Autosomal Dominant Pedigrees Research Articles

Imprinting Status of 11p15 Genes in Beckwith–Wiedemann Syndrome Patients with CDKN1C Mutations

Beckwith–Wiedemann syndrome (BWS) is an imprinting disorder characterized by somatic overgrowth, congenital malformations, and predisposition to childhood tumors. Aberrant expression of multiple imprinted genes, including H19, IGF2, KCNQ1OT1, and CDKN1C, has been observed in BWS patients. It has been estimated that mutations in CDKN1C occur in 12–17% of BWS patients. We have screened 10 autosomal dominant pedigrees and 65 sporadic BWS cases by PCR/heteroduplex analysis and DNA sequencing and have identified four mutations, two of which were associated with biallelic IGF2 expression and normal H19 and KCNQ1OT1 imprinting. One patient demonstrated phenotypic expression of paternally transmitted mutation in this maternally expressed gene, a second proband is the child of one of a pair of monozygotic twin females who carry the mutation de novo, and a third patient exhibited unusual skeletal changes more commonly found in other overgrowth syndromes. When considered with other studies published to date, this work reveals the frequency of CDKN1C mutations in BWS to be only 4.9%. This is the first report of an analysis of the imprinting status of genes in the 11p15 region where CDKN1C mutations were associated with loss of IGF2 imprinting and maintenance of H19 and KCNQ1OT1 imprinting.

Alport Syndrome: From Genes to Bedside

Alport syndrome (AS) is an inherited disorder characterized by the familial occurrence in successive generations of progressive nephritis with hematuria and of neural hearing loss. 1 Male patients usually have severe renal disease with progressive renal failure occurring before the fourth decade, whereas most females tend to have a normal life span. The first symptoms, usually consisting of microscopic or macroscopic hematuria, occur in early life, especially in males. Hematuria may in rare cases be observed at birth. Other presenting symptoms of AS include proteinuria, edema, hypertension, deafness and renal failure. Hearing defects may not be present in all affected members of a family and are more frequent in male patients. However, the real incidence of hearing loss is difficult to evaluate in the absence of systematic audiological studies. Associated changes in other organs, such as eyes or smooth muscles, and cell types, such as platelets and granulocytes, are known to occur in some patients with AS. The disease follows an X-linked trait in approximately 80% of the cases, whereas autosomal recessive, autosomal dominant and uninformative pedigrees account for the remainder. 2

Exclusion of Identified LGMD1 Loci from Four Dominant Limb-Girdle Muscular Dystrophy Families

The limb-girdle muscular dystrophies are a clinically and genetically heterogeneous group of disorders. Recent linkage analyses and positional cloning studies have identified numerous loci responsible for the recessive and dominant forms, underscoring the inherent heterogeneity. In this report, we investigate four large autosomal dominant limb-girdle pedigrees and exclude these pedigrees from linkage to these loci. In addition, there is no evidence for linkage to any of the seven recessive LGMD loci.

Gene locus FPD1 of the dystonic Mount-Reback type of autosomal-dominant paroxysmal choreoathetosis.

Genes for paroxysmal choreoathetosis have been localized to chromosomes 1p and 2q. We have reinvestigated one of the classic large autosomal-dominant pedigrees of the dystonic Mount-Reback type of paroxysmal choreoathetosis 20 years after its first assessment. These patients prefer diazepam for both prevention and treatment of attacks and did not develop addiction on an intermittent regime. Migraine occurred in a third of the patients. Genetic data localized the underlying mutation to the FPD1 locus (familial paroxysmal dyskinesia type 1) on chromosome 2q and support locus homogeneity for the Mount-Reback syndrome. The data also refine the FPD1 candidate region to 3.6 cM between the markers D2S164 and D2S2359, which may facilitate the investigation of the role of the candidate ion channel gene SLC2C.

SMN gene analysis of the spinal form of Charcot-Marie-Tooth disease.

The spinal form of Charcot-Marie-Tooth disease (spinal CMT) is a rare genetic disorder of the peripheral nervous system, the genetic basis of which remains unknown. To test the hypothesis that...

A Gene for Autosomal Dominant Congenital Nystagmus Localizes to 6p12

Congenital nystagmus is an idiopathic disorder characterized by bilateral ocular oscillations usually manifest during infancy. Vision is typically decreased due to slippage of images across the fovea. As such, visual acuity correlates with nystagmus intensity, which is the amplitude and frequency of eye movements at a given position of gaze. X-linked, autosomal dominant, and autosomal recessive pedigrees have been described, but no mapping studies have been published. We recently described a large pedigree with autosomal dominant congenital nystagmus. A genome-wide search resulted in six markers on 6p linked by two-point analysis at θ = 0 (D6S459, D6S452, D6S465, FTHP1, D6S257, D6S430). Haplotype analysis localizes the gene for autosomal dominant congenital motor nystagmus to an 18-cM region between D6S271 and D6S455.

Clinical variability of facioscapulohumeral muscular dystrophy in russia

One hundred forty-two patients (66 men and 76 women) from 20 autosomal-dominant pedigrees and 3 families including 5 "sporadic" cases were examined. A great similarity of clinical manifestations among those affected was noted. Clinical variability of phenotypes reflecting various phases of the disease and different expressions of the mutant gene were always within the limits of the identical final phenotype of the disease, namely the facio-scapulo-humero-peroneal-femoro (posterior group of the muscles)-gluteal (gluteus maximus). Thus, the clinically and genetically homogeneous group of patients with autosomal-dominant descending with a "jump" form of facioscapulohumeral dystrophy (FSHD), called facioscapuloperoneal dystrophy (FSPD), was examined. Among the observed cases we did not come across any having the autosomal-dominant gradually descending form of FSHD, called facioscapulolimb dystrophy (FSLD), in which the pelvic and proximal lower limb muscles get weak earlier than in the peroneal group (anterior tibial) muscles. We could not reveal the "pure" facioscapulohumeral phenotype of muscle weakness in 142 examined patients. A "pure" FSHD does not exist as a nosological entity. It represents only the syndrome which characterizes the initial phase of FSLD, but not of the FSPD. It is quite probable that FSPD and FSLD which may be differentiated clinically are two different diseases connected with the mutation of allelic or even different genes. Linkage studies in FSPD and FSLD mapping genes would confirm this data.