Family Pedigree Analysis Research Articles

Experience with cascade screening: A comprehensive family pedigree analysis of two index patients with Fabry disease.

The wide range of clinical symptoms observed in patients with Fabry disease (FD) often leads to delays in diagnosis and initiation of treatment. Delayed initiation of therapy may result in end-organ damage, such as chronic renal failure, hypertrophic cardiomyopathy, and stroke. Although some tools are available to identify undiagnosed patients, new comprehensive screening methods are needed. In this study, the outcomes of the cascade screening applied to three index cases with FD from 2 familes were investigated. In the pedigree analysis, 280 individuals were included; out of them, 131 individuals underwent genetic testing and cascade screening for FD. During the screening program, a total of 45 individuals were diagnosed, with a diagnostic ratio of 1:15. The average age at diagnosis for all individuals was 30.9 ± 17.7 years, and %25 were pediatric cases (mean age 9.5 ± 5.9 years). Thirty affected relatives were diagnosed from thetwo index cases in Family 1 and 15 individuals were diagnosedfrom one index case in Family 2. There were 13 consanguineous marriages observed among 2 pedigres, in two both spouses were affected, leading to two homozygous affected daughters in one couple. In regions where there is a high prevalence of consanguineous marriages, implementing the cascade screening approach to identify all individuals at risk can be beneficial for patients with FD, specifically women and children.

Ectopia Lentis in Three Successive Generations: A Case Series Study

Aim: To describe the clinical profiles of patients of three successive generations of a Bangladeshi family affected by familial ectopia lentis. Methods: A case series study was conducted in a tertiary eye hospital in Bangladesh from 2015 to 2019. We evaluated twentythree people of the same family of three successive generations. Among them, thirteen patients were affected by familial ectopia lentis. Several patients from all three generations underwent elaborate general examinations to rule out systemic and metabolic disorders. Results: Among thirteen patients, eleven had bilateral Ectopia lentis. Among six adult patients, three had bilateral cataracts. ICCE was done on one patient from 2nd generation (pedigree 7) in another eye hospital. The other two patients (Pedigree-2 and 9) were blind; among seven child patients, four developed cataracts. One was visually significant and underwent PPL with AVT (Pedigree-14). Visual rehabilitation was done with aphakic glass. The other three children had cataracts but not in the pupillary area - not visually significant. No systemic associations were found except one who was suspected of Marfan syndrome. Conclusions: Not only many patients in one family but also the occurrence in three generations is exceptional for Ectopia Lentis Syndrome. The autosomal recessive mode was found in other studies, but this family pedigree analysis favoured an autosomal dominant inheritance. Emphasis is needed on the importance of regular follow-up and management.

Clinical Features of Myeloid Neoplasms with Germline GATA2 Mutations–a Systematic Review of Clinical Studies Retrieved through Extensive Searching

