Detection of LAMA2 c.715C>G:p.R239G mutation in a newborn with raised creatine kinase: A case report

Abstract

BACKGROUND

We report a rare case of primary clinical presentation featuring elevated creatine kinase (CK) levels in a neonate, which is associated with the LAMA2 gene. In this case, a heterozygous mutation in exon5 of the LAMA2 gene, c.715C>G (resulting in a change of nucleotide number 715 in the coding region from cytosine to guanine), induced an amino acid alteration p.R239G (No. 239) in the patient, representing a missense mutation. This observation may be elucidated by the neonatal creatine monitoring mechanism, a phenomenon not previously reported.

CASE SUMMARY

We analysed the case of a neonate presenting solely with elevated CK levels who was eventually discharged after supportive treatment. The chief complaint was identification of increased CK levels for 15 d and higher CK values for 1 d. Admission occurred at 18 d of age, and despite prolonged treatment with creatine and vitamin C, the elevated CK levels showed limited improvement. Whole exome sequencing revealed the presence of a c.715C>G mutation in LAMA2 in the newborn, correlating with a clinical phenotype. However, the available information offers insufficient evidence for clinical pathogenicity.

CONCLUSION

Mutations in LAMA2 are associated with the clinical phenotype of increased neonatal CK levels, for which no specific treatment exists. Whole genome sequencing facilitates early diagnosis.

Key Words: Creatine kinase; LAMA2; Gene mutation; Neonate; Case report

Core Tip: We analyzed the case of a neonate who appeared with only elevated creatine kinase (CK) and eventually was discharged after supportive treatment. The age of admission was 18 d, and the increased CK did not improve significantly after prolonged treatment with creatine and vitamin C. Whole exome sequencing identified the mutation of c.715C>G on LAMA2 in the newborn, which is associated with clinical phenotype.

INTRODUCTION

Creatine kinase (CK), a biomarker of muscle damage, fluctuates within a certain reference range, 40-320 IU/L and 25-200 IU/L for men and women, respectively. Increased CK may be related to muscle damage[1] and it may be asymptomatic[2]. A few similar reports have been found worldwide, and previous reports have shown that increased CK levels in newborns are related to genetic variations. In this article, we describe the clinical manifestations, diagnosis, and treatment of a newborn with increased CK values associated with LAMA2 gene mutation. The newborn was diagnosed in the term ward of the Children's Hospital of Soochow University. This study aimed to improve our understanding of this disease and advocated that neonatal clinicians should be aware of the serious potential problem of abnormally elevated CK in newborns shortly after birth.

CASE PRESENTATION

Chief complaints

Identification of increased CK levels for 15 d and higher CK values for 1 d.

History of present illness

The neonate was admitted to Changshu First People's Hospital for 8 d post-birth due to "perinatal infection". During this period, CK value were found to be elevated, peaking at 1348 U/L, with no specific treatment administered. After discharge, CK values continued to increase for 8 d, reaching a maximum of 2111 U/L.

History of past illness

The neonate, born at Changshu First People's Hospital on June 14, 2023, via eutocia at a gestational age 39 wk and mother being G2P2, had a birth weight 3700 g and recorded Apgar scores of 10 at both 1 min and 5 min post-birth. Amniotic fluid was clear, with a normal quantity, and no history of rescue suffocation was noted.

However, after birth, the neonate was hospitalised at Changshu First People's Hospital for 9 d due to perinatal infection, clavicle fracture caused by birth injury, neonatal hyperbilirubinemia, atrial septal defect, and neonatal ischaemic hypoxic myocardial damage.

Personal and family history

The mother was diagnosed with hypothyroidism and gestational hypertension at 11 and 26 wk gestation, respectively. Group B strep was a potential concern at 36 wk gestation, while the parents of the newborn had no significant medical history, were physically healthy, and were not close relatives.

Physical examination

Upon examination, the newborn displayed a body temperature of 36.5 °C, a pulse rate of 170 beats/min, a respiratory rate of 40 breaths/min, and an oxygen pulse of 99% under hood oxygen. Physical measurements included a body weight of 4.04 kg, a length of 52 cm, a head circumference of 35 cm, and a chest circumference of 34 cm. The newborn exhibited a full term appearance with a ruddy complexion, a flat anterior fontanel, measuring about 1.5 cm × 1.5 cm, and soft neck. The newborn experienced no shortness of breath, no obvious inspiratory trifossa sign, the lungs indicated rough breathing sounds without rales. Additionally, a grade 2/6 systolic murmur was audible at the left margin of the sternum and between the 2^nd and 3^rd ribs. The abdomen was soft, the extremities were warm, and the primitive reflexes were elicited, with normal muscular tone.

