.

Tracheoesophageal anomalies in oculoauriculovertebral (Goldenhar) spectrum.

Tracheoesophageal fistula, with or without esophageal atresia (TEF/EA) appears to be a defect of blastogenesis, as is the oculoauriculovertebral (Goldenhar) spectrum (OAVS), with which it has occasionally been associated. We reviewed the records of all OAVS patients evaluated through the University of South Florida Regional Genetics Program between 1985 and 1993. Of 60 OAVS patients, three had TEF/EA. These results suggest that TEF/EA in association with OAVS is underreported. The occurrence of TEF/EA should prompt a thorough search for other known anomalies of OAVS.

Fragile X syndrome: discordant levels of CGG repeat mosaicism in two brothers.

Fragile X syndrome is associated with an unstable repeated CGG trinucleotide sequence in the 5' untranslated region of the FMR-1 gene. A significant number of individuals with a mild or atypical presentation are mosaics for the CGG expansion. We report a family with two brothers. The proband had severe mental retardation as well as most of the Fragile X syndrome stigmata, whereas his brother shows only mild learning difficulties. Both inherited a 80 x CGG trinucleotide premutation from the mother. They were negative for the FRAXA fragile site in over 100 metaphases examined. Flanking markers verified that both had inherited the same FMR-1 allele and Xq27-q28 flanking sequences from the mother. The methylation status of the brothers indicated active FMR-1 transcription as determined by using StB12.3/EcoRI + Eagl blots. CGG size or methylation mosaicism was not apparent from Southern blots. Polymerase chain reaction and chemiluminescent detection identified that both brothers had different degrees of mosaicism for the CGG expansion. Large expansions amounting to 70% of the total were visible in the proband, whereas less than 5% of the signal was larger than the premutation in his mildly affected brother. These findings suggest that mosaicism may be responsible for some of the variation in penetrance in this disorder.

XXY male with X-linked dominant chondrodysplasia punctata (Happle syndrome)

Happle syndrome is an X-linked dominant disorder with presumed lethality in hemizygous males; familial occurrence is rare. We describe a family with Happle syndrome affecting individuals in 3 generations. A man in this family is the first known male patient with Happle syndrome. He is severely affected; this may be due to his 47,XXY karyotype.