Aims: Recent findings increasingly find individuals are being recognized as having germline predisposition to myeloid malignancies. GATA2 mutation is one of the most extensively studied germline mutations. However, until recently most of studies have focused on the mechanism of how GATA2 as one of the driver mutations causes malignancies. As regards the clinical features, such as the treatment and prognosis of myeloid neoplasms associated with germline GATA2 mutations, only small studies published, based on which they were insufficiently studied. Therefore, we did the systematic review to summarize the diagnosis, therapeutic methods and prognosis of myeloid malignant diseases associated with germline GATA2 mutations. Methods: Two reviewers independently comprehensively searched Pubmed and hand searched the professional journals and the reference lists of related and included articles from Jan 1 st, 1990 until May 1 st, 2023. They also independently screened and evaluated the retrieved records and then extracted data of included studies. Studies reported clinical materials on the diagnosis, treatment and prognosis of myeloid malignant patients with germline GATA2 mutations will be included and the clinical data will be summarized. Searching strategies were as follows: #1 germline or predispo* or somat* or famil* or germ line or congenit* or altera* or non-tumor; #2 gene* or genom* or sequenc* or muta* or SNP or abnormal* or translocat* or chromosom* or frameshift* or exom* or GATA; #3 “acute myeloid leukemia” “Leukemia, Myeloid, Acute” “Myelodysplastic Syndromes” “refractory anemia” “myeloid or myeloblast*” or AML or MDS; #4 #1 and #2 and #3 Results: 2457 records were retrieved and 23 studies with 396 patients were included. Screening process was shown in Figure 1. Studies included were all small sample sized. The diagnosis age was from three to 78 years old, most of the median ages of included studies were less than 30 years indicated carriers would have symptoms in young age, on the other hand, there were also patients who began having symptoms in old age (the oldest 78 years) or remained asymptomatic carriers without getting sick in the whole life. There was no sex difference. Emberger syndrome which caused lymphedema and MonoMAC and/or DCML (dendritic cell, monocyte, B-lymphocyte and NK-lymphocyte) deficiency syndromes that caused cytopenia and infections were generally appeared earlier before myeloid malignancies. Myelodysplastic syndrome (MDS), acute myeloid leukemia (AML) and chronic myelomonocytic leukemia (CMML) are common malignant diseases for patients with germline GATA2 mutations predisposition. The morbidity was not able to be calculated based on the data available. MDS was the most common myeloid neoplasm compared with AML and CMML which were always transformed from MDS. Other hematologic malignancies were rare. The disease transformation was shown from refractory cytopenia to malignant clonal hematopoiesis that caused MDS, and then transformed into leukemia. In total, 311/396 (78.5%) patients developed malignant myeloid diseases. Nine studies had done the family pedigree analysis and there were 162 family members who had the germline GATA2 mutations predisposition, in which there were 32 asymptomatic carriers (19.7%). 128 patients were reported to receive allogeneic hematopoietic stem cell transplantation (allo-HSCT), 81 (63.3%) were alive and 44 (34.4%) died of relapse or transplantation related complications. Three patients' outcome was unknown. In study Michael A. Spinner et al, survival rate was 54% by 4 years after allo-HSCT (21 patients included). Nearly all patients (15/18) with myeloid malignancies who did not receive transplantation had died. The most common cytogenetic abnormalities were monosomy 7 and trisomy 8, and other abnormalities were also common. Conclusions: Most of germline GATA2 mutation carriers will have symptoms in young age and many of them will progress into malignant myeloid diseases. Allo-HSCT was effective to treat symptomatic patients, especially for patients with malignant hematologic diseases, and furthermore that is the only curative treatment. Asymptomatic carriers are not rare and for them regular tests are essential. More clinical studies on germline GATA2 mutations for myeloid neoplasms are needed to clarify the clinical features in this setting and improve its treatment and prognosis.

Pedigree Analysis of Families and Patients Affected by Retinitis Pigmentosa.

Family pedigrees allow for a more thorough understanding of human genetic disorders. They are used to help establish patterns of inheritance and to identify individuals at risk of disease. Pedigree analysis can be helpful in identifying genetic disorders that demonstrate mechanisms such autosomal dominant or recessive inheritance, X-linked inheritance, and anticipation.

Prevalence of Phenylthiocarbamide (PTC) Taste Sensitivity and Colour Blindness in Tengger Tribe Population, Ranupani Village, Senduro, Lumajang

The taste of sensitivity of phenylthiocarbamide (PTC), is autosomal dominant trait inherited while the colour blindness is a sex linked genetic trait on the X chromosome. The purpose of this study was to determine the distribution of taster and non taster phenotypes, prevalence of color blindness, frequency of taster and non taster alleles, and frequency of color blind alleles, as well as pedigree analysis in non taster and color blind families. The research was conducted on the Tengger tribe, in Ranupani village, Senduro, Lumajang. Determination of the sample is carryout randomly. Detection of the ability to taste PTC was respondents to taste the PTC solution from the lowest concentration of 0.32mg/L (P13) to the highest concentration of 1300 mg/L (P1). Color blindness detection by the Ishihara method. The results of the study showed that the distribution of the taster was 98.1% while the non-taster was 1.9%. The allele frequency of the dominant taster (T) was 0.86 and the recessive allele non taster (t) is 0.14. The prevalence of color blindness in the population of the Tengger tribe was 0.63% and the allele frequency for color blindness was 0.013. The pedigree analysis of non taster family showed that non taster individuals were born from taster couple (Tt) or from couple of non taster (tt) with tasters (Tt) heterozigot. While the pattern of inheritance of color blindness was criss-cross inheritance pattern, which is passed from mother to son.