Laboratory examinations

Peripheral blood examination revealed a CK value 2155.10 U/L. Myocardial enzyme levels indicated CK-MB at 7.70 ng/mL, troponin-T 42.81 ng/mL, myoglobin < 21 ng/mL. White blood cell count 9.77 × 10⁹/L, red blood cell count 4.08 × 10¹²/L, hemoglobin 138 g/L, platelet distribution width 12.90%, and blood gas analysis showed Na⁺ 134 mmol/L, Ca²⁺ 1.15 mmol/L, Cl^- 10² mmol/L, base excess 1.9 mmol/L, lactic acid 1.60 mmol/L, blood pH 7.496, oxyhemoglobin saturation 99.10%, oxygen partial pressure 119.0 mmHg, carbon dioxide partial pressure 31.70 mmHg, aspartic transaminase 42.30 U/L, alanine aminotransferase 44.10 U/L, total bilirubin 131.30 μmol/L, direct bilirubin 12.60 μmol/L, indirect bilirubin 118.70 μmol/L. Triiodothyronine, thyroxine, thyroid-stimulating hormone, free triiodothyronine, and free thyroxine levels showed no obvious abnormalities, and inflammatory markers showed no significant increases. Newborn screening results were unremarkable.

Imaging examinations

Chest and abdominal imaging demonstrated an increase and blurring of the lung texture alongside changes indicative of aright clavicle fracture. Echocardiography suggested atrial septal defect, categorised as a secundum type with a size of 3.1 mm.

CK-related gene test

The patient (chr6:129465121) showed a heterozygous mutation of c.715C>G in the gene LAMA2; while the father (chr6:129465121) had a heterozygous mutation of c.715C>G:p.R239G; No mutations were detected in the mother (chr6:129465121) (Figure 1). Large fragment variations in LAMA2 were absent (Figure 2).

Figure 1 Creatine kinase-related gene test. A: The patient, chr6:129465121 had a heterozygous mutation of c.715C>G:p.R239G in the gene LAMA2; B: The father, chr6:129465121 had a heterozygous mutation of c.715C>G:p.R239G; C: The mother, chr6:129465121 had no mutations.

Figure 2 Creatine kinase-related gene test. No large fragment variation of the patient was found in LAMA2 gene.

FINAL DIAGNOSIS

Elevated CK levels; perinatal infection; fracture of the collarbone due to birth injury; atrial septal defect; neonatal pneumonia.

TREATMENT

After the newborn’s hospitalisation, CK levels continuously increased, stabilising at approximately 2000 U/L. Upon active treatment with vitamin C and creatine phosphate sodium, the CK values decreased from 2155.1 U/L to 1803.1 U/L in 15 d, and remained significantly higher than the normal values. Therefore, an investigation into CK-related genes was undertaken, resulting in the diagnosis of elevated CK levels in the neonate. Throughout the hospitalisation period, apart from the increased CK levels, no notable clinical manifestations were observed. The liver function index and bilirubin levels did not exhibit significant increases. The patient did not experience breathing difficulties, digestive system abnormalities, cardiac dysfunction, or disruption in normal milk intake. Additionally, all inflammatory markers remained within the normal range. Genetic problems were also considered in this study. Gene examination was performed and supportive treatments were administered. However, CK values showed no discernible decline. Eight days after admission, the child developed a lower respiratory tract infection caused by respiratory syncytial virus (RSV). Following comprehensive therapy, including creatine phosphate sodium and vitamin C, the neonate was discharged after 19 d of hospitalisation. Healthcare-associated infections related to RSV occurred during the disease course, with administration of antiviral and anti-inflammatory treatments, expectorant drugs, and probiotics to alleviate symptoms of cough. Vitamin C and creatine phosphate sodium were administered for 11 d during hospitalisation but were discontinued upon discharge. Subsequently, CK levels gradually subsided. After a 180-d follow-up period, the child’s exhibited normal growth and development, with neurologic evaluations revealing no abnormalities in motor development, limb weakness stiffness, or sitting ability to. The patient weighed 8 kg, and CK levels remained at approximately 400 U/L.