A novel RHD allele, with c.491A > T (p.Asp164Val) mutation, identified via family pedigree analysis

A Chinese Han man was confirmed to carry an RHD variation by serological tests, and exons 1 through 10 of the RHD gene were analyzed by sequence-specific primer-polymerase chain reaction. To clarify the nature of this mutation, Sanger sequencing was used and a c.491A > T mutation was identified in exon 4. The proband inherited this mutation from his father, as determined from a family pedigree.

Genetics of Dentofacial and Orthodontic Abnormalities.

The development of craniofacial complex and dental structures is a complex and delicate process guided by specific genetic mechanisms. Genetic and environmental factors can influence the execution of these mechanisms and result in abnormalities. An insight into the mechanisms and genes involved in the development of orofacial and dental structures has gradually gained by pedigree analysis of families and twin studies as well as experimental studies on vertebrate models. The development of novel treatment techniques depends on in-depth knowledge of the various molecular or cellular processes and genes involved in the development of the orofacial complex. This review article focuses on the role of genes in the development of nonsyndromic orofacial, dentofacial variations, malocclusions, excluding cleft lip palate, and the advancements in the field of molecular genetics and its application to obtain better treatment outcomes.

Phenotypic heterogeneity of impacted third molar tooth: family case study

Tooth impaction is a pathological condition where a tooth fails to attain its normal functional position. The present study aims to highlight the phenotypic heterogeneity of impacted third molars in a Caucasian family, to investigate the characteristics of the dental phenotype, to evidence the diversity of dental phenotype, and to identify the inheritance mode of the condition. Detailed anamnesis, clinical examination, complementary tests (panoramic radiographs), family study and pedigree analysis. Phenotypic characteristics of impacted third molar tooth in our family case report was: Severe horizontal impaction of the mandibular right third molar, Angular impaction of the maxillary right third molar and angular impaction of the maxillary left third molar, Angular impaction of the mandibular left third molar and partial eruption of the maxillary right third molar, Horizontal impaction of the mandibular left third molar and Angular impaction of the mandibular left third molar. The inheritance mode of the impacted third molar tooth in the family case report was: from mother to both daughters’ transmission, from mother to both sons’ transmission, and from mother to daughter transmission. Family study and pedigree analysis are very important for illustrate the genetic basis of impacted teeth.

Familial Dilated Cardiomyopathy – Enhancing Detection Using Systematic Screening

Background: Dilated cardiomyopathy (DCM) is the leading indication for heart transplantation in New Zealand (NZ). The familial subtype (FDCM) is aggressive, presents early, and is implicated in up to 50% of idiopathic DCM (IDCM). Diagnosis requires an affected individual having ≥2 affected close relatives. Adequate family pedigree analysis is diagnostically essential, and screening relatives is imperative as pre-symptomatic therapy improves outcomes. We utilised a validated family history survey to screen our NZ heart transplant population for FDCM more systematically. Methods: Medical records of living heart transplant patients with IDCM or FDCM diagnoses (77/339 patients) were reviewed. Patients were provided our survey via post/email and at clinic visits. We evaluated our 12 question clinical survey's efficacy in obtaining a complete three-generation family history and compared that to information documented in the medical records. Results: Fifty-one (66%) surveys were returned. Complete family history was obtained in 47/51 (92.2%), compared with 10/51 (19.6%) specifically documented in medical records. Responders identified 16 relatives who were also referred for heart transplantation, or who died ≤50 years with cardiomyopathy. The tool diagnosed FDCM in 25/51 (49.0%, with a further 3 possible FDCM), already yielding 6 additional patients not previously diagnosed. The mean age at first presentation of FDCM was 37 years (23 were male, 2 female), compared with 43 years in the IDCM group. Conclusion: Utilising a formal family screening tool improves pedigree analysis ensuring more effective detection of FDCM, which is prevalent in the NZ transplant cohort. Formalised systematic screening has great potential to improve outcomes.

Genealogical characteristics of children and adolescents with cholelithiasis and their families

One of the common pathologies of the hepatobiliary tract is cholelithiasis. The prevalence of this disease among children and adolescents is of particular concern.The purpose of the study is to identify the family aggregation of the hepatobiliary pathology and other multifactorial diseases in the pedigrees of children and adolescents with cholelithiasis.Materials and methods. Genealogical analysis was performed in 105 families with sick children aged from 2 to 17 years who were examined and treated for hepatobiliary tract disorders in gastroenterological and somatic departments. The comparison group comprised 75 family pedigrees of peers, inhabitants of the Kharkiv region, who were not diagnosed with cholelithiasis and other serious non-communicable diseases.Results. Gastroduodenal pathology ranked first among the families of sick children in the morbidity prevalence patterns in terms of gastrointestinal tract pathology (14.29 % vs. 6.19 % in relatives of healthy children, P < 0.001), followed by cholelithiasis (13.19 % vs. 0.44 % in relatives of healthy children, P < 0.001), and other diseases of the hepatobiliary system ranked third – (7,21 % vs. 5,59 % in relatives of healthy children, P > 0.05). In our studies, the calculation of cholelithiasis formation depending on the gender identity of sick children relatives also confirmed that in the female subjects the risk of cholelithiasis was 6.7 times increased compared with the male population (OR = 6.69; CI = 3.71–12.06; p < 0.05). Diseases such as cholelithiasis and other diseases of the hepatobiliary system, gastroduodenal pathology and cardiovascular disorders prevailed among the first-degree relatives of children suffering from cholelithiasis in comparison with these diseases diagnosis in relatives of healthy children.Conclusions. Based on the family pedigree analysis of patients and healthy children, an inherited predisposition to cholelithiasis was determined in 63.81 % of sick children families, and it was 15.9 times higher than the incidence of this disease in healthy children families, thus made it possible to consider this indicator as a prognostic sign for cholelithiasis development. Familial aggregation of cholelithiasis, other diseases of the hepatobiliary system and gastroduodenal pathology in the first-degree relatives; cholelithiasis and gastroduodenal pathology in the second-degree relatives; cholelithiasis in the third-degree relatives was revealed compared with the frequency of these diseases in healthy children families. The maternal inheritance of cholelithiasis was found more frequently than paternal and both maternal and paternal. The odds ratio (OR) value in the presence of cholelithiasis in the sick children families was 24.7 times increased; 2,6 times – in the presence of gastroduodenal pathology; 1.5 times – in the presence of other diseases of the hepatobiliary system compared with the frequency of these diseases in healthy children families; and 6.7 times for females.

Association of sporadic and familial Barrett's esophagus with breast cancer.

Barrett's esophagus (BE) is the only known precursor to esophageal adenocarcinoma (EAC). Based on striking aggregation of breast cancer and BE/EAC within families as well as shared risk factors and molecular mechanisms of carcinogenesis, we hypothesized that BE may be associated with breast cancer. Pedigree analysis of families identified prospectively at multiple academic centers as part of the Familial Barrett's Esophagus Consortium (FBEC) was reviewed and families with aggregation of BE/EAC and breast cancer are reported. Additionally, using a matched case-control study design, we compared newly diagnosed BE cases in Caucasian females with breast cancer (cases) to Caucasian females without breast cancer (controls) who had undergone upper endoscopy (EGD). Two familial pedigrees, meeting a stringent inclusion criterion, manifested familial aggregation of BE/EAC and breast cancer in an autosomal dominant inheritance pattern with incomplete penetrance. From January 2008 to October 2016, 2812 breast cancer patient charts were identified, of which 213 were Caucasian females who underwent EGD. Six of 213 (2.82%) patients with breast cancer had pathology-confirmed BE, compared to 1 of 241 (0.41%) controls (P-value<0.05). Selected families with BE/EAC show segregation of breast cancer. A breast cancer diagnosis is marginally associated with BE. We postulate a common susceptibility between BE/EAC and breast cancer.