OUTCOME AND FOLLOW-UP

Gene mutation analysis revealed a heterozygous mutation in the exon5 region of the LAMA2 gene: c.715C>G (with nucleotide 715 in the coding region changing from cytosine to guanine), resulting in the amino acid change p.R239G (No. 239), characterised as a missense mutation[3]. This change led to replacement of amino acid arginine with glycine. Interpretation of multiplex ligation-dependent probe amplification indicated absence of large fragment variations in the LAMA2 gene, with the population exhibiting a low frequency of morbidity associated with this gene. Upon verification within the family, the father showed a heterozygous variation at the same site, while the mother of the neonate showed no variation, suggesting a suspected mutation. Had the father exhibited similar symptoms, it might have implicated diseases theoretically caused by the mutation site, or conversely, the mutation site might have been very small. However, no significant fragment variations were observed at the exon level, and gross motor development was normal during the 180-d follow-up.

DISCUSSION

Increased CK levels in neonates can be attributed to various factors, including both physiological and pathological factors. Physiologically, elevated CK levels may arise from compression injury of the skeletal muscle and transient hypoxia during vaginal birth[4,5]. Pathologically, elevations in CK levels can stem from cardiogenic diseases, endocrine and genetic metabolic diseases, inflammatory myopathies, autoimmune diseases, and drug interactions between metabolised pharmaceuticals[6,7]. Additionally, surgeries, other injuries, seizures, or direct drug toxicity from medications can induce muscle damage affecting CK values[6,7]. Understanding the multifaceted etiology of elevated CK is complicated. CK elevations can occur at birth due to compression damage to skeletal muscles and temporary hypoxia. Data indicate that in normal newborns, CK values increased rapidly after birth, stabilising within normal ranges within a week[8]. However, in our case, despite the neonate being delivered full-term normally, a peripheral blood examination indicated a significant increase in CK levels one day after birth, persisting for 16 d. Therefore, physiological factors are excluded. Despite receiving creatine and vitamin C supplements for 11 d during hospitalisation, the neonate’s CK values remained unchanged, indicating that supplementation did not reduce elevation. Echocardiography revealed an atrial septal defect, 3.1 mm in size, and it was a secundum type. However, no significant increase in pulmonary hypertension or myocardial enzymes such as CK-MB and cardiac troponin T was observed. Moreover, clinical manifestations of circulation failure or heart failure were not obvious. Thus, cardiogenic diseases were excluded. The child's mother had a history of hypothyroidism triiodothyronine. Nevertheless, thyroxine, thyroid-stimulating hormone, free triiodothyronine, and free thyroxine of the child were all normal, and the thyroid gland exhibited normal functioning with no obvious manifestations of thyroid dysfunction; thus, thyroid problem was excluded. Therefore, other potential factors contributing to elevated CK levels were considered.

Monitoring increased CK levels in newborns can facilitate early detection of CMD before symptom onset[5]. Notably, a nonsense mutation, c.4048C>T (p.Arg1350*) in exon 27 may contribute to severe CMD[9]. A small percentage of individuals with elevated CK levels receive a diagnosis of hereditary myopathy[10,11]. While the mutational site lacks sufficient evidence for clinical pathogenicity, it remains linked to the phenotype observed in this case. According to the guidelines[12-15], the mutation of c.715C>G in the LAMA2 gene is classified as a site of unknown significance. This variation is absent in various databases, including the human thousand genome (1000G), Chellonese genome database, human exon database (ExAC), and human genome mutation frequency database (gnomAD). After 180 d of clinical follow-up, the newborn’s condition gradually improved. Comprehensive phenotypic information and genetic testing of family members can aid in further evaluating the correlation between variation sites and this case. An unexplained and repeated rise in CK warrants genetic testing. In our patient, genetic testing revealed a heterozygous mutation in the CK-related gene LAMA2, inherited from the father. In this case, despite elevated CK levels, the newborn in this case displayed no unusual facies, suggesting that the c.715C>G mutation may be related to the features of increased CK. This child had no special clinical manifestations other than exceptionally high CK levels, in which case Early treatment, genetic testing, and infection prevention are crucial in such cases. These results expand our understanding of genetic diseases associated with CK and highlights the significance of linkage analysis in gene discovery studies.

CONCLUSION

Increased CK caused by a heterozygous mutation of the LAMA2 gene has no specific treatment and can be self-limiting. Neonatal diseases can be diagnosed early through increasingly advanced genetic diagnostics. Monitoring and discovery of resymptomatic patients during the neonatal period will contribute to clinical research and measurable treatment procedures to observe therapeutic effects. In view of this case, neonatologists should observe an unexplained increase in CK and implement pathological analysis and whole-exome sequencing to make an early conclusive diagnosis and treatment.