Prenatal Detection of Cryptic Genomic Rearrangement: Role of Detailed Family History, Pedigree Analysis and Advanced Genomic Technologies

Prenatal Detection of Cryptic Genomic Rearrangement: Role of Detailed Family History, Pedigree Analysis and Advanced Genomic Technologies

Double segment chromosomal imbalance due to inherited chromosomal translocation: Detection by cytogenetic microarray

Balanced translocations are common with the incidence of 1 in 500. Two cousins with intellectual disability with family history of holoprosencephaly. Microarray showed gain on chromosome 7 and loss on chromosome 11 and vice versa in the other cousin. We highlight the importance of detailed family history, pedigree analysis, and utility of microarray.

Association between the p.V37I variant of GJB2 and hearing loss: a pedigree and meta-analysis.

Pathogenic variants in the gap junction protein beta-2 (GJB2) gene are the most common cause of hearing loss. Of these, the p.V37I variant of GJB2 has a high allele frequency (up to 10%) in East Asians. Characterization of the phenotypic spectrum associated with p.V37I, as well as the role of this variant in the onset of hearing loss could have a remarkable effect on future diagnostic strategies. Here, we performed a pedigree analysis of unrelated families exhibiting various hearing phenotypes, and then conducted a meta-analysis to comprehensively assess the association between the p.V37I and the risk of hearing loss. Pedigree analyses showed that both homozygous p.V37I variants, as well as compound heterozygous p.V37I with other GJB2 pathogenic variants, contributed to various phenotypes of hearing loss. Meanwhile, meta-analysis demonstrated that, compared with those in the wild type group, both p.V37I homozygotes and compound heterozygous p.V37I variants were at significantly higher risk of developing hearing loss (odds ratios = 7.14 and 3.63; 95% confidence intervals = 3.01-16.95 and 1.38–9.54, respectively). Conversely, heterozygous p.V37I variants alone did not increase the risk of hearing loss. Given the high allele carriage rate of p.V37I (up to 10%) within the general population, our work not only provides information that might influence future genetic screening policies, but also offers insight into clinical risk evaluation and genetic counseling regarding hearing loss.

A 45-SNP genetic risk score is increased in early-onset coronary artery disease but independent of familial disease clustering

Background and aimsCommon genetic risk variants may contribute to the heritability of early-onset coronary artery disease (CAD). We aimed to investigate the association of a genetic risk score (GRS) with age upon CAD-onset and to test the association between the GRS, familial clustering, and CAD severity in early-onset CAD. Methods134 early-onset CAD patients (<40 years), 446 late-onset CAD patients (male >55 years/female >65 years), and 89 healthy controls were genotyped for 45 CAD-associated SNPs and a GRS was created. In early-onset CAD patients, family pedigrees with information on 1585 1st and 2nd degree relatives were used to calculate a stratified log-rank family score (SLFS) as a measure of familial clustering. ResultsEarly-onset patients had a higher mean GRS than late-onset CAD patients (p = 0.02) and healthy controls (p < 0.0001). In the adjusted model, a GRS increase of one SD was associated with 1.2 years (95% CI 0.1–2.2) earlier onset. The GRS was not associated with the SLFS in the regression model (p = 0.41) and did not differ between SLFS tertiles (p = 0.98). The SLFS predicted the number of affected coronary vessels (OR [95% CI] per SD increase in SLFS: 2.0 [1.4–3.0]), whereas the association between the GRS and CAD severity was not statistically significant (OR [95% CI] per SD increase in GRS: 1.3 [0.9–1.9]). ConclusionsThe GRS was increased in early-onset CAD patients, but not associated with the SLFS, suggesting that these common genetic variants are of minor importance in familial clustering of early-onset CAD. Furthermore, family pedigree analysis may predict CAD severity more precisely than common variants.

Discovery of candidate genes for nonsyndromic cleft lip palate through genome-wide linkage analysis of large extended families in the Malay population.

BackgroundNonsyndromic orofacial clefts are one of the most common birth defects worldwide. It occurs as a result of genetic or environmental factors. This study investigates the genetic contribution to nonsyndromic cleft lip and/or palate through the analysis of family pedigrees. Candidate genes associated with the condition were identified from large extended families from the Malay population.ResultsA significant nonparametric linkage (NPL) score was detected in family 100. Other suggestive NPL and logarithm of the odds (LOD) scores were attained from families 50, 58, 99 and 100 under autosomal recessive mode. Heterogeneity LOD (HLOD) score ≥ 1 was determined for all families, confirming genetic heterogeneity of the population and indicating that a proportion of families might be linked to each other. Several candidate genes in linkage intervals were determined; LPHN2 at 1p31, SATB2 at 2q33.1-q35, PVRL3 at 3q13.3, COL21A1 at 6p12.1, FOXP2 at 7q22.3-q33, FOXG1 and HECTD1 at 14q12 and TOX3 at 16q12.1.ConclusionsWe have identified several novel and known candidate genes for nonsyndromic cleft lip and/or palate through genome-wide linkage analysis. Further analysis of the involvement of these genes in the condition will shed light on the disease mechanism. Comprehensive genetic testing of the candidate genes is warranted.

Familial dilated cardiomyopathy diagnosis is commonly overlooked at the time of transplant listing

The prevalence and clinical characteristics of familial dilated cardiomyopathy (FDCM) among patients with end stage heart failure (ESHF) has yet to be elucidated. We sought to determine the prevalence of FDCM in ESHF in the United Network for Organ Sharing (UNOS) registry and compare this with center specific data from a large tertiary teaching hospital. Patients with a banked UNOS diagnosis of dilated cardiomyopathy (DCM) whose care originated at our center then underwent detailed pedigree analysis in order to determine the true prevalence of FDCM. A total of 16,091 patients with DCM from all centers were identified in the UNOS registry of whom 492 carried the diagnosis of FDCM (3.1%). Patients with the diagnosis of FDCM tended to be younger (42 versus 49 years old in idiopathic dilated cardiomyopathy (IDCM), p=0.001), were less likely to have diabetes (7.8% versus 16.5% in IDCM, p<0.0001), had slightly lower creatinine (1.2 versus 1.4 in IDCM, p=0.0001) and were more likely to have a panel reactive antibody level ≥ 20% (62.1% versus 44.7% in IDCM, p<0.0001). Consecutive living adult patients with ESHF were identified from the UNOS registry that had been treated at the Yale Center for Advanced Heart Failure (YCAHF). After excluding all diagnoses that did not include any form of non-ischemic DCM, 73 patients met the inclusion criteria. Center-specific UNOS data showed pre-pedigree analysis diagnosis of FDCM in 4.12% of patients (3 out of 73), consistent with that found in the UNOS database for all centers. However, after detailed family history and pedigree analysis, 19 (26%) of 73 patients were found to have FDCM, while the remaining 54 were found to have IDCM. Echocardiographic findings including mitral regurgitation, mitral valve annulus and left ventricular end diastolic dimension were not significantly different between groups when adjusting for multiple testing. The diagnosis of FDCM was missed in the majority of patients with end stage heart failure enrolled in the UNOS database, as sampled from a large, tertiary care teaching hospital in the United States. Echocardiographic findings are unlikely to aid in the differentiation between DCM and FDCM. Detailed pedigree analysis can successfully identify undiagnosed FDCM and should be encouraged prior to transplant listing as it has important implications for early detection and treatment of disease in family members.

Variant in the RFWD3 gene associated with PATN1, a modifier of leopard complex spotting.

Leopard complex spotting (LP), the result of an incompletely dominant mutation in TRPM1, produces a collection of unique depigmentation patterns in the horse. Although the LP mutation allows for expression of the various patterns, other loci are responsible for modification of the extent of white. Pedigree analysis of families segregating for high levels of patterning indicated a single dominant gene, named Pattern-1 (PATN1), as a major modifier of LP. Linkage analysis in two half-sibling families segregating for PATN1 identified a 15-Mb region on ECA3p that warranted further investigation. Whole transcriptome sequencing of skin samples from horses with and without the PATN1 allele was performed to identify genic SNPs for fine mapping. Two Sequenom assays were utilized to genotype 192 individuals from five LP-carrying breeds. The initial panel highlighted a 1.6-Mb region without a clear candidate gene. In the second round of fine mapping, SNP ECA3:23 658 447T>G in the 3'-UTR of RING finger and WD repeat domain 3 (RFWD3) reached a significance level of P = 1.063 × 10(-39). Sequencing of RFWD3 did not identify any coding polymorphisms specific to PATN1 horses. Genotyping of the RFWD3 3'-UTR SNP in 54 additional LP animals and 327 horses from nine breeds not segregating for LP further supported the association (P = 4.17 × 10(-115)). This variant is a strong candidate for PATN1 and may be particularly useful for LP breeders to select for high levels of white patterning.

Single-molecule PCR analysis of an unstable microsatellite for detecting mutations in sperm of mice exposed to chemical mutagens

Single-molecule PCR (SM-PCR) analysis of long and repetitive DNA sequences, known as expanded simple tandem repeats (ESTRs), has been the most efficient method for studying germline mutation induction in endogenous sequences to date. However, the long length of these sequences makes mutation detection imprecise and laborious, and they have been characterized only in mice. Here, we explore the use of unstable microsatellite sequences that can be typed with high precision by capillary electrophoresis as alternative loci for detecting germline mutations. We screened 24 microsatellite loci across inbred mouse strains and identified Mm2.2.1 as the most polymorphic microsatellite locus. We then optimized SM-PCR of Mm2.2.1 to detect mutations in sperm. SM-PCR analysis of sperm from untreated B6C3F1 and Muta™Mouse samples revealed mutation frequencies that are consistent with rates derived from family pedigree analysis (∼5×10−3). To determine whether this locus can be used to detect chemically induced germline mutations, Muta™Mouse males were exposed by oral gavage to a single dose of 100mg/kg of N-ethyl-N-nitrosourea (ENU) or to 100mg/kg of benzo(a)pyrene (BaP) for 28 days alongside vehicle treated controls. Sperm were collected 10 weeks post-ENU exposure to sample sperm exposed as spermatogonial stem cells and 6 weeks post-BaP exposure to sample sperm that were dividing spermatogonia when the exposure was terminated. Both treatments resulted in a significant (approximately 2-fold) increase in mutation frequency in sperm compared to the control animals. The work establishes the utility of this microsatellite for studying mutation induction in the germ cells of mice. Because microsatellites are found in virtually every species, this approach holds promise for other organisms, including humans.

Detection of mutations in symptomatic patients with hypertrophic cardiomyopathy in Taiwan

BackgroundHypertrophic cardiomyopathy (HCM) is a common genetic cardiac disorder associated with sudden death, heart failure, and stroke. The aim of the present study was to evaluate the prevalence and types of mutations in symptomatic patients with HCM in Taiwan. MethodsThirty-eight HCM index patients (mean age 60±16 years) underwent systematic mutation screening of eight sarcomeric genes: β-myosin heavy chain (MYH7), myosin-binding protein C (MYBPC3), troponin T (TNNT2), troponin I (TNNI3), myosin ventricular regulatory light chain 2 (MYL2), myosin ventricular essential light chain 1 (MYL3), α-tropomyosin (TPM1), and cardiac α-actin (ACTC), using direct DNA sequencing. In silico programs predicted damaging amino acids. In the positive families, genotype–phenotype correlation studies were done. ResultsOverall, 13 mutations were identified in 13 index patients (34.2%). The three most frequently mutated genes were MYH7, MYBPC3, and TNNT2. One patient carried double mutations. Five mutations (MYH7 R147S; MYBPC3 R597Q; MYBPC3 W1007R; TNNI3 E124Q; MYL3 R63C) were novel; all were missense mutations. Analysis using in silico tools showed near consensus to classify these five novel mutations as pathological. Family pedigree analysis showed the presence of cosegregation in at least two affected members in each proband family, but incomplete penetrance in young family members with a positive genotype. ConclusionsWe identified 13 HCM pedigrees, including 5 carrying novel mutations and 1 with a double mutation. The three most commonly mutated genes were MYH7, MYBPC3, and TNNT2. These results, together with genetic counseling, could lead to earlier diagnosis and better management of family members at risk of HCM.